Approved Document B (fire safety) volume 2: Buildings other than dwellings, 2019 edition incorporating 2020, 2022 and 2025 amendments collated with 2026 and 2029 amendments

Source page 1

HM Government

The Building Regulations 2010

Fire safety

APPROVED DOCUMENT

Volume 2: Buildings other than dwellings

Requirement B1: Means of warning and escape

Requirement B2: Internal fire spread (linings)

Requirement B3: Internal fire spread (structure)

Requirement B4: External fire spread

Requirement B5: Access and facilities for the fire service

Regulations: 6(3), 7(2) and 38

Also includes: 2026 amendments 2029 amendments

2019 edition incorporating 2020, 2022 and 2025 amendments and forthcoming 2026 and 2029 changes – for use in England

Source page 2

The changes focus on the following fire safety provisions in blocks of flats (Volume 1):

a.Sprinklers:

•A reduction in the trigger height from 30m to 11m.

b.Wayfinding signage for the fire service:

•A new recommendation for floor identification and flat indication signage within blocks of flats with storeys over 11m.

In addition a typographical error is corrected in both volumes. Purpose group number 2 is now included in reference to ‘residential’ buildings in the guidance on boundaries.

The changes are set out in the May 2020 AD B amendments.

Main changes made by the 2022 amendments

The changes focus on the following fire safety provisions:

a.Ban of combustible materials in and on the external walls of buildings:

Consequential amendments following the laying of the Building (Amendment) (England) Regulations 2022.

Updated provisions in Section 12 for residential buildings (purpose groups 1 and 2) with a storey 11m or more in height.

b.Clarifications and corrections:

Clarification of further diagrams, further text clarifications and corrections.

The changes are set out in the June 2022 AD B amendment booklet and the November 2022 correction notice.

Source page 3

The changes focus on the following fire safety provisions:

a.Regulation 38 and fire safety information.

b.Removal of national classes for reaction to fire and roofs.

c.Introduction of new provisions for sprinklers in care homes.

The changes are set out in the March 2025 AD B amendments.

Changes made by the 2026 and 2029 amendments

This document also includes the 2026 amendments and 2029 amendments to Approved Document B Volume 2, as laid out in the respective amendment booklets.

Source page 4

Please note that ‘building notice’, ‘initial notice’ and ‘building control approval application with full plans’ have the meanings given in the Building Regulations 2010. For the purpose of these transitional arrangements, building work is to be regarded as ‘sufficiently progressed’:

a.where the building work consists of the construction of a building, when the pouring of concrete for the permanent placement of the trench, pad or raft foundations has started, or the permanent placement of piling has started; or

b.where the building work consists of work to an existing building, when that work has started; or

c.where the building work consists of a material change of use of a building, when work to effect that change of use has stated.

Source page 5

What is an approved document?

Approved documents are approved by the Secretary of State and give practical guidance on common building situations about how to meet the requirements of the Building Regulations 2010 for England. Different approved documents give guidance on each of the technical parts of the regulations. These are all listed in the back of the approved documents. In addition to guidance, some approved documents include provisions that must be followed exactly, as required by regulations or where methods of test or calculation are approved by the Secretary of State.

Each approved document covers the requirements of the Building Regulations 2010 relating to a different aspect of building work. Building work must also comply with all other applicable requirements of the Building Regulations 2010 and all other applicable legislation.

How is construction regulated in England?

Most building work being carried out in England must comply with the Building Regulations 2010. The Building Regulations are made under powers in the Building Act 1984.

Building Regulations protect the health and safety of people in and around buildings, they also provide for energy and water conservation and access to and use of buildings.

The Manual to the Building Regulations (references to this in the introduction are taken from the first edition) gives an overview of the building regulatory system in England. You can access the most recent version of the manual at: www.gov.uk/guidance/building-regulations-and-approved-documents-index.

How do you comply with the Building Regulations?

Building work must meet all relevant requirements of the Building Regulations. To comply with the Building Regulations, it is necessary both to follow the correct procedures and meet technical performance requirements.

The approved documents set out what, in ordinary circumstances, may be accepted as one way to comply with the Building Regulations. Note, however, that:

•Complying with the guidance in the approved documents does not guarantee that building work complies with the requirements of the regulations – the approved documents cannot cover all circumstances. Those responsible for building work must consider whether following the guidance in the approved documents is likely to meet the requirements in the particular circumstances of their case.

•There may be other ways to comply with the requirements than those described in an approved document. If those responsible for meeting the requirements prefer to meet a requirement in some other way than described in an approved document, they should seek to agree this with the relevant building control body at an early stage.

Source page 6

Those responsible for building work include agents, designers, builders, installers and the building owner. For further information, see Chapter 7 in Volume 1 and paragraphs A26, B2 and F2 in Volume 2 of the Manual to the Building Regulations.

The Building Regulations can be contravened by not following the correct procedures or not meeting the technical performance requirements. If the building owner or those responsible for the works contravene the Building Regulations, the local authority may prosecute them in the magistrates’ court. For further information on enforcement and sanctions in the existing system, see Chapter B in Volume 2 of the Manual to the Building Regulations.

What do the Building Regulations cover?

‘Building work’ is a legal term for work covered by the Building Regulations. Where a building is not exempt, the Building Regulations apply to all types of building work as defined in regulation 3 of the Building Regulations. For further information, what constitutes building work is covered in Chapter A, Volume 2 of the Manual to the Building Regulations.

The Building Regulations contain sections dealing with definitions, procedures and the expected technical performance of building work. For example, the Building Regulations:

a.define what types of building, plumbing and heating work are classed as building work in regulation 3 (for further information see paragraphs A14 to A16 in Volume 2 of the Manual to the Building Regulations).

b.specify types of building that are exempt from the Building Regulations (for further information see Table A1 and paragraph A11 in Volume 2 of the Manual to the Building Regulations).

c.set out the notification procedures to follow when undertaking building work (for further information see Figure 2.1 in Volume 1 of the Manual to the Building Regulations).

d.set out the technical requirements (see Table 7.1 in Volume 1 of the Manual to the Building Regulations) with which the individual aspects of building design and construction must comply in the interests of the health and safety of building users, of energy efficiency (for further information see paragraphs A12(d)–(f), A14(f)–(h), A22, A23, B2(c) and F24 in Volume 2 of the Manual to the Building Regulations), and of access to and use of buildings.

e.set out the standards for building materials and workmanship in carrying out building work (for further information see Chapter 7 in Volume 1, and paragraphs F8 to F11 in Volume 2 of the Manual to the Building Regulations).

When must a building control body be notified?

It is often necessary to notify a building control body of planned building work. To help ensure that work complies with the Building Regulations, those responsible for building work may need to use one of the two types of building control body listed below:

a.a local authority building control body

b.a private sector building control service.

Source page 7

If building work consists only of installing certain types of services or fittings (e.g. fuel-burning appliances or replacement windows) and the building owner employs an installer that is registered with a relevant competent person scheme designated in the regulations, a building control body does not need to be notified.

How to use this approved document

Each approved document contains:

•general guidance on the performance expected of materials and building work in order to comply with each of the requirements of the Building Regulations, and

•practical examples and solutions on how to achieve compliance for some of the more common building situations.

They may not provide appropriate guidance if the case is unusual in terms of its design, setting, use, scale or technology. Non-standard conditions may include any of the following:

•difficult ground conditions

•buildings with unusual occupancies or high levels of complexity

•very large or very tall buildings

•large timber buildings

•some buildings that incorporate modern construction methods.

Anyone using the approved documents should have sufficient knowledge and skills to understand the guidance and correctly apply it to the building work. This is important because simply following the guidance does not guarantee that your building work will comply with the legal requirements of the Building Regulations. Each approved document contains legal requirements (which you must follow) and guidance (which you may or may not choose to follow). The text in a box with a green background at the beginning of each section of an approved document is taken from the Building Regulations. This text sets out the legal requirements.

The explanation which follows the legal requirements is guidance (see Diagram i below). The guidance then explains one or more ways to demonstrate how building work can be shown to comply with the legal requirements in common circumstances. The terms in green lettering in an approved document are key terms, listed and explained in the appendix to that approved document. Guidance in the approved documents addresses most, but not all, situations that building owners will face. Situations may arise that are not covered. You or your advisers will need to carefully consider whether following the guidance will mean that the requirements of the Building Regulations will be met.

Source page 8

Requirement B2: Internal fire spread (linings)

This section deals with the following requirement from Part B of Schedule 1 to the Building Regulations 2010.

Intention

In the Secretary of State’s view, requirement B2 is met by achieving a restricted spread of flame over internal linings. The building fabric should make a limited contribution to fire growth, including a low rate of heat release.

It is particularly important in circulation spaces, where linings may offer the main means by which fire spreads and where rapid spread is most likely to prevent occupants from escaping.

Requirement B2 does not include guidance on the following.

a.Generation of smoke and fumes.

b.The upper surfaces of floors and stairs.

c.Furniture and fittings.

Key

➊ The law: extract from the Building Regulations 2010.

➋ Statutory guidance.

For further information about the use of technical guidance, see Chapter 7 in Volume 1 and Chapter F in Volume 2 of the Manual to the Building Regulations.

Where to get further help

If you are unsure whether you have the knowledge and skills to apply the guidance correctly, or if you do not understand the technical guidance or other information in this approved document or the additional detailed technical references to which it directs you, you should seek further help. Some sources of help are listed below.

a.Your building control body may be able to help in many cases.

b.If you are registered with a competent person scheme, the scheme operator should be in a position to help.

c.Suitably qualified and experienced construction professionals should also be engaged where necessary.

Source page 9

Introduction

•What is an approved document? — i

•How is construction regulated in England? — i

•How do you comply with the Building Regulations? — i

•What do the Building Regulations cover? — ii

•When must a building control body be notified? — ii

•How to use this approved document — iii

•Where to get further help — iv

Section 0: Approved Document B: Fire safety – buildings other than dwellings

•Summary — 1

•Arrangement of sections — 1

•Management of premises — 2

•Property protection — 2

•Inclusive design — 2

•Alternative approaches — 3

•Purpose groups — 5

•Mixed use buildings — 7

Requirement B1: Means of warning and escape

•Intention — 8

Section 1: Fire detection and alarm systems

•General provisions — 9

•Fire detection and alarm systems — 9

•Design and installation of systems — 11

Section 2: Design for horizontal escape

•Introduction — 12

•Escape route design — 12

•Residential care homes — 25

Section 3: Design for vertical escape

•Introduction — 28

•Number of escape stairs — 28

•Provision of refuges — 29

•Width of escape stairs — 30

•Design and protection of escape stairs — 36

Source page 10

Construction 42

Travel distance and number of escape routes 42

Escape stairs in small premises 46

Section 5: General provisions

Introduction 47

Protection of escape routes 47

Doors on escape routes 47

General provisions 49

Lifts 51

Refuse chutes and storage 52

Shop store rooms 53

Requirement B2: Internal fire spread (linings)

Intention 54

Section 6: Wall and ceiling linings

Classification of linings 55

Thermoplastic materials 57

Requirement B3: Internal fire spread (structure)

Intention 62

Section 7: Loadbearing elements of structure

Fire resistance standard 63

Raised storage areas 64

Section 8: Compartmentation/sprinklers

Provision of compartmentation 65

Sprinklers 69

Construction of compartment walls and compartment floors 69

Openings in compartmentation 72

Protected shafts 72

Section 9: Cavities

Provision of cavity barriers 77

Pathways around fire-separating elements 77

Extensive cavities 79

Construction and fixings for cavity barriers 80

Section 10: Protection of openings and fire-stopping

Introduction 82

Openings for pipes 82

Mechanical ventilation and air-conditioning systems 83

Source page 11

Flues, etc. 87

Fire-stopping 87

Section 11: Special provisions for car parks

Requirement B4: External fire spread

Intention 93

Section 12: Resisting fire spread over external walls

Introduction 94

Combustibility of external walls 94

Balconies 96

Metal composite materials 97

Regulation 7(2) and requirement B4 97

Section 13: Resisting fire spread from one building to another

Introduction 99

Boundaries 99

Unprotected areas and fire resistance 102

Methods for calculating acceptable unprotected area 105

Section 14: Resisting fire spread over roof coverings

Introduction 107

Separation distances 107

Requirement B5: Access and facilities for the fire service

Intention 110

Section 15: Vehicle access

Buildings not fitted with fire mains 111

Buildings fitted with fire mains 113

Design of access routes and hardstandings 113

Section 16: Fire mains and hydrants

Introduction 116

Provision of fire mains 116

Design and construction of fire mains 116

Provision of private hydrants 117

Section 17: Access to buildings for firefighting personnel

Introduction 118

Provision of firefighting shafts 119

Location of firefighting shafts 120

Design and construction of firefighting shafts 122

Rolling shutters in compartment walls 122

Source page 12

Provision of smoke outlets 123

Construction of outlet ducts or shafts 125

Basement car parks 125

Regulation 38: Fire safety information

Intention 127

Section 19: Fire safety information

Appendix A: Key terms

Appendix B: Performance of materials, products and structures

Introduction 138

Reaction to fire 139

Thermoplastic materials 140

Fire resistance 141

Application of the fire resistance standards in Table B2 149

Appendix C: Fire doorsets

Appendix D: Methods of measurement

Occupant number 175

Travel distance 177

Width 177

Building dimensions 178

Free area of smoke ventilators 181

Appendix E: Sprinklers

Sprinkler systems 182

Design of sprinkler systems 183

Water supplies and pumps 183

Appendix F: Standards referred to

European Standards 184

British Standards 185

Appendix G: Documents referred to

Legislation 187

Other documents 187

Index 189

Source page 13

Summary

0.1This approved document has been published in two volumes. Volume 1 deals solely with dwellings, including blocks of flats, while Volume 2 deals with all other types of building covered by the Building Regulations.

Arrangement of sections

0.2Requirements B1–B5 of Schedule 1 to the Building Regulations are dealt with separately in one or more sections. Each requirement is shown at the start of the relevant sections.

0.3The provisions in this document have the following aims:

Requirement B1: When there is a fire, ensure both:

a.satisfactory means of sounding an alarm

b.satisfactory means of escape for people.

Requirement B2: Inhibit the spread of fire over internal linings of buildings.

Requirement B3: The building must be built such that all of the following are achieved in the event of a fire:

a.the premature collapse of the building is avoided

b.sufficient fire separation is provided within buildings and between adjoining buildings

c.automatic fire suppression is provided where necessary

d.the unseen spread of fire and smoke in cavities is restricted.

Requirement B4: Restrict both:

a.the potential for fire to spread over external walls and roofs (including compliance with regulations 6(4) and 7(2))

b.the spread of fire from one building to another.

Requirement B5: Ensure both:

a.satisfactory access for the fire service and its appliances

b.facilities in buildings to help firefighters save the lives of people in and around buildings.

Regulation 38: Provide fire safety information to building owners.

0.4Guidance is given on each aspect separately, though many are closely interlinked. The document should be considered as a whole. The relationship between different requirements and their interdependency should be recognised. Particular attention should be given to the situation where one part of the guidance is not fully followed as this could have a negative effect on other provisions.

Source page 14

0.5Guidance on matters that refer to more than one section of this document can be found in the following appendices.

Appendix A: Key terms

Appendix B: Performance of materials, products and structures

Appendix C: Fire doorsets

Appendix D: Methods of measurement

Appendix E: Sprinklers

Appendix F: Standards referred to

Appendix G: Documents referred to

Management of premises

0.6The Building Regulations do not impose any requirements on the management of a building, but do assume that it will be properly managed. This includes, for example, keeping protected escape routes virtually ‘fire sterile’.

Appropriate fire safety design considers the way in which a building will be managed. Any reliance on an unrealistic or unsustainable management regime cannot be considered to have met the requirements of the regulations.

Once the building is in use, the management regime should be maintained and a suitable risk assessment undertaken for any variation in that regime. Failure to take proper management responsibility may result in the prosecution of an employer, building owner or occupier under legislation such as the Regulatory Reform (Fire Safety) Order 2005.

Property protection

0.7The Building Regulations are intended to ensure a reasonable standard of life safety in a fire. The protection of property, including the building itself, often requires additional measures. Insurers usually set higher standards before accepting the insurance risk.

Many insurers use the RISCAuthority Design Guide for the Fire Protection of Buildings by the Fire Protection Association (FPA) as a basis for providing guidance to the building designer on what they require.

Further information on the protection of property can be obtained from the FPA website: www.thefpa.co.uk.

Inclusive design

0.8The fire safety aspects of the Building Regulations aim to achieve reasonable standards of health and safety for people in and around buildings.

People, regardless of ability, age or gender, should be able to access buildings and use their facilities. The fire safety measures incorporated into a building should take account of the needs of everyone who may access the building, both as visitors and as people who live or work in it. It is not appropriate, except in exceptional circumstances, to assume that certain groups of people will be excluded from a building because of its use.

Source page 15

The provisions in this approved document are considered to be of a reasonable standard for most buildings. However, some people’s specific needs might not be addressed. In some situations, additional measures may be needed to accommodate these needs. This should be done on a case-by-case basis.

Alternative approaches

0.9The fire safety requirements of the Building Regulations will probably be satisfied by following the relevant guidance in this approved document. However, approved documents provide guidance for some common building situations and there may be alternative methods of complying with the Building Regulations’ requirements.

If alternative methods are adopted, the overall level of safety should not be lower than the approved document provides. It is the responsibility of those undertaking the work to demonstrate compliance.

If other standards or guidance documents are adopted, the relevant fire safety recommendations in those publications should be followed in their entirety. However, in some circumstances it may be necessary to use one publication to supplement another. Care must be taken when using supplementary guidance to ensure that an integrated approach is used in any one building.

Guidance documents intended specifically for assessing fire safety in existing buildings often include less onerous provisions than those for new buildings and are therefore unlikely to be appropriate for building work that is controlled by the Building Regulations.

Buildings for industrial and commercial activities that present a special fire hazard, e.g. those that sell fuels, may require additional fire precautions to those in this approved document.

Health care premises

0.10Health care premises and the patients who use them are diverse. Patients using the premises require different types of care to suit their specific needs. The choice of fire safety strategy depends on both of the following.

a.How a building is designed, furnished, staffed and managed.

b.The needs of the patients.

The Department of Health (DoH) guidance documents on fire precautions in health care buildings, Firecode, take account of the particular characteristics of these buildings and should be followed.

Firecode contains managerial and other fire safety provisions that are outside the scope of the Building Regulations.

Unsupervised group homes

0.11An unsupervised group home for not more than six mental health service users should be regarded as having a purpose group of either of the following.

a.An existing house of one or two storeys for which the means of escape are provided in accordance with DoH HTM 88 should be regarded as a purpose group 1(c) building.

b.A new building may be more appropriately regarded as being in purpose group 2(b).

Shopping complexes

0.12Although the guidance in this document may be readily applied to individual shops, shopping complexes present different escape problems. The design of units within a shopping complex should be compatible with the fire strategy for the complex as a whole. A suitable approach is given in Annex E of BS 9999.

Source page 16

0.13Assembly buildings where a large number of people are present require additional considerations for means of escape; for example, fixed seating may limit the ability of people to escape.

Guidance on fixed seating and other aspects of means of escape in assembly buildings is given in Annex D of BS 9999.

For buildings to which the Safety of Sports Grounds Act 1975 applies, the Sports Grounds Safety Authority’s Guide to Safety at Sports Grounds should also be followed.

Schools

0.14The design of fire safety in schools is covered by Building Bulletin 100, which should be used. Building Bulletin 100 contains fire safety provisions that are outside the scope of the Building Regulations.

Prisons provided under section 33 of the Prisons Act 1952

0.15Prisons are exempted from the functional requirements of Parts B1 to B5 of the Building Regulations under section 33 of the Prisons Act 1952. It is usual that prisons should comply with the fire safety requirements of the Building Regulations, except where the requirements are incompatible with safe custody, good order or security.

HM Prison and Probation Service (HMPPS) provides guidance documents on fire precautions in prisons, which take account of the public safety need to secure doors and exits while maintaining life safety objectives.

The HMPPS Custodial Premises Fire Safety Design Guide (FSDG) is the design standard for fire safety in prisons, providing structured guidance for those involved in the planning, designing or approval of new or altered buildings.

Further guidance documents on fire safety in prisons are provided by HMPPS. These documents may also be used for other places of lawful detention.

Buildings containing one or more atria

0.16A building with an atrium that passes through compartment floors may need special fire safety measures. Guidance is given in Annexes B and C of BS 9999.

Buildings of special architectural or historic interest

0.17Where Part B applies to existing buildings, particularly buildings of special architectural or historic interest for which the guidance in this document might prove too restrictive, some variation of the provisions in this document may be appropriate. In such cases, it is appropriate to assess the hazard and risk in the particular case and consider a range of fire safety features in that context.

Fire safety engineering

0.18Fire safety engineering might provide an alternative approach to fire safety. Fire safety engineering may be the only practical way to achieve a satisfactory standard of fire safety in some complex buildings and in buildings that contain different uses.

Fire safety engineering may also be suitable for solving a specific problem with a design that otherwise follows the provisions in this document.

0.19BS 7974 and supporting published documents (PDs) provide a framework for and guidance on the application of fire safety engineering principles to the design of buildings.

Source page 17

0.20Building uses are classified within different purpose groups, which represent different levels of hazard (see Table 0.1). A purpose group can apply to a whole building or to a compartment within the building, and should relate to the main use of the building or compartment.

0.21Where a building or compartment has more than one use, it is appropriate to assign each different use to its own purpose group in the following situations.

a.If the ancillary use is a flat.

b.If both of the following apply.

i.The building or compartment has an area of more than 280m².

ii.The ancillary use relates to an area that is more than one-fifth of the total floor area of the building or compartment.

c.In ‘shop and commercial’ (purpose group 4) buildings or compartments, if the ancillary use is storage and both of the following apply.

i.The building or compartment has an area of more than 280m².

ii.The storage area comprises more than one-third of the total floor area of the building or compartment.

0.22Where there are multiple main uses that are not ancillary to one another (for example, shops with independent offices above), each use should be assigned to a purpose group in its own right. Where there is doubt as to which purpose group is appropriate, the more onerous guidance should be applied.

Source page 18

Source page 19

Mixed use buildings

0.23This approved document includes reference to selected guidance for dwellings. For the design of mixed use buildings which include dwellings, Approved Document B Volume 1 should be consulted in addition to the guidance contained in this approved document.

0.24Where a complex mix of uses exists, the effect that one use may have on another in terms of risk should be considered. It could be necessary to use guidance from both volumes, apply other guidance (such as from HTM 05-02 or Building Bulletin 100), and/or apply special measures to reduce the risk.

Source page 20

These sections deal with the following requirement from Part B of Schedule 1 to the Building Regulations 2010.

Intention

In the Secretary of State’s view, requirement B1 is met by achieving all of the following.

a.There are sufficient means for giving early warning of fire to people in the building.

b.All people can escape to a place of safety without external assistance.

c.Escape routes are suitably located, sufficient in number and of adequate capacity.

d.Where necessary, escape routes are sufficiently protected from the effects of fire and smoke.

e.Escape routes are adequately lit and exits are suitably signed.

f.There are appropriate provisions to limit the ingress of smoke to the escape routes, or to restrict the spread of fire and remove smoke.

The extent to which any of these measures are necessary is dependent on the use of the building, its size and its height.

Building work and material changes of use subject to requirement B1 include both new and existing buildings.

Source page 21

General provisions

1.1All buildings should have arrangements for detecting fire and raising the alarm. In most buildings, fires are detected by people, either by sight or smell, and therefore often nothing more is needed.

1.2In some small buildings/premises, the means of raising the alarm may be simple (for example, a shouted warning). In assessing appropriate solutions, warnings need to be heard and understood throughout the premises.

Fire detection and alarm systems

1.3Other than for some small buildings/premises, an electrically operated fire alarm system should be provided. In some situations, the alarm should be operated by a fire detection system. The detailed specification should be compatible with the fire strategy for the building.

1.4In ‘residential (institutional)’ and ‘residential (other)’ occupancies (purpose groups 2(a) and 2(b)), automatic fire detection and alarms should be provided.

1.5Automatic fire detection and alarm systems should be provided in non-residential occupancies where a fire could break out in an unoccupied part of the premises (e.g. a storage area or a part of the building that is not visited on a regular basis) and prejudice the means of escape from occupied part(s) of the premises.

1.6Automatic fire detection will also be necessary where fire protection systems, such as pressure differential systems or door releases, need to operate automatically.

1.7Every building design should be assessed individually. General guidance on the category of fire detection system that may need to be provided within a building can be found in Table A1 of BS 5839-1.

1.8Where an electrically operated fire detection and alarm system is provided, it should comply with BS 5839-1.

1.9BS 5839-1 specifies three categories of system.

a.Category L – for the protection of life.

b.Category M – manual fire detection and alarm systems.

c.Category P – for property protection.

Source page 22

Category L systems are divided into the following.

L1 – systems installed throughout the protected building.

L2 – systems installed only in defined parts of the protected building (a category L2 system will normally include the coverage required of a category L3 system).

L3 – systems designed to warn of fire at an early enough stage to enable all occupants, other than possibly those in the room where the fire started, to escape safely before the escape routes become impassable because of fire, smoke or toxic gases.

L4 – systems installed within those parts of the escape routes that comprise circulation areas and circulation spaces, such as corridors and stairs.

L5 – systems in which the protected area(s) and/or the location of detectors are designed to satisfy a specific fire safety objective (other than that of a category L1, L2, L3 or L4 system).

Type P systems are divided into the following.

P1 – systems installed throughout the protected building.

P2 – systems installed only in defined parts of the protected building.

1.10Electrical alarm system call points should comply with either of the following.

a.BS 5839-2.

b.BS EN 54-11 Type A (direct operation).

Call points should be installed in accordance with BS 5839-1.

Type B (indirect operation) call points of BS EN 54-11 should only be used with the approval of the building control body.

1.11A voice alarm system complying with BS 5839-8, and giving a fire warning different from other signals in general use, may be considered if either of the following applies.

a.People might not respond quickly to a fire warning.

b.People are unfamiliar with the fire warning arrangements.

1.12In premises where lots of members of the public are present, an initial general alarm may be undesirable. Any fire alarm system that first alerts staff should comply with BS 5839-1.

1.13Where the escape strategy is based on simultaneous evacuation, actuation of the fire alarm system should give warning from all fire alarm sounders. Where phased evacuation is planned, a staged alarm system is appropriate. See paragraph 3.21.

1.14BS 9999 provides guidance for fire detection and alarm systems in buildings containing atria.

Warnings for people with impaired hearing

1.15Clause 18 of BS 5839-1 gives detailed guidance on the design and selection of fire alarm warnings for people with impaired hearing. In buildings or parts of a building where people may be in relative isolation, a visual and audible fire alarm may be the most appropriate solution. In buildings where the population is managed, a vibrating personal paging system may be more appropriate.

Source page 23

1.16Fire detection and alarm systems must be properly designed, installed and maintained. A design, installation and commissioning certificate should be provided for fire detection and alarm systems. Third party certification schemes for fire protection products and related services are an effective means of providing assurances of quality, reliability and safety.

Interface between fire detection and alarm systems and other systems

1.17Fire detection and alarm systems sometimes trigger other systems. The interface between systems must be reliable. Particular care should be taken if the interface is facilitated via another system. Where any part of BS 7273 applies to the triggering of other systems, the recommendations of that part of BS 7273 should be followed.

Student accommodation

1.18In student residences that are designed and occupied as a block of flats, separate automatic detection should be provided in each self-contained flat where all of the following apply.

a.A group of up to six students shares the flat.

b.Each flat has its own entrance door.

c.The compartmentation principles for flats in Section 7 of Approved Document B Volume 1 have been followed.

Where a total evacuation strategy is adopted, the alarm system should follow the guidance elsewhere in this section.

Source page 24

Introduction

2.1Means of escape should be provided from any point on a storey to the storey exit, for all types of building. The general principle is that any person confronted by a fire within a building can turn away from it and escape safely.

2.2For small shop, office, industrial, storage and other similar premises, the guidance on small premises (see section 4) may be followed instead of the provisions in this section, if they meet both of the following conditions.

a.No storey has an area more than 280m².

b.There is a maximum of two storeys plus a basement storey.

Escape route design

Number of escape routes and exits

2.3The number of escape routes and exits that should be provided depends on both of the following.

a.The number of occupants in the room, tier or storey.

b.The limits on travel distance to the nearest exit given in Table 2.1 (which apply only to the nearest exit; other exits may be further away).

2.4In multi-storey buildings, if more than one stair is needed for vertical escape, every part of each storey should have access to more than one stair. An area may be in a dead end provided the alternative stair is accessible.

2.5In mixed use buildings, separate means of escape should be provided from any storeys or parts of storeys used for the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose groups 1, 2 and 5).

Source page 25

2.6A single escape route is acceptable for either of the following.

a.Parts of a floor from which a storey exit can be reached within the limit for travel distance in one direction shown in Table 2.1 (see also paragraph 2.8), provided the following apply.

i.For places of assembly and bars, no one room in this situation has more than 60 people.

ii.For ‘residential (institutional)’ buildings (purpose group 2(a)), no one room in this situation has more than 30 people. Occupant number calculations are described in Appendix D.

b.A storey with no more than 60 people, where the limits on travel distance in one direction only are satisfied (see Table 2.1).

2.7In many cases, the beginning of a route will not have an alternative escape route (for example, a single exit from a room into a corridor where escape is possible in two directions). This is acceptable if both of the following apply.

a.The travel distance to the nearest storey exit is within the limits for routes where escape is possible in more than one direction (Table 2.1).

b.The travel distance for the ‘one direction only’ section of the route does not exceed the limit for travel distance where there is no alternative escape route (Table 2.1).

Diagram 2.1 shows how to measure travel distances from a dead end in an open storey layout.

Source page 26

•Any compressed, liquefied or dissolved gas.

•Any substance that becomes dangerous by interaction with either air or water.

•Any liquid substance with a flash point below 65°C, including whisky or other alcoholic liquor.

•Any corrosive substance.

•Any oxidising agent.

•Any substance liable to spontaneous combustion.

•Any substance that changes or decomposes readily, giving out heat when doing so.

•Any solid substance with a flash point less than 120°C.

•Any substance that is likely to spread fire by flowing from one part of a building to another.

Source page 27

2.8Measures to restrict access to the building (or parts of it) should not adversely affect fire safety provisions. It may be reasonable to close some escape routes outside normal business hours, but measures should remain to safely evacuate people left inside the building (see paragraph 5.6).

Number of occupants and exits

2.9The building design should be based on the number of occupants. If the number is not known, use the appropriate floor space factors (Appendix D).

Table 2.2 gives the minimum number of escape routes and exits from a room or storey for different numbers of occupants. This number is likely to be increased by the need to observe travel distances and other practical considerations.

The width of escape routes and exits is given in paragraph 2.18.

Alternative escape routes

2.10Alternative escape route should satisfy one of the following criteria.

a.They are in directions 45 degrees or more apart (Diagram 2.2).

b.They are in directions less than 45 degrees apart, but separated from each other by fire resisting construction.

Inner rooms

2.11An inner room is at risk if a fire starts in the access room (Diagram 2.3). Such an arrangement should only be accepted if all of the following conditions are satisfied.

Source page 28

a.The occupant number of the inner room does not exceed:

i.30 people for ‘residential (institutional)’ buildings (purpose group 2(a))

ii.60 people for other purpose groups.

b.The inner room is not a bedroom.

c.The inner room is entered directly from the access room (but not via a corridor).

d.The escape route from the inner room does not pass through more than one access room.

e.The travel distance from any point in the inner room to the exits from the access room does not exceed the distances in Table 2.1.

f.The access room meets both of the following conditions.

i.It is not a place of special fire hazard.

ii.It is in the control of the same occupier.

g.One of the following arrangements is made.

i.The enclosures (walls or partitions) of the inner room stop a minimum of 500mm below the ceiling.

ii.The door or walls of the inner room contain a vision panel (minimum 0.1m²), so people can see if a fire starts in the access room.

iii.The access room is fitted with an automatic fire detection and alarm system to warn occupants of the inner room if a fire starts in the access room.

Planning of exits in a central core

2.12Where a central core has more than one exit, storey exits should be remote from one another and no two exits should be approached from the same lift hall, common lobby or undivided corridor (Diagram 2.4).

Source page 29

2.13Escape routes should not be within 4.5m of openings between floors, such as for an escalator, unless either of the following applies.

a.The direction of travel is away from the opening.

b.An alternative escape route does not pass within 4.5m of the open connection (Diagram 2.5).

Source page 30

2.14Where a storey has more than one escape stair, it should be planned so that it is not necessary to pass through one stair to reach another. However, it would be acceptable to pass through one stair’s protected lobby to reach another stair.

Separation of circulation routes from protected stairways

2.15Where they serve protected stairways that are part of primary circulation routes, self-closing fire doors should be fitted with an automatic release mechanism, to avoid them being rendered ineffective by misuse. Otherwise, the stair (and any associated exit passageway) should not form part of the primary circulation route between different parts of the building at the same level.

Storeys divided into different uses

2.16If a storey contains areas for consuming food and/or drink, and where that is not the main use of the building, then both of the following apply.

a.A minimum of two escape routes should be provided from each area, except from inner rooms that meet the conditions in paragraph 2.11.

b.Those escape routes should lead directly to a storey exit without entering a kitchen or similar area of high fire hazard.

Storeys divided into different occupancies

2.17Where a storey is divided into areas of occupancy under separate ownership or tenancy, then both of the following apply.

a.The means of escape from each occupancy should not pass through any other occupancy.

b.If a common corridor or circulation space is on the escape route, one of the following should apply.

i.It should be a protected corridor.

ii.A suitable automatic fire detection and alarm system should be installed throughout the storey.

Width of escape routes and exits

2.18The width of escape routes and exits should meet the provisions in Table 2.3, as well as the guidance in Approved Document M.

2.19If the maximum number of people likely to use the escape route and exit is not known, it should be calculated using the occupant number guidance in Appendix D.

2.20Guidance on the spacing of fixed seating for auditoria is given in Annex D of BS 9999.

Source page 31

Calculating exit capacity

2.21Where multiple storey exits are available, fire might prevent one from being used. Remaining exits need to be wide enough for all occupants, so when using Table 2.3, the largest exit should be discounted.

Stairs should be at least as wide as any storey exit leading onto them. While some stairs are not subject to discounting (paragraphs 3.14 and 3.15), because the stairs will be available for other floors, the storey exits onto them are.

2.22To calculate how many people two or more available exits (after discounting) can accommodate, add together the maximum numbers of people that each exit width can accommodate.

For example, three exits each 850mm wide accommodate 3×110 = 330 people.

2.23If a ground floor storey exit and a stair share a final exit (via a ground floor lobby), then the final exit should be wide enough to evacuate people at a maximum flow rate equal to or greater than from the storey exit and stair combined (Diagram 2.6).

Source page 32

This can be calculated using the following formula:

W = ((N/2.5) + (60S))/80

where:

W is the width of final exit in metres

N is the number of people served by ground floor storey exit

S is the stair width in metres.

If the number of people (N) entering the lobby from the ground storey is more than 60, then the distance from the foot of the stair or the storey exit to the final exit should be a minimum of 2m (see Diagram 2.6).

If that minimum distance cannot be achieved, the width of the final exit (W) should be at least the width of the stair plus the width of the storey exit.

Worked example

A ground floor storey exit serving 250 people shares a common final exit with a 1.2m wide stair.

Required final exit width = ((250/2.5) + (1.2×60))/80 = 2.150m

Protected corridors

2.24A corridor serving as part of the means of escape in any of the following circumstances should be a protected corridor.

a.Every corridor that serves bedrooms.

b.Every dead end corridor (excluding recesses and extensions a maximum of 2m deep, as shown in Diagrams 2.7 and 2.8).

c.Any corridor shared by two or more occupancies (paragraph 2.17).

Source page 33

Source page 34

2.25If a corridor is used for a means of escape but is not a protected corridor, even though the enclosing partitions may have no fire resistance, both of the following should be met to inhibit the spread of smoke.

a.Partitions should continue to the soffit of the structural floor above, or to a suspended ceiling.

b.Openings into rooms from the corridor should be fitted with doors, which do not need to be fire doorsets.

Open planning will not inhibit the spread of smoke, but occupants can become aware of a fire quickly.

Division of corridors

2.26A corridor providing access to alternative escape route should be divided by fire doorsets fitted with a self-closing device (and associated screens) where both of the following apply.

a.It is more than 12m long.

b.It connects two or more storey exits.

The fire doorsets (including any screens) should be approximately mid-way between the two storey exits. They should safeguard the route from smoke, while considering the layout of the corridor and any adjacent fire risks.

2.27For buildings other than dwellings (purpose groups 2 to 7): if a cavity exists above the enclosures to a corridor as described above (because the enclosures are not carried to full storey height or the underside of the roof covering at the top storey), the potential for smoke to bypass the enclosure should be restricted by one of the following methods.

a.Method 1 – Fitting cavity barriers on the line of the enclosure(s) to and across the corridor (Diagram 2.9).

b.Method 2 – Dividing the storey using fire resisting construction that passes through the line of the division of the corridor (Diagram 2.9). Any cavity above this division should be fitted with cavity barriers on the line of division of the storey and the corridor.

c.Method 3 – Enclosing the cavity on the lower side by a fire resisting ceiling that extends throughout the building, compartment or separated part.

Any door that could provide a path for smoke to bypass the division should be fitted with a self-closing device (but need not necessarily be fire resisting).

Source page 35

Source page 36

2.28Where dead ends of corridors exceeding 4.5m long provide access to a point from which alternative escape route are available, they should be separated by self-closing fire doorsets (together with any associated screens) from any part of the corridor that either:

a.Provides two directions of escape (Diagram 2.10a)

b.Continues past one storey exit to another (Diagram 2.10b).

Alternatively, the stairs and corridors may be protected by a pressurisation system complying with BS EN 12101-6.

Cavity barriers

2.29Additional measures to safeguard means of escape from smoke are given in Section 10.

External escape routes

2.30Where an external escape route is beside an external wall of the building, the external wall should be of fire resisting construction in both of the following zones.

a.Within 1800mm of the escape route.

b.Up to 1100mm above the surface of the escape route.

This does not apply to external escape stairs (see paragraph 3.32).

Source page 37

2.31Where a storey or part of a building has multiple escape routes available, one may be over a flat roof if it does not serve a ‘residential (institutional)’ (purpose group 2(a)) building, or part of a building intended for use by members of the public.

2.32Where an escape route over a flat roof is provided, the roof should comply with all of the following.

a.It should be part of the same building from which escape is being made.

b.The route across the roof should lead to a storey exit or external escape route.

c.The part of the roof forming the escape route and its supporting structure, together with any opening within 3m of the escape route, should be fire resisting (minimum REI 30).

d.The route should be clearly defined and guarded by walls and/or protective barriers to protect from falling.

Residential care homes

General provisions

2.33The choice of fire safety strategy depends on the way a building is designed, furnished, staffed and managed, and on the level of dependency of the residents.

2.34In care homes for the elderly, some or all residents are likely to need help to evacuate. Buildings should generally be designed for progressive horizontal evacuation (PHE) in accordance with paragraphs 2.35 to 2.46.

For other care home types, the most appropriate of either a PHE or simultaneous evacuation strategy should be identified. The approach adopted in the design of a building must be recorded and communicated to the building management team, who can adopt procedures compatible with the building design.

Planning for progressive horizontal evacuation

2.35The guidance below on PHE is for care homes where the provisions of the Firecode documents do not apply (see paragraph 0.10).

PHE requires areas used for the care of residents to be divided into protected areas by compartment walls and compartment floors. Protected areas provide a place of relative safety, from which further evacuation can be made if necessary.

2.36Each storey used for the care of residents should be divided by compartment walls into at least three protected areas. All floors should be compartment floors.

2.37Every protected area should have a minimum of two exits to adjoining protected areas. Maximum travel distances within a protected area should be both of the following.

a.To the exit to the adjoining protected area: as shown in Table 2.1.

b.From any point to a storey exit or a final exit: 64m.

2.38A fire in one protected area should not prevent occupants of other areas from reaching a final exit (Diagram 2.11). Escape routes should not pass through ancillary accommodation listed in paragraph 2.44.

Source page 38

2.39The number of residents’ beds in protected areas should be based on an assessment of both of the following.

a.The number of staff likely to be available.

b.The level of assistance that residents may require.

The maximum number of residents’ beds in one protected area should not exceed 10, but may need to be lower depending on the assessment.

2.40A protected area used for horizontal evacuation from an adjoining protected area should have a floor area able to accommodate its own occupants plus those from the largest adjoining protected area.

Fire detection and alarm

2.41A fire detection and alarm system should be provided to L1 standard in accordance with BS 5839-1.

Bedrooms

2.42Each bedroom in a care home should be enclosed in fire resisting construction (minimum REI 30) with fire resisting doors (minimum E 30). Every corridor serving bedrooms should be a protected corridor (see paragraph 2.24).

Source page 39

2.43Bedrooms should not contain more than one single or double bed.

Ancillary accommodation

2.44Ancillary accommodation such as all of the following should be enclosed by fire resisting construction (minimum REI 30).

a.Chemical stores.

b.Cleaners’ rooms.

c.Clothes storage.

d.Day rooms.

e.Smoking rooms.

f.Disposal rooms.

g.Plant rooms.

h.Linen stores.

i.Kitchens.

j.Laundry rooms.

k.Staff changing and locker rooms.

l.Store rooms.

Door closing devices

2.45If doors fitted with a self-closing device could present an obstacle to residents, the following hardware in accordance with BS EN 1155 is appropriate.

a.Bedrooms: free-swing door closers.

b.Circulation spaces: hold-open devices.

Sprinkler systems

2.46Care homes should be fitted with a sprinkler system throughout the building in accordance with Appendix E.

Source page 40

Introduction

3.1The limits on horizontal travel escape distances mean most people should be able to independently reach a protected escape route or final exit. The following guidance also includes measures for people who are unable to use stairs without help.

In larger buildings, some escape stairs may need to serve as firefighting stairs, and Section 17 will also apply.

Number of escape stairs

Mixed use buildings

3.2If a building contains storeys, or parts of storeys, in different purpose groups, it is necessary to consider providing either of the following.

a.Separate escape routes from the areas of different use.

b.Other effective means to protect common escape routes.

Single escape stairs

3.3A single escape stair may serve a building (or part of a building) in the following situations.

a.When independent escape routes from areas in different purpose groups are not necessary (see paragraph 3.2).

b.From a basement that is allowed to have a single escape route in accordance with paragraph 2.6b and Table 2.1.

c.In small premises, provided it meets the conditions in paragraph 4.2.

d.From a building that meets both of the following conditions.

i.It has no storey with a floor level more than 11m above ground level.

ii.It is allowed to have only a single escape route in every storey in accordance with paragraph 2.6b and Table 2.1.

e.An office building with a maximum of five storeys above the ground storey where both of the following apply.

i.The travel distance from every point in each storey does not exceed the distances given in Table 2.1 for escape in one direction only.

ii.Every storey with a floor level more than 11m above ground level has an alternative means of escape.

Source page 41

f.A factory comprising no more than either of the following.

i.For low risk buildings, two storeys above the ground storey.

ii.For normal risk buildings, one storey above the ground storey, provided the travel distance from every point on each storey does not exceed the distances given in Table 2.1 for escape in one direction only.

g.Process plant buildings with a maximum of 10 people.

Provision of refuges

3.4Refuges form part of the management plan and offer relatively safe areas for people to wait for a short period only. Refuges should meet the following conditions.

a.Refuges should be provided on every storey (except ones consisting only of plant rooms) of each protected stairway providing an exit from that storey.

b.Refuges do not need to be located within the stair enclosure, but should enable direct access to the stair.

c.The number of refuge spaces does not need to equal the number of wheelchair users who may be in the building. A single refuge may be occupied by more than one person during the evacuation procedure.

3.5The following are both examples of satisfactory refuges.

a.An enclosure such as a compartment (Diagram 3.1), protected lobby, protected corridor or protected stairway (Diagram 3.2).

b.An area in the open air, such as a flat roof, balcony, podium or similar place, that meets both of the following.

i.It is protected (or remote) from any fire risk.

ii.It has its own means of escape.

3.6Refuges should be a minimum of 900mm × 1400mm in size and accessible by someone in a wheelchair. Where sited in a protected stairway, protected lobby or protected corridor, they should not reduce the width of the escape route or obstruct the flow of people escaping.

3.7Refuges should be provided with an emergency voice communication (EVC) system complying with BS 5839-9. It should consist of Type B outstations communicating with a master station in the building control room (if one exists) or next to the fire detection and alarm panel. In some buildings, wireless technology may be more appropriate.

3.8Refuges and evacuation lifts should be clearly identified. In protected lobbies and protected stairways there should be a blue mandatory sign worded ‘Refuge – keep clear’ in addition to fire safety signs.

3.9Paragraph 5.32 gives guidance on using lifts, including evacuation lifts, during a fire.

Source page 42

Width of escape stairs

3.10The width of escape stairs should meet all of the following conditions.

a.It should be at least as wide as any exits giving access to the stairs.

Source page 43

b.It should be no less than the minimum widths given in Table 3.1.

c.It should not reduce at any point on the way to a final exit.

d.It should not exceed 1400mm in stairs taller than 30m, unless a central handrail is provided. When a central handrail is provided, the stair width on each side of it should be considered separately when assessing stair capacity.

3.11Approved Document K requires stairs more than 2000mm wide in public buildings to have a central handrail.

3.12If an exit route from a stair is also the escape route from the ground storey and/or basement storey, the width of the exit route may need to be increased (see paragraph 2.23).

Calculation of minimum stair width

3.13The width depends on the number of stairs provided and the escape strategy (simultaneous or phased evacuation). If the maximum number of people needing to use escape stairs is unknown, calculate it using the floor space factors in Appendix D.

Discounting of stairs

3.14Regardless of escape strategy, where two or more stairs are provided, it should be assumed that one might not be available during a fire. Each stair should be discounted in turn to ensure the capacity of the remaining stairs is adequate. This applies to buildings with or without a sprinkler system.

3.15Paragraph 3.14 does not apply if either of the following applies.

a.Escape stairs are protected by a smoke control system designed in accordance with BS EN 12101-6.

b.Escape stairs are approached on each storey (except the top storey) through a protected lobby.

Despite these exceptions, at least one storey exit still needs to be discounted (paragraph 2.21).

Source page 44

Paragraph 3.34 identifies cases where stairs need lobby protection.

Simultaneous evacuation

3.16The width of escape stairs should take account of the number of people using them while evacuating all storeys at the same time. The following stairs should be designed to allow simultaneous evacuation.

a.All stairs serving basements.

b.All stairs serving buildings with open spatial planning.

c.All stairs serving ‘residential (other)’ (purpose group 2(b)) or ‘assembly and recreation’ (purpose group 5) buildings.

Annexes B and C of BS 9999 include designs based on simultaneous evacuation.

3.17The capacity of stairs of widths from 1000mm to 1800mm is given in Table 3.2.

3.18As an alternative to Table 3.2, the capacity of stairs 1100mm wide or wider can be found using either of the following formulas:

a.P = 200W + 50 (W − 0.3)(N − 1)

b.W = P + 15N − 15 / 150 + 50N

where:

Source page 45

P is the number of people that can be served

W is the width of the stair, in metres

N is the number of storeys served.

Separate calculations should be made for stairs serving basement storeys and stairs serving upper storeys.

The population, P, should be divided by the number of available stairs.

The formula is useful to determine the width of stairs where people are not distributed evenly – either within a storey or between storeys.

In the formula, 200W represents the number of people estimated to have left the stair after 2.5 minutes of evacuation, and 50 (W − 0.3)(N − 1) represents the number of people estimated to be on the stair after 2.5 minutes of evacuation.

Worked examples

A 14 storey building contains 12 storeys of offices (ground + 11). The top two storeys contain flats that are served by separate stairs. What is the minimum width needed for the stairs that serve the office floors, for simultaneous evacuation? In the 11 above-ground-floor offices, 1200 people use the stairs. (People in the ground floor offices do not use the stairs.) In this example, two stairs are shown to satisfy the travel distance limitations.

a. The population is distributed evenly

The top office storey is at a height greater than 18m, therefore both stairs need lobby protection (see paragraph 3.34). Because both stairs are entered at each level via a protected lobby, both stairs can be assumed to be available (see paragraph 3.15).

P = 1200/2 = 600, N = 11

From the formula:

600 = 200W + 50 (W − 0.3)(11 − 1)

600 = 200W + (50W − 15)(10)

600 = 200W + 500W − 150

750 = 700W

W = 1070mm

Therefore both stairs should be at least 1070mm wide. But this needs to be increased to 1100mm, because the formula applies to stairs 1100mm wide or wider (see paragraph 3.18).

This width will also be adequate when one storey exit is discounted as described in paragraph 2.21. It also complies with paragraph 3.10a (i.e. the stair widths are not less than the minimum widths needed for 110 people in Table 2.3).

b. The population is not distributed evenly

(e.g. 1000 people occupy floors 1 to 9, and 200 occupy floors 10 and 11).

The top office storey is at a height greater than 18m, therefore both stairs need lobby protection (see paragraph 3.34). Because both stairs are entered at each level via a protected lobby, both stairs can be assumed to be available (see paragraph 3.15).

Source page 46

To find the width of:

•the stairs serving floors 10 and 11:

P = 200/2 = 100, N = 2

From the formula:

100 = 200W + 50 (W − 0.3)(2 − 1)

100 = 200W + (50W − 15)(1)

100 = 200W + 50W − 15

115 = 250W

W = 460mm

Therefore both stairs between the 9th floor landing and the top floor should be at least 460mm wide. But this needs to be increased to 1100mm, because the formula applies to stairs 1100mm wide or wider (see paragraph 3.18).

This width will also be adequate when one storey exit is discounted as described in paragraph 2.21. It also complies with paragraph 3.10a (i.e. the stair widths are not less than the minimum widths needed for 100 people in Table 2.3).

•the stairs serving floors 1 to 9:

P = 1200/2 = 600, N = 9

From the formula:

600 = 200W + 50 (W − 0.3)(9 − 1)

600 = 200W + (50W − 15)(8)

600 = 200W + 400W − 120

720 = 600W

W = 1200mm

Therefore both stairs between the ninth floor landing and the ground floor should be at least 1200mm wide.

This width will also be adequate when one storey exit is discounted as described in paragraph 2.21. It also complies with paragraph 3.10a (i.e. the stair widths are not less than the minimum widths needed for 134 people in Table 2.3).

Phased evacuation

3.19Phased evacuation cannot be used in every type of building, but can be advantageous for escape stairs in high buildings. It requires supporting facilities, such as fire detection and alarm systems, to be provided and maintained.

In a phased evacuation, the first people to be evacuated are those with reduced mobility and those on the storey most immediately affected by the fire. If needed, subsequent evacuation is done two floors at a time, reducing disruption in large buildings.

Phased evacuation enables stairs to be narrower than with simultaneous evacuation, and may be used for any building provided it is not identified in paragraph 3.16.

Source page 47

3.20Phased evacuation in buildings with a storey over 30m in height introduces the potential for escaping people to impede firefighters entering and operating within the building. This can be addressed by consulting with the fire and rescue service about special management procedures.

In very tall buildings, typically with a storey over 45m in height, physical measures may need to be incorporated, such as by discounting a stair.

3.21A building (or part of a building) designed for phased evacuation should satisfy all of the following criteria.

a.At each storey except a top storey, stairs should be approached through a protected lobby or protected corridor.

b.At each storey, the lifts should be approached through a protected lobby (see paragraph 5.37).

c.Every floor should be a compartment floor (REI depending on height and use of the building).

d.If there is a storey over 30m above ground level, the building should be protected throughout by an automatic sprinkler system in accordance with Appendix E.

e.The building should be fitted with an appropriate fire warning system conforming to at least the L3 standard given in BS 5839-1.

f.An internal speech communication system should provide communication between a control point at fire and rescue service access level and a fire warden on every storey. The recommendations for phased evacuation provided in BS 5839-1 should be followed. Where it is deemed appropriate to install a voice alarm, this should be in accordance with BS 5839-8.

3.22The minimum width of stairs needed for phased evacuation is given in Table 3.3.

Source page 48

What is the minimum width needed for the stairs serving a 15 storey office building (ground + 14 office floors), assuming a total population of 2500 people (excluding the ground floor population, which does not use the stairs)? To satisfy the travel distance limitations, three stairs are required.

The building is over 45m in height and designed for phased evacuation. It has been decided to discount one stair to take account of fire and rescue service operations as described in paragraph 3.20. Therefore:

•Number of people per storey = 2500/14 = 179.

Each remaining stair must be able to accommodate half the population of one storey (i.e. 90 people).

Thus each stair should be 1000mm wide (maximum capacity 100 people).

This width will also be adequate when one storey exit is discounted as described in paragraph 2.21. It also complies with paragraph 3.10a (i.e. the stair widths are not less than the minimum width needed for 90 people in Table 2.3).

•At least one of those stairs needs to be a firefighting stair, therefore a minimum width of 1100mm is needed (see note 2 to Table 3.1).

Additional worked example using Table 3.3

What is the minimum width needed for the stairs serving a 9 storey office building (ground + 8 office floors), assuming a total population of 1920 people (excluding the ground floor population, which does not use the stairs)? To satisfy the travel distance limitations, two stairs are required.

As both stairs need to be entered at each level through a protected lobby (see paragraph 3.21), both stairs can be assumed to be available (see paragraph 3.15). Therefore:

•Number of people per storey = 1920/8 = 240.

•Each stair must be able to accommodate half the population of one storey (i.e. 240/2 = 120 people).

•Thus both stairs would require a width of 1100mm (maximum capacity 120 people) according to Table 3.3, but:

•Each storey exit needs to be able to serve 240 people, because of discounting as described in paragraph 2.21. The minimum exit width needed for 240 people in Table 2.3 is 1200mm. As described in paragraph 3.10a, the stair should be at least as wide as the storey exit it is serving.

•The required stair width is therefore 1200mm.

Design and protection of escape stairs

Enclosure of escape stairs

3.23Every internal escape stair should be a protected stairway (within a fire resisting enclosure). If it is also a protected shaft (i.e. it passes from one compartment to another) or firefighting shaft, additional guidance in Sections 8 and 17 applies.

There is one exception: an unprotected stair (e.g. an accommodation stair) may form part of an internal route to a storey exit or final exit, provided that the distance of travel and the number of people involved are very limited. For example, small premises (Section 4) and raised storage areas (see paragraphs 7.6 and 7.7).

Source page 49

3.24The flights and landings of escape stairs should be constructed of materials achieving class A2-s3, d2 or better in all of the following situations.

a.If the escape stair is the only stair serving the building or part of the building, unless the building has two or three storeys and is an office building.

b.If the escape stair is within a basement storey.

c.If the escape stair serves any storey that has a floor level more than 18m above ground or access level.

d.If the escape stair is external, except where the stair connects the ground floor or ground level with a floor or flat roof a maximum of 6m above or below ground level.

e.If the escape stair is a firefighting stair.

Materials achieving class B-s3, d2 or worse may be added to the top horizontal surface, except on firefighting stairs.

3.25Further guidance on firefighting stairs is given in Section 17. Dimensional constraints on the design of stairs are given in Approved Document K.

Single steps

3.26Single steps on escape routes should be prominently marked. A single step on the line of a doorway is acceptable, subject to paragraph 5.22.

Helical stairs and spiral stairs

3.27Helical stairs and spiral stairs may form part of an escape route provided they are designed in accordance with BS 5395-2. If they are intended to serve members of the public, stairs should be type E (public) stairs.

Fixed ladders

3.28Fixed ladders should not be provided as a means of escape for members of the public. They should only be provided where a conventional stair is impractical, such as for access to plant rooms which are not normally occupied.

External walls adjacent to protected stairways

3.29With some configurations of external wall, a fire in one part of a building could subject the external wall of a protected stairway to heat (for example, where the two are adjacent at an internal angle in the façade, as shown in Diagram 3.3).

3.30If a protected stairway projects beyond, is recessed from or is in an internal angle of the adjoining external wall of the building, then the minimum distance between an unprotected area of the building enclosure and an unprotected area of the stair enclosure should be 1800mm.

Source page 50

External escape stairs

3.31Where a storey or part of the building has more than one escape route available, some of the escape routes may be via an external escape stair, provided the following conditions are met.

a.There is at least one internal escape stair from every part of each storey (excluding plant areas).

b.In the case of an ‘assembly and recreation’ (purpose group 5) building, the route is not intended for use by the public.

c.In the case of a ‘residential (institutional)’ (purpose group 2(a)) building, the route serves only office or residential staff accommodation.

3.32Any external escape stair should meet all of the following conditions (Diagram 3.4).

a.Doors to the stair should be fire resisting (minimum E 30) and be fitted with a self-closing device, except for a single exit door from the building to the top landing of a downward-leading external stair, provided it is the only door onto the landing.

b.Fire resisting construction (minimum RE 30) is required for the building envelope within the following zones, measured from the flights and landings of the external stair.

i.1800mm above and horizontally.

ii.9m vertically below.

iii.1100mm above the top landing of the stair (except where the stair leads from basement to ground level).

c.Fire resisting construction (minimum RE 30) should be provided for any part of the building (including doors) within 1800mm of the escape route from the foot of the stair to a place of safety. This does not apply if there are alternative escape route from the foot of the external escape stair.

d.Stairs more than 6m in height should be protected from adverse weather. Protection should prevent the build-up of snow or ice but does not require full enclosure.

Source page 51

e.Glazing in areas of fire resisting construction should be fixed shut and fire resisting, in terms of integrity but not insulation (minimum E 30).

3.33Access to an external escape stair may be via a flat roof, provided the flat roof meets the requirements of paragraphs 2.31 and 2.32.

Source page 52

3.34In the following situations, protected lobbies or protected corridors should be provided at all storeys above ground, except the top storey.

a.If the stair is the only one serving a building or part of a building that has more than one storey above or below the ground storey.

b.If the stair serves any storey at a height of 18m or more above ground level.

c.If the building is designed for phased evacuation.

d.If the stair is a firefighting stair.

e.If the option in paragraph 3.15b has been used so as not to discount one stair when calculating stair widths.

As an alternative to (a) to (c), a smoke control system as described in paragraph 3.15a may be used.

3.35A protected lobby should be provided between an escape stair and a place of special fire hazard to protect from the ingress of smoke. The lobby should have a minimum 0.4m² of permanent ventilation, or be protected by a mechanical smoke control system.

Exits from protected stairways

3.36Every protected stairway should lead to a final exit, either directly or via an exit passageway. Any protected exit corridor or stair should have the same standard of fire resistance and lobby protection as the stair it serves. The exit from a protected stairway should comply with paragraphs 5.20 to 5.24.

Separation of adjoining protected stairways

3.37The construction separating two adjacent protected stairways (or exit passageways) leading to different final exits should be imperforate.

Use of space within protected stairways

3.38A protected stairway may only include any of the following.

a.Sanitary accommodation or washrooms, as long as the accommodation is not used as a cloakroom. A gas water heater or sanitary towel incinerator may be installed in the accommodation, but no other gas appliance.

b.If the protected stairway is not a firefighting stair: a lift well.

c.If the protected stairway is not the only stair serving the building or part of the building: a reception desk or enquiry office area at ground or access level. The reception or enquiry office area should have a maximum area of 10m².

d.If the protected stairway is not the only stair serving the building or part of the building: cupboards enclosed with fire resisting construction.

Source page 53

3.39Gas service and installation pipes and meters should not be within a protected stairway, unless installed in accordance with the Pipelines Safety Regulations 1996 and the Gas Safety (Installation and Use) Regulations 1998.

Basement stairs

3.40An escape stair forming part of the only escape route from an upper storey should not continue down to serve a basement storey. The basement storey should be served by a separate escape stair.

3.41Where multiple escape stairs serve the upper storeys, only one needs to end at ground level. Other stairs may connect with the basement storeys if there is a protected lobby or a protected corridor between the stairs and accommodation at each basement level.

Source page 54

4.1A ‘small premises’ is generally limited both in its size and in its number of occupants. When undivided, all of its parts are likely to be clearly visible to occupants. Occupants of small premises will be able to reach an exit quickly in an emergency and therefore a reduction in the number of exits and stairs is acceptable.

This guidance is not applicable to small premises where highly flammable materials are sold, stored or used.

4.2Small premises should meet all of the following general conditions.

i.It should be single occupancy.

ii.It should not comprise more than a basement storey, ground storey and first storey.

iii.No storey should have a floor area more than 280m².

b.Any kitchen or other open cooking arrangements should be at the extremity of any dead end remote from the exits.

c.For a bar or restaurant, the seating or standing accommodation (Table D1) should be planned for a maximum of 30 people per storey. The seating or standing accommodation for the ground storey may be planned for 100 people if it has a final exit independent of the stair.

4.3The following paragraphs only apply in place of those provisions elsewhere in this Approved Document which relate to the following.

a.The number and position of exits and protected stairways.

b.Measuring distances of travel.

c.Open escape stairs.

For provisions other than those listed above, the guidance elsewhere in this Approved Document should be followed.

Construction

4.4Except in kitchens, ancillary offices and stores, floor areas should be undivided so exits are clearly visible from all parts.

4.5Store rooms should be enclosed with fire resisting construction (minimum REI 30).

Travel distance and number of escape routes

4.6Escape routes should be sited so that the travel distance from any point of a storey to the nearest storey exit does not exceed the distance given in Table 4.1 (see Diagrams 4.1, 4.2 and 4.3). The siting of two or more exits or stairs should give effective alternative directions of travel from any point in a storey.

Source page 55

Source page 56

Source page 57

1.Maximum floor area in any one storey 90m².

2.Enclosed stair at ground storey level may be from either the basement or the first storey.

3.The premises may not be used as a restaurant or bar.

4.Travel distances are set out in Table 4.1.

Source page 58

4.7A single escape stair may be used in small premises.

4.8An open stair may be used as a means of escape if all of the following apply.

a.The stair connects a maximum of two storeys.

b.The stair enters the ground storey a maximum of 3m from the final exit (see Diagrams 4.2 and 4.3).

c.The premises is not a bar or restaurant.

d.Either of the following applies.

i.The storey is also served by a protected stairway.

ii.The stair is a single stair and the floor area of any single storey is a maximum of 90m².

4.9Where the premises contains three storeys and a single open stair serves a top or bottom storey, the stair serving the other storey should be enclosed with fire resisting construction at the ground storey level and discharge to a final exit independent of the ground storey (see Diagram 4.3).

Source page 59

Introduction

5.1This section applies to all buildings and deals with the design, construction and protection of escape routes and service installations.

Protection of escape routes

Fire resistance of enclosures

5.2Fire resistance test criteria are set out in Appendix B. Standards of performance are summarised in Table B1 and Table B2. Apart from specific situations described in Sections 1 and 2, and requirements B3 and B5, a minimum performance of REI 30 is sufficient to protect means of escape.

Fire resistance of doors

5.3Fire resistance test criteria are set out in Appendix C. Standards of performance are summarised in Table C1.

Fire resistance of glazed elements

5.4If glazed elements in fire resisting enclosures and doors can only meet the required integrity performance, their use is limited. These limitations depend on whether the enclosure forms part of a protected shaft (see Section 8) and the provisions set out in Appendix B, Table B3. If both integrity and insulation performance can be met, there is no restriction in this document on the use or amount of glass.

5.5Glazed elements should also comply with the following, where necessary.

a.If the enclosure forms part of a protected shaft: Section 8.

b.Appendix B, Table B3.

c.Guidance on the safety of glazing: Approved Document K.

Doors on escape routes

5.6Doors should be readily openable to avoid undue delay to people escaping. Doors on escape routes (both within and from the building) should comply with paragraphs 5.7 to 5.15. Guidance on door closing and ‘hold open’ devices for fire doorsets is set out in Appendix C.

Door fastenings

5.7In general, doors on escape routes (whether or not the doors are fire doorsets) should be either of the following.

a.Not fitted with a lock, latch or bolt fastenings.

b.Fitted only with simple fastenings that are all of the following.

i.Easy to operate; it should be apparent how to undo the fastening.

Source page 60

ii.Operable from the side approached by people escaping.

iii.Operable without a key.

iv.Operable without requiring people to manipulate more than one mechanism.

Doors may be fitted with hardware to allow them to be locked when rooms are empty.

In places such as hotel bedrooms, locks may be fitted that are key operated from the outside and manually opened from the inside.

If a secure door is operated by code or combination keypad, swipe or proximity card, biometric data, etc., a security mechanism override should be possible from the side approached by people escaping.

5.8Electrically powered locks should return to the unlocked position in all of the following situations.

a.If the fire detection and alarm system operates.

b.If there is loss of power or system error.

c.If the security mechanism override is activated.

Security mechanism overrides for electrically powered locks should be a Type A call point as described in BS 7273-4. The call point should be positioned on the side approached by people escaping. If the door provides escape in either direction, a call point should be installed on both sides of the door.

5.9In places of assembly and shop and commercial buildings (purpose groups 4 and 5), doors on escape routes from rooms with more than 60 people should be either of the following.

a.Not fitted with locks, latches or bolts.

b.Fitted with panic fastenings in accordance with BS EN 1125.

In non-residential buildings (purpose groups 3 to 7), some final exit doors feature security locks that are used only when the building is empty. Such locks may be appropriate, but management procedures must emphasise their safe use.

5.10Guidance on door closing and ‘hold open’ devices for fire doorsets is set out in Appendix C.

Direction of opening

5.11The door of any doorway or exit should be hung to open in the direction of escape whenever reasonably practicable. It should always be hung to open in the direction of escape if either of the following conditions applies.

a.More than 60 people might be expected to use it during a fire.

b.There is a very high risk of fire with potential for rapid fire growth, such as with some industrial activities.

Amount of opening and effect on associated escape routes

5.12All doors on escape routes should be hung to meet both of the following conditions.

a.Open by a minimum of 90 degrees.

b.Open with a swing that complies with both of the following.

i.Is clear of any change of floor level, other than a threshold or single step on the line of the doorway.

ii.Does not reduce the effective width of any escape route across a landing.

Source page 61

5.13Any door opening towards a corridor or a stair should be recessed to prevent its swing encroaching on the effective width.

Vision panels in doors

5.14Doors should contain vision panels in both of the following situations.

a.Where doors on escape routes divide corridors.

b.Where doors are hung to swing both ways.

Approved Document M contains guidance about vision panels in doors across accessible corridors and Approved Document K contains guidance about the safety of glazing.

Revolving and automatic doors

5.15Where revolving doors, automatic doors and turnstiles are placed across escape routes they should comply with one of the following.

a.They are automatic doors of the required width and comply with one of the following conditions.

i.Their failsafe system provides outward opening from any open position.

ii.They have a monitored failsafe system to open the doors if the mains electricity supply fails.

iii.They failsafe to the open position if the power fails.

b.Non-automatic swing doors of the required width are provided immediately adjacent to the revolving or automatic door or turnstile.

General provisions

Headroom in escape routes

5.16Escape routes should have a minimum clear headroom of 2m. The only projections allowed below this height are door frames.

Flooring of escape routes

5.17Escape route floor finishes should minimise their slipperiness when wet. Finishes include the treads of steps and surfaces of ramps and landings.

Ramps and sloping floors

5.18A ramp forming part of an escape route should meet the provisions in Approved Document M. Any sloping floor or tier should have a pitch of not more than 35 degrees to the horizontal.

5.19Guidance for where there is fixed seating is given in both of the following.

a.Approved Documents K and M give guidance on the design of ramps and associated landings, and on aisles and gangways where there is fixed seating.

b.Section 2 of this document refers to Annex D of BS 9999, which gives guidance on the design of means of escape in places with fixed seating.

Final exits

5.20The width of a final exit should be at least the same as the minimum required width of the escape route it serves.

Source page 62

5.21People should be able to rapidly leave the area around the building. Direct access to a street, passageway, walkway or open space should be available. The route away from the building should comply with the following.

a.Be well defined.

b.If necessary, have suitable guarding.

5.22Final exits should not present a barrier for disabled people. Where the route to a final exit does not include stairs, a level threshold and, where necessary, a ramp should be provided.

5.23Final exit locations should be clearly visible and recognisable.

5.24Final exits should avoid outlets of basement smoke vents and openings to transformer chambers, refuse chambers, boiler rooms and similar risks.

Source page 63

5.25All escape routes should have adequate artificial lighting. If the mains electricity power supply fails, escape lighting should illuminate the routes listed in Table 5.1.

5.26Escape stair lighting should be on a separate circuit from the electricity supply to any other part of the escape route.

5.27Escape lighting should conform to BS 5266-1.

Exit signs

5.28Every doorway or other exit providing access to a means of escape, other than exits in ordinary use (e.g. main entrances), should be distinctively and conspicuously marked by an exit sign in accordance with BS ISO 3864-1 and BS 5499-4.

Advice on fire safety signs, including emergency escape signs, is given in the HSE publication Safety Signs and Signals: Guidance on Regulations.

Some buildings may require additional signs to comply with other legislation.

Protected power circuits

5.29To limit potential damage to cables in protected circuits, all of the following should apply.

a.Cables should be sufficiently robust.

b.Cable routes should be carefully selected and/or physically protected in areas where cables may be exposed to damage.

c.Methods of cable support should be class A1 rated and offer at least the same integrity as the cable. They should maintain circuit integrity and hold cables in place when exposed to fire.

5.30A protected circuit to operate equipment during a fire should achieve all of the following.

a.Cables should achieve PH 30 classification when tested in accordance with BS EN 50200 (incorporating Annex E) or an equivalent standard.

b.It should only pass through parts of the building in which the fire risk is negligible.

c.It should be separate from any circuit provided for another purpose.

5.31Guidance on cables for large and complex buildings is given in BS 5839-1, BS 5266-1 and BS 8519.

Lifts

Evacuation lifts

5.32Generally, lifts should not be used when there is a fire in the building, unless their use forms part of a management plan for evacuating people and the following conditions are met.

a.Lifts are appropriately sited and protected.

b.Lifts contain safety features to ensure they remain usable during a fire.

Guidance on the design and use of evacuation lifts is given in Annex G to BS 9999.

5.33Where a firefighting lift is provided, it can be used to evacuate disabled people. Management plans should describe how this would be managed, and what will happen when the fire and rescue service arrives.

Source page 64

5.34Lift wells should comply with one of the following conditions.

a.Be sited within the enclosures of a protected stairway.

b.Be enclosed with fire resisting construction (minimum REI 30) when in a position that might prejudice the means of escape.

5.35A lift well connecting different compartments should form a protected shaft (see Section 8).

5.36Lifts that rise within a large volume such as a mall or atrium and do not have a conventional well, such as wall-climber or feature lifts, may be at risk if they run through a smoke reservoir. Care should be taken to maintain the integrity of the smoke reservoir and protect people in the lift.

5.37In buildings designed for phased evacuation or progressive horizontal evacuation, if the lift well is not within the enclosures of a protected stairway, its entrance should be separated at every storey by a protected lobby (minimum REI 30).

5.38In basements and enclosed car parks, the lift should be within the enclosure of a protected stairway. Otherwise, the lift should be approached only via a protected lobby or protected corridor (minimum REI 30).

5.39If a lift delivers into a protected corridor or protected lobby serving sleeping accommodation and also serves a storey containing a high fire risk (such as a kitchen, communal areas, stores, etc.) then the lift should be separated from the high fire risk area(s) by a protected lobby or protected corridor (minimum REI 30).

5.40A lift shaft serving storeys above ground level should not serve any basement if either of the following applies.

a.There is only one escape stair serving storeys above ground level and smoke from a basement fire would adversely affect escape routes in the upper storeys.

b.The lift shaft is within the enclosure to an escape stair that terminates at ground level.

5.41Lift machine rooms should be sited over the lift well where possible. Where buildings or part of a building with only one stairway make this arrangement impractical, the lift machine room should be sited outside the protected stairway.

Refuse chutes and storage

5.42Refuse storage chambers, refuse chutes and refuse hoppers should be sited and constructed in accordance with BS 5906.

5.43Refuse chutes and rooms for storing refuse should meet both of the following conditions.

a.Be separated from other parts of the building by fire resisting construction (minimum REI 30 in buildings with a top storey up to 5m above ground level; otherwise REI 60).

b.Not be situated within a protected stairway or protected lobby.

5.44The approach to rooms containing refuse chutes or for storing refuse should comply with one of the following conditions.

a.Be directly from the open air.

b.Be through a protected lobby with a minimum 0.2m² of permanent ventilation.

5.45Access openings to refuse storage chambers should not be sited next to escape routes or final exits.

Source page 65

5.46Fully enclosed walk-in store rooms should be separated from retail areas with fire resisting construction (minimum REI 30) if they negatively affect the means of escape. The fire resisting construction is not necessary if the walk-in store room complies with either of the following.

a.Has an automatic fire detection and alarm system.

b.Is fitted with sprinklers.

Source page 66

This section deals with the following requirement from Part B of Schedule 1 to the Building Regulations 2010.

Intention

In the Secretary of State’s view, requirement B2 is met by achieving a restricted spread of flame over internal linings. The building fabric should make a limited contribution to fire growth, including a low rate of heat release.

It is particularly important in circulation spaces, where linings may offer the main means by which fire spreads and where rapid spread is most likely to prevent occupants from escaping.

Requirement B2 does not include guidance on the following.

a.Generation of smoke and fumes.

b.The upper surfaces of floors and stairs.

c.Furniture and fittings.

Source page 67

Classification of linings

6.1The surface linings of walls and ceilings should meet the classifications in Table 6.1.

Walls

6.2For the purposes of this requirement, a wall includes both of the following.

a.The internal surface of internal and external glazing (except glazing in doors).

b.Any part of a ceiling which slopes at an angle greater than 70 degrees to the horizontal.

6.3For the purposes of this requirement, a wall does not include any of the following.

a.Doors and door frames.

b.Window frames and frames in which glazing is fitted.

c.Architraves, cover moulds, picture rails, skirtings and similar narrow members.

d.Fireplace surrounds, mantle shelves and fitted furniture.

6.4Parts of walls in rooms may be of lower performance than stated in Table 6.1, but no worse than class D-s3, d2. In any one room, the total area of lower performance wall lining should be less than an area equivalent to half of the room’s floor area, up to a maximum of:

a.20m² in residential accommodation.

b.60m² in non-residential accommodation.

Ceilings

6.5For the purposes of this requirement, a ceiling includes all of the following.

a.Glazed surfaces.

b.Any part of a wall at 70 degrees or less to the horizontal.

Source page 68

c.The underside of a gallery.

d.The underside of a roof exposed to the room below.

6.6For the purposes of this requirement, a ceiling does not include any of the following.

a.Trap doors and their frames.

b.The frames of windows or rooflights and frames in which glazing is fitted.

c.Architraves, cover moulds, picture rails, exposed beams and similar narrow members.

Fire resisting ceilings

6.7The need for cavity barriers in concealed floor or roof spaces can be reduced by installing a fire resisting ceiling (minimum EI 30) below the cavity, complying with Diagram 9.3.

Rooflights

6.8Rooflights should meet the following classifications, according to material. No guidance for European fire test performance is currently available, because there is no generally accepted test and classification procedure.

a.Non-plastic rooflights should meet the relevant classification in Table 6.1.

b.Plastic rooflights, if the limitations in Table 6.2 and Table 14.2 are observed, should be a minimum class D-s3, d2 rating. Otherwise they should meet the relevant classification in Table 6.1.

Special applications

6.9Any flexible membrane covering a structure, other than an air-supported structure, should comply with Appendix A of BS 7157.

6.10Guidance on the use of PTFE-based materials for tension-membrane roofs and structures is given in BRE report BR 274.

Fire behaviour of insulating core panels used internally

6.11Insulating core panels consist of an inner core of insulation sandwiched between, and bonded to, a membrane, such as galvanised steel or aluminium.

Where they are used internally they can present particular problems with regard to fire spread, and should meet all of the following conditions.

a.Panels should be sealed to prevent exposure of the core to a fire. This includes at joints and where services penetrate the panel.

b.In high fire risk areas, such as kitchens, places of special fire hazard, or in proximity to where hot works occur, only class A1 cored panels should be used.

c.Fixing systems for all panels should be designed to take account of the potential for the panel to delaminate. For instance, where panels are used to form a suspended ceiling, the fixing should pass through the panel and support it from the lower face.

Source page 69

6.12Guidance on the control of flame spread is given in the following sections.

a.Stairs and landings: Section 3 (escape stairs) and Section 17 (firefighting shafts).

b.Section 9: exposed surfaces above fire-protecting suspended ceilings.

Thermoplastic materials

General provisions

6.13Thermoplastic materials that do not meet the classifications in Table 6.1 can be used as described in paragraphs 6.14 to 6.18. No guidance for European fire test performance is currently available, because there is no generally accepted test and classification procedure. Thermoplastic materials are defined in Appendix B, paragraph B11. Classifications used here are explained in paragraph B13.

Windows

6.14Thermoplastic material classified as a TP(a) rigid product may be used to glaze external windows to rooms, but not external windows to circulation spaces. Approved Document K includes guidance on the safety of glazing.

Rooflights

6.15In rooms and circulation spaces other than protected stairways, rooflights may be constructed of thermoplastic material if they comply with both of the following.

a.The lower surface is classified as TP(a) rigid or TP(b).

b.The size and location of the rooflights follow the limits in Table 6.2 and in Table 14.2 and Table 14.3.

Lighting diffusers

6.16The following paragraphs apply to lighting diffusers forming part of a ceiling. Diffusers may be part of a luminaire or used below sources of light. The following paragraphs do not apply to diffusers of light fittings attached to the soffit of a ceiling or suspended beneath a ceiling (Diagram 6.1).

Source page 70

6.17Diffusers constructed of thermoplastic material may be incorporated in ceilings to rooms and circulation spaces, but not to protected stairways, if both of the following conditions are met.

a.Except for the upper surfaces of the thermoplastic panels, wall and ceiling surfaces exposed in the space above the suspended ceiling should comply with paragraph 6.1.

b.Diffusers should be classified as one of the following.

i.TP(a) rigid – no restrictions on their extent.

ii.TP(b) – limited in their extent (see Table 6.2 and Diagram 6.2).

Suspended or stretched-skin ceilings

6.18A ceiling constructed from TP(a) flexible panels should meet the following conditions.

a.Have a maximum area of 5m².

b.Be supported on all sides.

1.Upper and lower surfaces of suspended ceiling, between plastic panels, to comply with paragraph 6.1.

2.No restriction on class D-s3, d2 diffusers or rooflights in small rooms.

3.See note 4 to Table 6.2.

Source page 71

Source page 72

Source page 73

These sections deal with the following requirement from Part B of Schedule 1 to the Building Regulations 2010.

Source page 74

In the Secretary of State’s view, requirement B3 is met by achieving all of the following.

a.For defined periods, loadbearing elements of structure withstand the effects of fire without loss of stability.

b.Compartmentation of buildings by fire resisting construction elements.

c.Automatic fire suppression is provided where it is necessary.

d.Protection of openings in fire-separating elements to maintain continuity of the fire separation.

e.Inhibition of the unseen spread of fire and smoke in cavities, to reduce the risk of structural failure and spread of fire and smoke, where they pose a threat to the safety of people in and around the building.

The extent to which any of these measures are necessary is dependent on the use of the building and, in some cases, its size, and on the location of the elements of construction.

Source page 75

Fire resistance standard

7.1Elements of structure such as structural frames, beams, columns, loadbearing walls (internal and external), floor structures and gallery structures should have, as a minimum, the fire resistance given in Appendix B, Table B1.

7.2Appendix B includes guidance on all of the following.

a.Provisions to ensure that where one element of structure supports or stabilises another element of structure, the supporting element has no less fire resistance than the other element (see Table B2).

b.Measures so that elements common to more than one building or compartment are constructed to the standard of the more onerous of the relevant provisions.

c.Special provisions about fire resistance of elements of structure in single storey buildings.

d.Concessions in respect of fire resistance of elements of structure in basements where one or more sides of the basement are open at ground level.

Exclusions from the provisions for elements of structure

7.3The following are excluded from the definition of ‘element of structure’.

a.A structure that supports only a roof, unless either of the following applies.

i.The roof performs the function of a floor, such as for parking vehicles, or as a means of escape.

ii.The structure is essential for the stability of an external wall that needs to be fire resisting (e.g. to achieve compartmentation or for the purposes of preventing fire spread between buildings).

b.The lowest floor of the building.

c.A platform floor.

d.A loading gallery, fly gallery, stage grid, lighting bridge or any gallery provided for similar purposes or for maintenance and repair.

e.External walls, such as curtain walls or other forms of cladding, which transmit only self weight and wind loads and do not transmit floor load.

Source page 76

7.4If a loadbearing wall is any of the following, guidance in other sections may also apply.

a.A compartment wall (including a wall common to two buildings): Section 8.

b.Enclosing a place of special fire hazard: Section 8, paragraph 8.7.

c.Protecting a means of escape: Sections 2 to 5.

d.An external wall: Sections 12 and 13.

e.Enclosing a firefighting shaft: Section 17.

7.5If a floor is also a compartment floor, see Section 8.

Raised storage areas

7.6The normal provisions for fire resistance may be too onerous to apply to raised, free-standing floors (sometimes supported by racking) in single storey buildings used for industrial and storage purposes. The introduction of raised storage areas can alter the effective number of storeys in the building (see the definition of ‘storey’ in Appendix A).

7.7A structure that does not have the minimum fire resistance specified in Appendix B, Table B2, is acceptable if it satisfies all of the following conditions.

a.The structure meets both of the following conditions.

i.It has only one tier.

ii.It is used for storage purposes only.

b.The people likely to be on the floor at any one time are both of the following.

i.Few in number.

ii.Not members of the public.

c.The floor is open above and below to the room or space in which it is situated.

d.The means of escape from the floor is in accordance with Sections 2 to 5.

e.The floor meets both of the following conditions.

i.It is not more than 10m in width or length.

ii.It is a maximum of half the floor area of the space in which it is situated.

The limitations in (e) may be adjusted if any of the following apply.

f.If the lower level has an automatic fire detection and alarm system meeting the recommendations of BS 5839-1, then the floor size may be increased to not more than 20m in either width or length.

g.If agreed with the building control body and the fire and rescue service, then it may be possible to vary this dimension and area. However, the safety of firefighters and the distance they may need to travel over or under the floor must be considered.

h.If the building is fitted throughout with an automatic sprinkler system complying with Appendix E, then no limits are set for the size of the floor.

Source page 77

Provision of compartmentation

All purpose groups

8.1All of the following should be provided as compartment walls and compartment floors and should have, as a minimum, the fire resistance given in Appendix B, Table B1.

8.2A wall common to two or more buildings should be a compartment wall.

8.3Parts of a building occupied mainly for different purposes should be separated from one another by compartment walls and/or compartment floors. Compartmentation is not needed if one of the different purposes is ancillary to the other. See paragraphs 0.23 and 0.24.

8.4Effective compartmentation relies on both of the following.

a.Fire resistance should be continuous at the join between elements forming a compartment.

b.Any openings between two compartments should not reduce the fire resistance.

8.5The lowest floor in a building does not need to be a compartment floor.

Protected shafts

8.6Stairs and service shafts connecting compartments should be protected to restrict the spread of fire between the compartments. These are called protected shafts. Walls or floors surrounding a protected shaft are considered to be compartment walls or compartment floors.

Places of special fire hazard

8.7Fire resisting construction enclosing these places should achieve minimum REI 30. These walls and floors are not compartment walls and compartment floors.

‘Residential (institutional)’ buildings including health care

8.8All floors should be constructed as compartment floors.

8.9Paragraphs 2.35 and 2.36 give guidance on the provisions for compartment walls in care homes that use progressive horizontal evacuation.

‘Residential (other)’ buildings

8.10In ‘residential (other)’ (purpose group (2(b)) buildings, all floors should be compartment floors.

Source page 78

8.11In buildings in a non-residential purpose group (purpose groups 3 to 7), the following should be compartment walls and compartment floors.

a.Every wall needed to divide the building to observe the compartment size limits in Table 8.1 (Diagram 8.1a).

b.Every floor, if the building or separated part of the building (see paragraph 8.19) has a top storey that is more than 30m above ground level (Diagram 8.1b).

c.The floor of the ground storey, if the building has one or more basements (Diagram 8.1c), except in small premises (see paragraph 4.2).

d.The floor of every basement storey (except the lowest floor), if the building or separated part has a basement more than 10m below ground level (Diagram 8.1d).

e.If the building comprises ‘shop and commercial’, ‘industrial’ or ‘storage’ premises (purpose groups 4, 6, 7): every wall or floor dividing a building into separate occupancies (spaces used by different organisations, whether they fall within the same purpose group or not).

f.See also the provision in paragraph 5.46 for store rooms in shops to be separated from retail areas by fire resisting construction (minimum REI 30).

8.12In two storey ‘shop and commercial’ or ‘industrial’ buildings (purpose groups 4 or 6), where the use of the upper storey is ancillary to the use of the ground storey, the ground storey may be treated as a single storey building for fire compartmentation purposes where all of the following apply.

a.The area of the upper storey does not exceed the lower of:

i.20% of the area of the ground storey

ii.500m².

b.The upper storey is compartmented from the lower one.

c.The upper storey has a means of escape independent of the lower storey escape routes.

Every place of special fire hazard (see Appendix E) should be enclosed with fire resisting construction.

Buildings containing one or more atria

8.13Detailed advice on atria in buildings is given in Annexes B and C of BS 9999. For the purposes of this document, BS 9999 applies only where the atrium breaches a compartment.

Source page 79

Source page 80

Source page 81

8.14Buildings within the ‘office’, ‘shop and commercial’, ‘assembly and recreation’, ‘industrial’ and ‘storage’ and other non-residential’ (except car parks for light vehicles) purpose groups (purpose groups 3 to 7(a)) require sprinklers where there is a top storey above 30m. The sprinkler system should be provided in accordance with Appendix E.

Construction of compartment walls and compartment floors

General provisions

8.15All compartment walls and compartment floors should achieve both of the following.

a.Form a complete barrier to fire between the compartments they separate.

b.Have the appropriate fire resistance, as given in Appendix B, Table B1 and Table B2.

8.16Timber beams, joists, purlins and rafters may be built into or carried through a masonry or concrete compartment wall if the openings for them are both of the following.

a.As small as practicable.

b.Fire-stopped.

If trussed rafters bridge the wall, failure of the truss due to a fire in one compartment should not cause failure of the truss in another compartment.

8.17Where services could provide a source of ignition, the risk of fire developing and spreading into adjacent compartments should be controlled.

Compartment walls between buildings

8.18Adjoining buildings should only be separated by walls, not floors. Compartment walls common to two or more buildings should comply with both of the following.

a.Run the full height of the building in a continuous vertical plane.

b.Be continued through any roof space to the underside of the roof.

Separated parts of buildings

8.19Compartment walls forming a separated part of a building should run the full height of the building in a continuous vertical plane.

Separated parts can be assessed independently to determine the appropriate standard of fire resistance in each. The two separated parts can have different standards of fire resistance.

Other compartment walls

8.20Compartment walls not described in paragraphs 8.18 and 8.19 should run the full height of the storey in which they are situated.

8.21Compartment walls in a top storey beneath a roof should be continued through the roof space.

Junction of compartment wall or compartment floor with other walls

8.22At the junction with another compartment wall or an external wall, the fire resistance of the compartmentation should be maintained. Fire-stopping that meets the provisions in paragraphs 10.24 to 10.29 should be provided.

Source page 82

8.23At the junction of a compartment floor and an external wall with no fire resistance, the external wall should be restrained at floor level. The restraint should reduce movement of the wall away from the floor if exposed to fire.

8.24Compartment walls should be able to accommodate deflection of the floor, when exposed to fire, by either of the following means.

a.Between the wall and floor, provide a head detail that is capable of maintaining its integrity while deforming.

b.Design the wall so it maintains its integrity by resisting the additional vertical load from the floor above.

Where compartment walls are located within the middle half of a floor between vertical supports, the deflection may be assumed to be 40mm unless a smaller value can be justified by assessment. Outside this area, the limit can be reduced linearly to zero at the supports.

For steel beams that do not have the required fire resistance, reference should be made to SCI Publication P288.

Junction of compartment wall with roof

8.25A compartment wall should achieve both of the following.

a.Meet the underside of the roof covering or deck, with fire-stopping to maintain the continuity of fire resistance.

b.Be continued across any eaves.

8.26To reduce the risk of fire spreading over the roof from one compartment to another, a 1500mm wide zone of the roof, either side of the wall, should have a covering classified as B_ROOF(t4), on a substrate or deck of a material rated class A2-s3, d2 or better, as set out in Diagram 8.2a.

Thermoplastic rooflights that, because of paragraph 14.7, are regarded as having a BROOF(t4) classification are not suitable_ for use in that zone.

8.27Materials achieving class B-s3, d2 or worse used as a substrate to the roof covering and any timber tiling battens, fully bedded in mortar or other suitable material for the width of the wall (Diagram 8.2b), may extend over the compartment wall in buildings that are both of the following.

a.A maximum of 15m high.

b.In one of the following purpose groups.

i.All residential purpose groups (purpose groups 1 and 2) other than ‘residential (institutional)’ (purpose group 2(a)).

ii.‘Office’ (purpose group 3).

iii.‘Assembly and recreation’ (purpose group 5).

8.28Double-skinned insulated roof sheeting should incorporate a band of material rated class A2-s3, d2 or better, a minimum of 300mm in width, centred over the wall.

8.29As an alternative to the provisions of paragraph 8.26 or 8.27, the compartment wall may extend through the roof for a minimum of either of the following (see Diagram 8.2c).

a.Where the height difference between the two roofs is less than 375mm, 375mm above the top surface of the adjoining roof covering.

b.200mm above the top surface of the adjoining roof covering where either of the following applies.

i.The height difference between the two roofs is 375mm or more.

ii.The roof coverings either side of the wall are of a material classified as B_ROOF(t4).

Source page 83

Source page 84

Openings in compartment walls separating buildings or occupancies

8.30Openings in a compartment wall common to two or more buildings, or between different occupancies in the same building, should be limited to those for either of the following.

a.A fire doorset providing a means of escape, which has the same fire resistance as the wall and is fitted in accordance with the provisions in Appendix C.

b.The passage of a pipe that complies with the provisions in Section 10.

Openings in other compartment walls or in compartment floors

8.31Openings should be limited to those for any of the following.

a.Fire doorsets fitted in accordance with the provisions in Appendix C.

b.Pipes, ventilation ducts, service cables, chimneys, appliance ventilation ducts or ducts encasing one or more flue pipes, complying with the provisions in Section 10.

c.Refuse chutes of class A1 construction.

d.Atria designed in accordance with Annexes B and C of BS 9999.

e.Protected shafts that conform to the provisions in the following paragraphs.

Protected shafts

8.32Any stair or other shaft passing directly from one compartment to another should be enclosed in a protected shaft. Protected shafts should be used for the following only, but may also include sanitary accommodation and washrooms.

a.Stairs.

b.Lifts.

c.Escalators.

d.Chutes.

e.Ducts.

f.Pipes.

g.Additional provisions apply for both of the following.

i.Protected shafts that are protected stairways: Sections 2 to 5.

ii.Stairs that are also firefighting stairs: Section 17.

Construction of protected shafts

8.33The construction enclosing a protected shaft (Diagram 8.3) should do all of the following.

a.Form a complete barrier to fire between the compartments connected by the shaft.

b.Have the appropriate fire resistance given in Appendix B, Table B1, except for uninsulated glazed screens that meet the provisions of paragraph 8.34.

c.Satisfy the provisions for ventilation and the treatment of openings in paragraphs 8.38 and 8.39.

Source page 85

Uninsulated glazed screens to protected shafts

8.34An uninsulated glazed screen may be incorporated in the enclosure to a protected shaft between a stair and a lobby or corridor entered from the stair. The enclosure must conform to Diagram 8.4 and meet all of the following conditions.

a.The standard of fire resistance required for the protected stairway is not more than REI 60.

b.The glazed screen complies with the following.

i.It achieves a minimum rating of E 30.

ii.It complies with the guidance on limits on areas of uninsulated glazing in Appendix B, Table B3.

c.The lobby or corridor is enclosed with fire resisting construction achieving a minimum rating of REI 30.

8.35Where the measures in Diagram 8.4 are not provided, then both of the following apply.

a.The enclosing walls should comply with Appendix B, Table B1.

b.The doors should comply with Appendix B, Table B3.

Source page 86

Pipes for oil or gas and ventilation ducts in protected shafts

8.36A protected shaft containing a protected stairway and/or a lift should not also contain either of the following.

a.A pipe that conveys oil, other than in the mechanism of a hydraulic lift.

b.A ventilating duct. Two exceptions are as follows.

i.A duct provided for pressurising the protected stairway to keep it smoke free.

ii.A duct provided only to ventilate the protected stairway.

A pipe that is completely separated from a protected shaft by fire resisting construction is not considered to be contained within that shaft.

8.37In a protected shaft, any pipe carrying natural gas or LPG should be both of the following.

a.Of screwed steel or all-welded steel construction.

b.Installed in accordance with both of the following.

i.The Pipelines Safety Regulations 1996.

ii.The Gas Safety (Installation and Use) Regulations 1998.

Source page 87

8.38A protected shaft conveying piped flammable gas should be ventilated direct to the outside air, by ventilation openings at high and low level in the shaft.

Any extension of the storey floor into the protected shaft should not compromise the free movement of air throughout the entire length of the shaft.

Guidance on shafts conveying piped flammable gas, including the size of ventilation openings, is given in BS 8313.

Openings into protected shafts

8.39The external wall of a protected shaft does not normally need to have fire resistance. Situations where there are provisions are given in paragraph 3.29 (external walls of protected stairways, which may also be protected shafts) and paragraph 17.2 (firefighting shafts).

Openings in other parts of the enclosure to a protected shaft should be limited to the following.

a.If a wall common to two or more buildings forms part of the enclosure, only the following openings should be made in that wall.

i.A fire doorset providing a means of escape, which has the same fire resistance as the wall and is fitted in accordance with the provisions in Appendix C.

ii.The passage of a pipe that meets the provisions in Section 10.

b.Other parts of the enclosure (other than an external wall) should only have openings for any of the following.

i.Fire doorsets of the appropriate fire resistance, fitted in accordance with the provisions in Appendix C.

ii.The passage of pipes which meet the provisions in Section 10.

iii.Inlets to, outlets from and openings for a ventilation duct (if the shaft contains or serves as a ventilating duct), meeting the provisions in Section 10.

iv.The passage of lift cables into a lift machine room (if the shaft contains a lift). If the machine room is at the bottom of the shaft, the openings should be as small as practicable.

Source page 88

9.1Cavities in the construction of a building provide a ready route for the spread of smoke and flame, which can present a greater danger as any spread is concealed. For the purpose of this document, a cavity is considered to be any concealed space.

Source page 89

9.2To reduce the potential for fire spread, cavity barriers should be provided for both of the following.

a.To divide cavities.

b.To close the edges of cavities.

See Diagram 9.1. Cavity barriers should not be confused with fire-stopping details (Section 10).

Pathways around fire-separating elements

Junctions and edges of cavities

9.3Cavity barriers should be provided at all of the following locations.

a.At the edges of cavities, including around openings (such as windows, doors and exit/entry points for services).

b.At the junction between an external cavity wall and every compartment floor and compartment wall.

c.At the junction between an internal cavity wall and every compartment floor, compartment wall or other wall or door assembly forming a fire resisting barrier.

This does not apply where a wall meets the conditions of Diagram 9.2.

9.4It is not appropriate to complete a line of compartment walls by fitting cavity barriers above them. The compartment wall should extend to the underside of the floor or roof above.

Protected escape routes

9.5If the fire resisting construction of a protected escape route is either of the following.

a.Not carried to full storey height.

b.At the top storey, not carried to the underside of the roof covering.

Then the cavity above or below the fire resisting construction should be either of the following.

i.Fitted with cavity barriers on the line of the enclosure.

ii.For cavities above the fire resisting construction, enclosed on the lower side by a fire resisting ceiling (minimum EI 30) that extends throughout the building, compartment or separated part (see Diagram 9.3).

Cavities affecting alternative escape routes

9.6In divided corridors, cavity barriers may be needed to prevent alternative escape routes being affected by fire and/or smoke (see paragraph 2.27 and Diagram 2.9).

Separation of bedrooms in ‘residential (institutional)’ and ‘residential (other)’ buildings

9.7Where a cavity exists above or below a partition between bedrooms because the enclosure is not carried to full storey height or to the underside of the roof covering, the guidance in paragraph 9.5 should be followed.

Source page 90

9.8Cavity barriers are not required between double-skinned corrugated or profiled insulated roof sheeting if the sheeting complies with all of the following.

a.The sheeting is rated class A2-s3, d2 or better.

b.Both surfaces of the insulating layer are rated class C-s3, d2 or better.

c.Both surfaces of the insulating layer make contact with the inner and outer skins of cladding (Diagram 9.4).

Source page 91

Extensive cavities

Maximum dimensions of cavities

9.9Cavity barriers should be used to divide any cavity (including roof spaces). Table 9.1 sets out maximum dimensions for undivided cavities.

9.10Table 9.1 does not apply to any of the following cavities.

a.A cavity in a wall that is fire resisting only because it is loadbearing.

b.A cavity in a wall that meets the conditions of Diagram 9.2.

c.A floor or roof cavity above a fire resisting ceiling (Diagram 9.3) that extends throughout the building or compartment to a maximum of 30m.

d.In a building not put to residential or institutional use, a cavity that does not contain materials achieving class B-s3, d2 or worse and is formed either:

i.behind the external skin of an external cladding system with a masonry or concrete inner leaf a minimum of 75mm thick

ii.by overcladding an existing masonry (or concrete) external wall or an existing concrete roof.

e.A cavity that meets the conditions of paragraph 9.8.

f.A cavity below a floor next to the ground or next to oversite concrete, if either:

Source page 92

i.the cavity is less than 1000mm in height

ii.the cavity is not normally accessible by people, unless there are openings in the floor such that it is possible for materials to accumulate in the cavity (in which case cavity barriers should be provided and access should be provided to the cavity for cleaning).

9.11If a single room with a ceiling cavity or underfloor cavity exceeds the dimensions in Table 9.1, cavity barriers need only be provided on the line of the enclosing walls/partitions of that room, if both of the following apply.

a.The cavity barriers are a maximum of 40m apart.

b.The surface of the material/product exposed in the cavity is class C-s3, d2 or better.

9.12If the cavity is over an undivided area that exceeds 40m in any direction, there is no limit to its size if all of the following conditions are met.

a.Together, the room and cavity form a compartment separated from the rest of the building.

b.Both of the following apply.

i.The building is fitted with an automatic fire detection and alarm system that conforms to BS 5839-1.

ii.Detectors are only required in the cavity to satisfy BS 5839-1.

c.If the cavity is used as a plenum then the recommendations for recirculating air distribution systems in Section 32 of BS 9999 are followed.

d.Both of the following apply.

i.The exposed surface of the material/product used in the construction of the cavity is class B-s3, d2 or better.

ii.The supports and fixings in the cavity are class A1.

e.Any pipe insulation system should achieve class C-s3, d2 rating or better.

f.Any electrical wiring in the cavity is laid in metal trays or metal conduit.

g.Other than those in (d)–(f), any materials are class A2-s3, d2 rated or better.

Construction and fixings for cavity barriers

9.13Cavity barriers, tested from each side separately, should provide a minimum of both of the following:

a.30 minutes’ integrity (E 30)

b.15 minutes’ insulation (I 15).

They may be formed by a construction provided for another purpose if it achieves the same performance.

9.14Cavity barriers in a stud wall or partition, or provided around openings, may be formed of any of the following.

a.Steel, a minimum of 0.5mm thick.

b.Timber, a minimum of 38mm thick.

c.Polythene-sleeved mineral wool, or mineral wool slab, under compression when installed in the cavity.

Source page 93

d.Calcium silicate, cement-based or gypsum-based boards, a minimum of 12mm thick.

These do not necessarily achieve the performance specified in paragraph 9.13.

9.15Cavity barriers should be tightly fitted to a rigid construction and mechanically fixed in position. If this is not possible (e.g. where a cavity barrier joins to slates, tiles, corrugated sheeting or similar materials) the junction should be fire-stopped.

9.16Cavity barriers should be fixed so their performance is unlikely to be made ineffective by any of the following.

a.Movement of the building due to subsidence, shrinkage or temperature change, and movement of the external envelope due to wind.

b.During a fire, collapse of services penetrating the cavity barriers, either by the failure of the supporting system or through degradation of the service itself (e.g. by melting or burning).

c.During a fire, failure of the cavity barrier fixings. (In roof spaces, where cavity barriers are fixed to roof members, there is no expectation of fire resistance from roof members provided for the purpose of support.)

d.During a fire, failure of any material or construction to which cavity barriers abut. (For example, a suspended ceiling that continues over a fire resisting wall or partition collapses, and the cavity barrier fails prematurely because the ceiling was not designed to provide a minimum fire resistance of EI 30.)

Openings in cavity barriers

9.17Openings should be limited to the following.

a.Fire doorsets with a minimum rating of E 30, fitted in accordance with Appendix C.

b.The passage of pipes that follow the provisions in Section 10.

c.The passage of cables or conduits containing one or more cables.

d.Openings fitted with a suitably mounted and appropriate fire damper.

e.Ducts that are either of the following.

i.Fire resisting (minimum E 30).

ii.Fitted with a suitably mounted and appropriate fire damper where they pass through the cavity barrier.

9.18If a cavity barrier is provided above or below a partition between bedrooms in ‘residential (institutional)’ and ‘residential (other)’ (purpose groups 2(a) and 2(b)) buildings, and the partition is not a fire resisting partition, then paragraph 9.17 does not apply. However, both of the following apply.

a.The number of openings in the barrier should be kept to a minimum.

b.Any penetrations should be sealed to restrict the passage of smoke with an appropriate fire-stopping material.

Source page 94

Introduction

10.1Every joint, imperfect fit and opening for services through a fire-separating element should be sealed with fire-stopping to ensure the fire resistance of the element is not impaired. Fire-stopping delays the spread of fire and, generally, the spread of smoke as well.

Openings for pipes

10.2Pipes passing through a fire-separating element, unless in a protected shaft, should comply with one of the alternatives A, B or C below.

Alternative A: Proprietary seals (any pipe diameter)

10.3Provide a proprietary, tested sealing system that will maintain the fire resistance of the wall, floor or cavity barrier.

Alternative B: Pipes with a restricted diameter

10.4Where a proprietary sealing system is not used, fire-stop around the pipe, keeping the opening for the pipe as small as possible. The nominal internal diameter of the pipe should not exceed the relevant dimension given in Table 10.1.

Alternative C: Sleeving

10.5A pipe with a maximum nominal internal diameter of 160mm may be used with a sleeve made out of a high melting point metal, as shown in Diagram 10.1, if the pipe is made of one of the following.

a.Lead.

b.Aluminium.

c.Aluminium alloy.

d.Fibre-cement.

e.uPVC (pipes should also comply with either BS 4514 or BS 5255).

A high melting point metal means any metal (such as cast iron, copper or steel) which, if exposed to a temperature of 800°C, will not soften or fracture to the extent that flame or hot gas will pass through the wall of the pipe.

Source page 95

Mechanical ventilation and air-conditioning systems

General provisions

10.6Ductwork should not help to transfer fire and smoke through the building. Terminals of exhaust points should be sited away from final exits, cladding or roofing materials achieving class B-s3, d2 or worse and openings into the building.

10.7Ventilation ducts supplying or extracting air directly to or from a protected stairway should not also serve other areas. A separate ventilation system should be provided for each protected stairway.

10.8A fire and smoke damper should be provided where ductwork enters or leaves each section of the protected escape route it serves. It should be operated by a smoke detector or suitable fire detection system. Fire and smoke dampers should close when smoke is detected. Alternatively, the methods set out in paragraphs 10.15 and 10.16 and Diagrams 10.2 and 10.3 may be followed.

Source page 96

10.9In a system that recirculates air, smoke detectors should be fitted in the extract ductwork before both of the following.

a.The point where recirculated air is separated from air to be discharged to the outside.

b.Any filters or other air cleaning equipment.

When smoke is detected, detectors should do one of the following.

a.Cause the system to immediately shut down.

b.Switch the ventilation system from recirculating mode to extraction to divert smoke outside the building.

10.10Non-domestic kitchens, car parks and plant rooms should have separate and independent extraction systems. Extracted air should not be recirculated.

10.11Under fire conditions, ventilation and air-conditioning systems should be compatible with smoke control systems and need to be considered in their respective design.

Ventilation ducts and flues passing through fire-separating elements

General provisions

10.12If air handling ducts pass through fire-separating elements, the fire performance of the elements should be maintained using one or more of the following four methods. In most ductwork systems, a combination of the four methods is best.

a.Method 1 – thermally activated fire dampers.

b.Method 2 – fire resisting enclosures.

c.Method 3 – protection using fire resisting ductwork.

d.Method 4 – automatically activated fire and smoke dampers triggered by smoke detectors.

10.13Further information on fire resisting ductwork is given in the ASFP Blue Book.

Kitchen extract

10.14Methods 1 and 4 should not be used for extract ductwork serving kitchens. The likely build-up of grease within the duct can adversely affect dampers.

Ducts passing through protected escape routes

10.15Method 1 should not be used for extract ductwork passing through the enclosures of protected escape routes (Diagrams 10.2 and 10.3), as large volumes of smoke can pass thermal devices without triggering them.

10.16An ES classified fire and smoke damper which is activated by a suitable fire detection system (method 4) may also be used for protected escape routes.

Source page 97

Source page 98

10.17Both fire dampers and fire and smoke dampers should be all of the following.

a.Sited within the thickness of the fire-separating elements.

b.Securely fixed.

c.Sited such that, in a fire, expansion of the ductwork would not push the fire damper through the structure.

10.18Access to the fire damper and its actuating mechanism should be provided for inspection, testing and maintenance.

10.19Fire dampers should meet both of the following conditions.

a.Conform to BS EN 15650.

b.Have a minimum E classification of 60 minutes or to match the integrity rating of the fire resisting elements, whichever is higher.

10.20Fire and smoke dampers should meet both of the following conditions.

a.Conform to BS EN 15650.

b.Have a minimum ES classification of 60 minutes or to match the integrity rating of the fire resisting elements, whichever is higher.

10.21Smoke detectors should be sited so as to prevent the spread of smoke as early as practicable by activating the fire and smoke dampers. Smoke detectors and automatic release mechanisms used to activate fire dampers and/or fire and smoke dampers should conform to BS EN 54-7 and BS 5839-3 respectively.

Further information on fire dampers and/or fire and smoke dampers is given in the ASFP Grey Book.

Sleeping risks

10.22Where the use of the building involves a sleeping risk, fire dampers or fire and smoke dampers should be actuated by both of the following.

a.Smoke detector-controlled automatic release mechanisms.

b.Thermally actuated devices.

However, in a situation where both of the following are true:

a.all occupants of the building can be expected to make an unaided escape

b.an L1 fire detection and alarm system is installed in accordance with BS 5839-1

then both of the following exceptions may be made.

i.If, on the detection of smoke, the fire alarm system signals the immediate evacuation of all the occupants of the building, then fire dampers and/or fire and smoke dampers do not need to be actuated by smoke detectors.

ii.If the building is divided into fire compartments and the alarm system is arranged to signal the immediate evacuation of the occupants of the fire compartment in which the fire has been detected, then smoke detector-operated fire dampers or fire and smoke dampers need only be provided where ductwork enters or leaves the fire compartment.

Source page 99

10.23The wall of a flue, duct containing flues or appliance ventilation duct(s) should have a fire resistance (REI) that is at least half of any compartment wall or compartment floor it passes through or is built into (Diagram 10.4).

Fire-stopping

10.24In addition to any other provisions in this section, both of the following conditions should be met.

a.Joints between fire-separating elements should be fire-stopped.

b.Openings through a fire resisting element for pipes, ducts, conduits or cable should be all of the following.

i.As few as possible.

ii.As small as practicable.

iii.Fire-stopped (allowing thermal movement in the case of a pipe or duct).

10.25Materials used for fire-stopping should be reinforced with (or supported by) materials rated class A2-s3, d2 or better to prevent displacement in both of the following cases.

a.Where the unsupported span is greater than 100mm.

b.Where non-rigid materials are used (unless subjected to appropriate fire resistance testing to show their suitability).

10.26Proprietary, tested fire-stopping and sealing systems are available and may be used. Different materials suit different situations and not all are suitable in every situation.

Source page 100

10.27Other fire-stopping materials include the following.

a.Cement mortar.

b.Gypsum-based plaster.

c.Cement-based or gypsum-based vermiculite/perlite mixes.

d.Glass fibre, crushed rock, blast furnace slag or ceramic-based products (with or without resin binders).

e.Intumescent mastics.

These may be used in situations appropriate to the particular material. Not all materials will be suitable in every situation.

10.28Guidance on the design, installation and maintenance of measures to contain fires or slow their spread is given in Ensuring Best Practice for Passive Fire Protection in Buildings produced by the Association for Specialist Fire Protection (ASFP).

10.29Further information on generic systems, their suitability for different applications and guidance on test methods is given in the ASFP Red Book.

Source page 101

11.1Car parks call for different measures to restrict fire spread within buildings for the following reasons.

a.The fire load is well defined.

b.The probability of fire spreading from one storey to another in a well ventilated car park is low. Guidance is therefore given for three ventilation scenarios.

Open-sided car parks

Natural ventilation

11.2For the purposes of assessing fire resistance, a building, compartment or separated part containing a car park may be regarded as open-sided when it complies with all of the following.

a.There are no basement storeys.

b.Each storey is naturally ventilated by permanent openings at each car parking level. The aggregate vent area is a minimum of 1/20 of that level’s floor area, at least half of which is provided equally by two opposite walls (1/80 on each side). The remaining free area can be distributed wherever possible.

c.Where one element of structure supports, carries or stabilises another, the fire resistance of the supporting element at least matches the minimum period of fire resistance for the other element.

d.In mixed use buildings, the fire resistance of any element that supports, carries or stabilises an element in the other part of the building should at least match the minimum period of fire resistance for the other element.

e.All materials used in the construction should be class A1 rated, except for the following.

i.Any surface finish applied to a floor or roof of the car park (or within any building, compartment or separated part adjoining the structure enclosing it), if the finish meets requirements B2 and B4.

ii.Any fire doorset.

iii.Any attendant’s kiosk not exceeding 15m² in area.

iv.Any shop mobility facility.

Car parks that are not open-sided

11.3For car parks that do not have the ventilation set out in paragraph 11.2, the required fire resistance is given in Appendix B, Table B2. Ventilation should be either natural or mechanical. See Approved Document F for additional guidance on ventilation of car parks.

Natural ventilation

11.4Each storey should be ventilated by permanent openings at each car parking level. The openings can be at ceiling level. The aggregate free vent area should be a minimum of 1/40 of that level’s floor area, at least half of which should be provided equally by two opposite walls (1/160 on each side). The remaining free area can be distributed wherever possible.

Source page 102

11.5If the minimum standard of natural ventilation is not possible, a system of mechanical ventilation should be provided that complies with all of the following.

a.The system should be both of the following.

i.Independent of any other ventilating system (other than any system that provides day to day ventilation to the car park).

ii.Designed to operate at 10 air changes per hour during a fire.

b.The system should run in two parts, each of which is:

i.capable of extracting 50% of the rates set out in item (a)

ii.able to operate alone or with the other part

iii.provided with an independent power supply capable of operating if the main supply fails.

c.50% of the outlets should be at high level and 50% at low level.

d.The system should use E, I and S ductwork in accordance with BS EN 1366-8.

For further information on equipment for removing hot smoke, refer to BS EN 12101-3. An alternative method of providing smoke ventilation from enclosed car parks is given in BS 7346-7.

Source page 103

These sections deal with the following requirement from Part B of Schedule 1 to the Building Regulations 2010. Section 12 also refers to regulation 7(2) of the Building Regulations 2010. Guidance on regulation 7(1) can be found in Approved Document 7.

Regulation 7 – Materials and workmanship

(1)Building work shall be carried out—

(a)with adequate and proper materials which—

(i)are appropriate for the circumstances in which they are used,

(ii)are adequately mixed or prepared, and

(iii)are applied, used or fixed so as adequately to perform the functions for which they are designed; and

(b)in a workmanlike manner.

(1A)Building work shall be carried out so that relevant metal composite material does not become part of an external wall, or specified attachment, of any building.

(2)Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1 (classified in accordance with the reaction to fire classification).

Source page 104

(3)Paragraph (2) does not apply to—

(a)cavity trays when used between two leaves of masonry;

(b)any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6)) if that part is connected to an external wall;

(c)door frames and doors;

(d)electrical installations;

(da)fibre optic cables;

(e)insulation and water proofing materials used below ground level or up to 300mm above that level;

(f)intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;

(g)membranes;

(h)seals, gaskets, fixings, sealants and backer rods;

(ha)components associated with a solar shading device, excluding components whose primary function is to provide shade or deflect sunlight, such as the awning curtain or slats;

(i)thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1;

(j)window frames and glass; or

(k)materials which form the top horizontal floor layer of a balcony which are of European Classification A1fl or A2fl-s1 (classified in accordance with the reaction to fire classification) provided that the entire layer has an imperforate substrate under it.

(4)In this regulation—

(a)a “relevant building” means a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and which—

(i)contains one or more dwellings;

(ii)contains an institution; or

(iii)contains a room for residential purposes; and

(b)“above ground level” in relation to a storey means above ground level when measured from the lowest ground level adjoining the outside of a building to the top of the floor surface of the storey.

Source page 105

Resisting fire spread over external walls

The external envelope of a building should not contribute to undue fire spread from one part of a building to another part. This intention can be met by constructing external walls so that both of the following are satisfied.

a.The risk of ignition by an external source to the outside surface of the building and spread of fire over the outside surface is restricted.

b.The materials used to construct external walls, and attachments to them, and how they are assembled do not contribute to the rate of fire spread up the outside of the building.

The extent to which this is necessary depends on the height and use of the building.

Resisting fire spread from one building to another

The external envelope of a building should not provide a medium for undue fire spread to adjacent buildings or be readily ignited by fires in adjacent buildings. This intention can be met by constructing external walls so that all of the following are satisfied.

a.The risk of ignition by an external source to the outside surface of the building is restricted.

b.The amount of thermal radiation that falls on a neighbouring building from window openings and other unprotected areas in the building on fire is not enough to start a fire in the other building.

c.Flame spread over the roof and/or fire penetration from external sources through the roof is restricted.

The extent to which this is necessary depends on the use of the building and its position in relation to adjacent buildings and therefore the site boundary.

Source page 106

Introduction

12.1The external wall of a building should not provide a medium for fire spread if that is likely to be a risk to health and safety. Combustible materials and cavities in external walls and attachments to them can present such a risk, particularly in tall buildings. The guidance in this section is designed to reduce the risk of fire spread as well as the risk of ignition from flames coming from adjacent buildings.

Fire resistance

12.2This section provides guidance on resisting fire spread over external walls; however, it does not deal with fire resistance of external walls. An external wall may need fire resistance to meet the provisions of Section 2 (Design for horizontal escape), Section 3 (Design for vertical escape), Section 7 (Loadbearing elements of structure), Section 13 (Resisting fire spread from one building to another) or Section 17 (Access to buildings for firefighting personnel).

Combustibility of external walls

12.3The external walls of buildings other than those described in regulation 7(4) of the Building Regulations should achieve either of the following.

a.Follow the provisions given in paragraphs 12.5 to 12.10, which provide guidance on all of the following.

i.External surfaces.

ii.Materials and products.

iii.Cavities and cavity barriers.

b.Meet the performance criteria given in BRE report BR 135 for external walls using full-scale test data from BS 8414-1 or BS 8414-2.

12.4In relation to buildings of any height or use, consideration should be given to the choice of materials (including their extent and arrangement) used for the external wall, or attachments to the wall (e.g. balconies, etc.), to reduce the risk of fire spread over the wall.

External surfaces

12.5The external surfaces (i.e. outermost external material) of external walls should comply with the provisions in Table 12.1. The provisions in Table 12.1 apply to each wall individually in relation to its proximity to the relevant boundary.

Source page 107

Source page 108

12.6In a building with a storey 18m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s3, d2 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 9.2 in Section 9. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.

12.7In buildings that include a ‘residential’ purpose (purpose groups 1 and 2) with a storey 11m or more in height (see Diagram D6 in Appendix D) any insulation product, filler material (such as the core materials of metal composite panels, sandwich panels and window spandrel panels but not including gaskets, sealants and similar) etc. used in the construction of an external wall should be class A2-s1, d0 or better (see Appendix B). This restriction does not apply to masonry cavity wall construction which complies with Diagram 9.2 in Section 9. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.

12.8Best practice guidance for green walls (also called living walls) can be found in Fire Performance of Green Roofs and Walls, published by the Department for Communities and Local Government. Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.

Cavities and cavity barriers

12.9Cavity barriers should be provided in accordance with Section 9.

12.10In the case of an external wall construction of a building which, by virtue of paragraph 9.10d (external cladding system with a masonry or concrete inner leaf), is not subject to the provisions of Table 9.1, the surfaces which face into cavities should also meet the provisions of Table 12.1 and provisions in Section 9, but where regulation 7(2) applies, that regulation prevails over the guidance provided in Table 12.1 and Section 9.

Balconies

12.11In buildings that include a ‘residential’ purpose (purpose groups 1 and 2) with a storey 11m or more in height (see Diagram D6 in Appendix D) balconies should meet either of the following conditions.

a.Only contain materials achieving class A1 or A2-s1, d0, except for any of the following.

i.Cavity trays when used between two leaves of masonry.

ii.Intumescent and fire-stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1 to the Building Regulations 2010.

iii.Membranes.

iv.Seals, gaskets, fixings, sealants and backer rods.

v.Thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1 to the Building Regulations 2010.

vi.Any material achieving class A1fl or A2fl-s1 when it forms the top horizontal floor layer of a balcony and is provided with an imperforate substrate under it which extends to the full size of the class A1fl or A2fl-s1 material.

vii.Electrical installations.

viii.Fibre optic cables.

Source page 109

b.Achieve both of the following conditions.

i.Have an imperforate soffit which extends to the full area of the balcony, achieves a minimum REI 30 rating and is constructed of materials achieving class A2-s1, d0 or better.

ii.Materials achieving class B-s1, d0 or worse extending beyond the boundary of a single compartment should include a band of material rated class A2-s1, d0 or better, a minimum of 300mm in width centred on that boundary line.

Where regulation 7(2) applies, that regulation prevails over all the provisions in this paragraph.

Metal composite materials

12.12Regulation 7(1A) prohibits the use of relevant metal composite materials in the external walls, and specified attachments, of all buildings of any height.

12.13Relevant metal composite materials are defined (in regulation 2(6)(c)) as any panel or sheet, having a thickness of no more than 10mm which is composed of a number of layers two or more of which are made of metal, alloy or metal compound and one or more of which is a substantial layer made of a material having a gross calorific value of more than 35MJ/kg when tested in accordance with BS EN ISO 1716. A substantial layer is defined as a layer which is at least 1mm thick or has a mass per unit area of at least 1kg/m².

Regulation 7(2) and requirement B4

Materials

12.14Regulation 7(1)(a) requires that materials used in building work are appropriate for the circumstances in which they are used. Regulation 7(2) sets requirements in respect of external walls and specified attachments in relevant buildings.

12.15Regulation 7(2) applies to any building with a storey at least 18m above ground level (as measured in accordance with Diagram D6 in Appendix D) and which contains one or more dwellings; an institution; or a room for residential purposes. It requires that all materials which become part of an external wall or specified attachment achieve class A2-s1, d0 or class A1 in accordance with BS EN 13501-1, other than those exempted by regulation 7(3).

12.16External walls and specified attachments are defined in regulation 2(6) and these definitions include any parts of the external wall as well as balconies, solar panels and solar shading.

12.17Regulation 7(3) provides an exemption for certain components found in external walls and specified attachments.

Source page 110

12.18Regulations 5(k) and 6(3) provide that, where the use of a building is changed such that the building becomes a building described in regulation 7(4), the construction of the external walls, and specified attachments, must be investigated and, where necessary, work must be carried out to ensure they only contain materials achieving class A2-s1, d0 or class A1, other than those exempted by regulation 7(3).

Solar shading devices

12.19Regulation 7(2) requires that the curtain and or slats of solar shading devices in a relevant building (as defined in regulation 7(4)) achieve class A1 or A2-s1, d0. The curtain of solar shading devices cannot be classified as a membrane in accordance with regulation 7(3).

12.20Solar shading devices installed up to 4.5m above ground level are not required to meet the requirements of regulation 7(2).

Additional considerations

12.21The provisions of regulation 7 apply in addition to requirement B4. Therefore, for buildings described in regulation 7(4), the potential impact of any products incorporated into or onto the external walls and specified attachments should be carefully considered with regard to their number, size, orientation and position.

12.22Particular attention is drawn to the following points.

a.Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0. Roofing membranes do not need to achieve a minimum of class A2-s1, d0 when used as part of a roof connecting to an external wall.

b.Internal linings should comply with the guidance provided in Section 4.

c.Any part of a roof should achieve the minimum performance as detailed in Section 12.

d.As per regulation 7(3), window frames and glass (including laminated glass) are exempted from regulation 7(2). Window spandrel panels and infill panels must comply with regulation 7(2).

e.Thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break).

f.Regulation 7(2) only applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 7(2), although attention is drawn to paragraph 12.22g.

g.While regulation 7(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.

h.Any material achieving class A1fl or A2fl-s1 in accordance with BS EN 13501-1 is exempted when it meets both of the following conditions.

i.It forms the top horizontal floor layer of a balcony.

ii.It is provided with an imperforate substrate under it which extends to the full size of the class A1fl or A2fl-s1 material.

Source page 111

Introduction

13.1The following assumptions enable a reasonable standard of resistance to the spread of fire to be specified.

a.The size of a fire depends on the compartmentation within the building. A fire may involve a complete compartment, but will not spread to other compartments.

b.The intensity of fire is related to the building use, but can be moderated by a sprinkler system.

c.Fires in ‘residential’ and ‘assembly and recreation’ buildings (purposes groups 1, 2 and 5) represent a greater risk to life.

d.A building on the far side of the relevant boundary meets both of the following conditions.

i.Has a similar elevation to the one in question.

ii.Is at the same distance from the common boundary.

e.The radiated heat passing through any part of the fire resisting external wall may be discounted.

13.2Where regulation 7(2) applies, that regulation prevails over the provisions within this section.

13.3If a reduced separation distance between buildings, or increased amount of unprotected area, is required, smaller compartments should be considered.

Boundaries

13.4The fire resistance of a wall depends on its distance from the relevant boundary (see Diagram 13.1). Separation distances are measured to boundaries to ensure that the location and design of buildings on adjoining sites have no influence on the building under consideration.

13.5The boundary that a wall faces is the relevant boundary (Diagram 13.2). It may be one of the following.

a.The site boundary.

b.The centre line of a space where further development is unlikely, such as a road, railway, canal or river.

c.An assumed notional boundary between two buildings on the same site (Diagram 13.3) where either of the following conditions is met.

i.One or both of the buildings are in the ‘residential’ or ‘assembly and recreation’ purpose groups (purpose group 1, 2 or 5).

ii.The buildings will be operated/managed by different organisations.

Source page 112

Source page 113

Source page 114

13.6Parts of an external wall with less fire resistance than the appropriate amount given in Appendix B, Table B2, are called unprotected areas.

13.7Where a fire resisting external wall has an external surface material that is worse than class B-s3, d2 and is more than 1mm thick, that part of the wall should be classified as an unprotected area equating to half its area (Diagram 13.4).

External walls on, and within 1000mm of, the relevant boundary

13.8Unprotected areas should meet the conditions in Diagram 13.5 and the rest of the wall should be fire resisting from both sides.

External surface materials facing the boundary should be class B-s3, d2 or better.

External walls 1000mm or more from the relevant boundary

13.9Unprotected area should not exceed the result given by one of the methods in paragraph 13.17, and the rest of the wall (if any) should be fire resisting but only from the inside of the building.

External walls of protected stairways

13.10Exclude external walls of stairways in a protected shaft when assessing unprotected areas (see Diagram 3.3)

Source page 115

13.11In an otherwise protected wall, small unprotected areas may be ignored where they meet the conditions in Diagram 13.5.

Large uncompartmented buildings

13.12For the purposes of assessing unprotected area, parts of walls of uncompartmented buildings that are more than 30m above mean ground level may be ignored.

Canopies

13.13Where both of the following apply, separation distances may be determined from the wall rather than from the edge of the canopy (Diagram 13.6).

a.The canopy is attached to the side of a building.

b.The edges of the canopy are a minimum of 2m from the relevant boundary.

Canopies that fall within class 6 or class 7 of Schedule 2 to the regulations (Exempt Buildings and Work) are exempt from the Building Regulations.

13.14Space separation may be disregarded if a canopy is all of the following.

a.Free-standing.

b.Above a limited risk or controlled hazard, for example over petrol pumps.

c.A minimum of 1000mm from the relevant boundary.

Source page 116

Roofs

13.15Roofs with a pitch of more than 70 degrees to the horizontal should be assessed in accordance with this section. Vertical parts of a pitched roof, such as dormer windows, should be included, only if the slope of the roof exceeds 70 degrees.

It is a matter of judgement whether a continuous run of dormer windows that occupies most of a steeply pitched roof should be treated as a wall rather than a roof.

Portal frames

13.16Portal frames are often used in single storey industrial and commercial buildings where there may be no need for fire resistance of the structure (requirement B3). However, where a portal framed building is near a relevant boundary, the external wall near the boundary may need fire resistance to restrict the spread of fire between buildings. It is generally accepted that a portal frame acts as a single structural element because of the moment-resisting connections used, especially at the column/rafter joints. Thus, in cases where the external wall of the building cannot be wholly unprotected, the rafter members of the frame, as well as the column members, may need to be fire protected. The design method for this is set out in SCI Publication P313.

Source page 117

Methods for calculating acceptable unprotected area

13.17Two simple methods are given for calculating the acceptable amount of unprotected area in an external wall that is a minimum of 1000mm from any point on the relevant boundary. More precise methods are described in BRE report BR 187 and may be used instead. When using BR 187 the following radiation intensity at each unprotected area should be assumed.

a.84kW/m² if the purpose group of the building is ‘residential’ (purpose groups 1 or 2), ‘office’ (purpose group 3) or ‘assembly and recreation’ (purpose group 5) or if the building is an open-sided multi-storey car park (purpose group 7(b)).

b.168kW/m² if the purpose group of the building is ‘shop and commercial’ (purpose group 4), ‘industrial’ (purpose group 6) or ‘storage and other non-residential’ (purpose group 7(a)).

Method 1

13.18This method applies to small buildings intended to be used for ‘residential (other)’ purposes.

13.19The building should not exceed three storeys in height (excluding basements) or 24m in length. Each side of the building should meet the limits stated in Diagram 13.7. Any small unprotected areas falling within the limits shown in Diagram 13.5 can be ignored.

Source page 118

13.20This method may be used for buildings or compartments intended for any use and for which method 1 is not appropriate.

13.21Except for an open-sided car park in purpose group 7(b) (see paragraph 11.2), the building should not exceed 10m in height. Each side of the building should meet the limits in Table 13.1. Areas falling within the limits in Diagram 13.5 can be ignored.

Sprinkler systems

13.22If a building is fitted throughout with a sprinkler system in accordance with Appendix E, either of the following is permitted.

a.The boundary distance can be halved, to a minimum distance of 1m.

b.The amount of unprotected area can be doubled.

Atrium buildings

13.23If a building contains one or more atria, the recommendations in clause B8 of BS 9999 should be followed.

Source page 119

Introduction

14.1‘Roof covering’ describes one or more layers of material, but not the roof structure as a whole.

14.2Provisions for the fire properties of roofs are given in other parts of this document.

a.Requirement B1 – for roofs that are part of a means of escape.

b.Requirement B2 – for the internal surfaces of rooflights as part of internal linings.

c.Requirement B3 – for roofs that are used as a floor and for roofs passing over a compartment wall.

d.Section 13 – the circumstances in which a roof is subject to the provisions for space separation.

Separation distances

14.3Separation distance is the minimum distance from the roof, or part of the roof, to the relevant boundary (paragraph 13.5). Table 14.1 sets out separation distances by the type of roof covering and the size and use of the building.

In addition, roof covering products (and/or materials) defined in Commission Decision 2000/553/EC of 6 September 2000, implementing Council Directive 89/106/EEC, can be considered to fulfil all of the requirements for the performance characteristic ‘external fire performance’ without the need for testing, provided that any national provisions on the design and execution of works are fulfilled, and can be used without restriction.

14.4The performance of rooflights is specified in a similar way to the performance of roof coverings. Plastic rooflights may also be used.

Plastic rooflights

14.5Table 14.2 and Diagram 14.1 set the limitations for using plastic rooflights whose lower surface has a minimum rating of class D-s3, d2.

14.6Table 14.3 sets the limitations for using thermoplastic materials with a TP(a) rigid or TP(b) (see also Diagram 14.1) classification. The method of classifying thermoplastic materials is given in Appendix B.

14.7Other than for the purposes of Diagram 8.2, polycarbonate or uPVC rooflights achieving a minimum rating of class C-s3, d2 can be regarded as having a B_ROOF(t4) classification.

Unwired glass in rooflights

14.8When used in rooflights, unwired glass a minimum of 4mm thick can be regarded as having a B_ROOF(t4) classification.

Thatch and wood shingles

14.9If the performance of thatch or wood shingles cannot be established, they should be regarded as having an E_ROOF(t4) classification in Table 14.1.

Source page 120

Source page 121

Source page 122

These sections deal with the following requirement from Part B of Schedule 1 to the Building Regulations 2010.

Intention

Provisions covering access and facilities for the fire service are to safeguard the health and safety of people in and around the building. Their extent depends on the size and use of the building. Most firefighting is carried out within the building. In the Secretary of State’s view, requirement B5 is met by achieving all of the following.

a.External access enabling fire appliances to be used near the building.

b.Access into and within the building for firefighting personnel to both:

i.search for and rescue people

ii.fight fire.

c.Provision for internal fire facilities for firefighters to complete their tasks.

d.Ventilation of heat and smoke from a fire in a basement.

If an alternative approach is taken to providing the means of escape, outside the scope of this approved document, additional provisions for firefighting access may be required. Where deviating from the general guidance, it is advisable to seek advice from the fire and rescue service as early as possible (even if there is no statutory duty to consult).

Source page 123

Buildings not fitted with fire mains

15.1For small buildings (up to 2000m², with a top storey that is a maximum of 11m above ground level), vehicle access for a pump appliance should be provided to whichever is the less onerous of the following.

a.15% of the perimeter.

b.Within 45m of every point of the footprint of the building (see Diagram 15.1).

15.2For all other buildings, provide vehicle access in accordance with Table 15.1.

15.3Every elevation to which vehicle access is provided should have a door, a minimum of 750mm wide, to give access into the building. The maximum distance between doors, or between a door and the end of the elevation, is 60m (e.g. a 150m elevation would need a minimum of two doors).

Source page 124

Source page 125

15.4For buildings fitted with dry fire mains, both of the following apply.

a.Access should be provided for a pumping appliance to within 18m of each fire main inlet connection point. Inlets should be on the face of the building.

b.The fire main inlet connection point should be visible from the parking position of the appliance, and satisfy paragraph 16.10.

15.5For buildings fitted with wet fire mains, access for a pumping appliance should comply with both of the following.

a.Within 18m, and within sight of, an entrance giving access to the fire main.

b.Within sight of the inlet to replenish the suction tank for the fire main in an emergency.

15.6Where fire mains are provided in buildings for which Sections 16 and 17 make no provision, vehicle access may be as described in paragraphs 15.4 and 15.5, rather than Table 15.1.

Design of access routes and hardstandings

15.7Access routes and hardstandings should comply with the guidance in Table 15.2. Requirements can only apply to the site of the works.

It may not be reasonable to upgrade the route across a site to a small building. The building control body, in consultation with the fire and rescue service, should consider options from doing no work to upgrading certain features, such as sharp bends.

15.8Where access to an elevation is provided in accordance with Table 15.1, the following requirements should be met, depending on the building height.

a.Buildings up to 11m, excluding small buildings (paragraph 15.1): pump appliance access should be provided adjacent to the building for the specified percentage of the total perimeter.

b.Buildings over 11m: access routes should comply with the guidance in Diagram 15.2.

15.9Where access is provided for high reach appliances in accordance with Table 15.1, overhead obstructions (such as cables and branches) should be avoided in the zone shown in Diagram 15.2.

15.10Dead-end access routes longer than 20m require turning facilities, as in Diagram 15.3. Turning facilities should comply with the guidance in Table 15.2.

Source page 126

Source page 127

Fire and rescue service vehicles should not have to reverse more than 20m from the end of an access road.

Source page 128

Introduction

16.1Fire mains are installed for the fire and rescue service to connect hoses for water. They may be either of the following.

a.The ‘dry’ type, which are both of the following.

i.Normally kept empty.

ii.Supplied through a hose from a fire and rescue service pumping appliance.

b.The ‘wet’ type, which are both of the following.

i.Kept full of water.

ii.Supplied by pumps from tanks in the building.

There should be a facility to replenish a wet system from a pumping appliance in an emergency.

Provision of fire mains

16.2Buildings with firefighting shafts should have fire mains in both of the following.

a.The firefighting shafts.

b.Where necessary, in protected escape stairs.

The criteria for providing firefighting shafts and fire mains are given in Section 17.

16.3Buildings without firefighting shafts should be provided with fire mains where fire service vehicle access is not provided in accordance with Table 15.1. In these cases, outlets from fire mains should be located as described in paragraph 16.4, with a maximum hose distance of 45m from the fire main outlet to the furthest point, measured on a route suitable for laying a hose. Stairs do not need to be designed as firefighting shafts.

Design and construction of fire mains

16.4If a firefighting shaft is provided, outlets from fire mains should be within the protected stairway or protected lobby (see Diagram 17.1).

16.5Guidance on the design and construction of fire mains is given in BS 9990.

16.6Buildings with a storey more than 50m above fire service vehicle access level should be provided with wet fire mains. In all other buildings where fire mains are provided, either wet or dry fire mains are suitable.

16.7Fire service vehicle access to fire mains should be provided as described in paragraphs 15.4 and 15.5.

Source page 129

16.8A building requires additional fire hydrants if both of the following apply.

a.It has a compartment with an area more than 280m².

b.It is being erected more than 100m from an existing fire hydrant.

16.9If additional hydrants are required, these should be provided in accordance with the following.

a.For buildings provided with fire mains – within 90m of dry fire main inlets.

b.For buildings not provided with fire mains – hydrants should be both of the following.

i.Within 90m of an entrance to the building.

ii.A maximum of 90m apart.

16.10Each fire hydrant should be clearly indicated by a plate, fixed nearby in a conspicuous position, in accordance with BS 3251.

16.11Guidance on aspects of provision and siting of private fire hydrants is given in BS 9990.

Alternative supply of water

16.12An alternative source of water supply should be provided where any of the following apply.

a.No piped water supply is available.

b.Pressure and flow in the water main are insufficient.

c.An alternative source of supply is proposed.

16.13The alternative source of water supply should be one of the following, subject to consultation with the local fire and rescue service.

a.A charged static water tank with a minimum capacity of 45,000 litres.

b.A spring, river, canal or pond that is capable of fulfilling both of the following conditions.

i.Providing or storing a minimum of 45,000 litres of water at all times.

ii.Providing access, space and a hardstanding for a pumping appliance.

c.Any other water supply that the local fire and rescue service considers appropriate.

Source page 130

Introduction

17.1Facilities for fire and rescue, such as firefighting lifts, firefighting stairs and firefighting lobbies, are combined in protected firefighting shafts (Diagram 17.1). Section 8 gives guidance on the design and construction of protected shafts.

Source page 131

17.2A building with a storey more than 18m above the fire and rescue service vehicle access level should have one or more firefighting shafts containing a firefighting lift. The number and location of firefighting shafts should comply with paragraphs 17.4 to 17.7. Firefighting shafts are not required to serve a basement that is not large or deep enough to need one (see paragraph 17.3 and Diagram 17.2).

17.3A building with basement storeys should have firefighting shafts in accordance with the following.

a.There is a basement more than 10m below the fire and rescue service vehicle access level. The firefighting shafts should contain firefighting lifts.

b.There are two or more basement storeys, each with a minimum area of 900m². The firefighting shafts do not need to include firefighting lifts.

The building’s height and size determine whether firefighting shafts also serve upper storeys.

17.4Firefighting shafts should serve all storeys through which they pass.

17.5A minimum of two firefighting shafts should be provided to buildings with a storey that has both of the following.

a.A floor area of 900m² or more.

b.A floor level 18m or more above the fire and rescue service vehicle access level.

17.6At least two firefighting shafts, which do not need to include firefighting lifts, should be provided if buildings meet all of the following.

a.They are in the ‘shop and commercial’, ‘assembly and recreation’ or ‘industrial’ purpose group (purpose group 4, 5 or 6).

b.They have a storey area of 900m² or more.

c.They have a storey height of 7.5m or more above fire and rescue service vehicle access level.

Source page 132

Location of firefighting shafts

17.7Firefighting shafts and protected stairways should be positioned such that every part of each storey more than 18m above the fire and rescue service vehicle access level complies with the maximum distances given in paragraph 17.8. Distances should be measured from the fire main outlet on a route suitable for laying a hose.

17.8In any building, the hose laying distance should meet all of the following conditions.

a.A maximum of 60m from the fire main outlet in a firefighting shaft (see Diagram 17.3).

b.Additionally, where sprinklers have not been provided in accordance with Appendix E, the hose laying distance should be a maximum of 45m from a fire main outlet in a protected shaft (although this does not imply that the protected shaft needs to be designed as a firefighting shaft (see Diagram 17.3).

Source page 133

Source page 134

17.9Every firefighting stair and firefighting lift should be approached from the accommodation through a firefighting lobby. Both the stair and lobby of the firefighting shaft should be provided with a means of venting smoke and heat (see clause 27.1 of BS 9999).

Only services associated with the firefighting shaft, such as ventilation systems and lighting for the firefighting shaft, should pass through or be contained within the firefighting shaft.

17.10All firefighting shafts should have fire mains with outlet connections and valves at every storey.

17.11A firefighting lift installation includes all of the following.

a.Lift car.

b.Lift well.

c.Lift machinery space.

d.Lift control system.

e.Lift communications system.

The lift shaft should be constructed in accordance with Section 6 of BS 9999.

Firefighting lift installations should conform to BS EN 81-72 and BS EN 81-20.

Rolling shutters in compartment walls

17.12The fire and rescue service should be able to manually open and close rolling shutters without the use of a ladder.

Source page 135

Provision of smoke outlets

18.1Heat and smoke from basement fires vented via stairs can inhibit access for firefighting personnel. This may be reduced by providing smoke outlets, or smoke vents, which allow heat and smoke to escape from the basement levels to the open air. They can also be used by the fire and rescue service to let cooler air into the basements (Diagram 18.1).

18.2Each basement space should have one or more smoke outlets.

Where this is not practicable (for example, the plan area is deep and the amount of external wall is restricted by adjoining buildings), the perimeter basement spaces may be vented, with other spaces vented indirectly by opening connecting doors. This does not apply for place of special fire hazard (see paragraph 18.7).

If a basement is compartmented, each compartment should have one or more smoke outlets, rather than indirect venting.

A basement storey or compartment containing rooms with doors or windows does not need smoke outlets.

18.3Smoke outlets connecting directly to the open air should be provided from every basement storey, except for any basement storey that has both of the following.

a.A maximum floor area of 200m².

b.A floor a maximum of 3m below the adjacent ground level.

18.4Strong rooms do not need to be provided with smoke outlets.

Natural smoke outlets

18.5Smoke outlets should be both of the following.

a.Sited at high level in either the ceiling or wall of the space they serve.

b.Evenly distributed around the perimeter, to discharge to the open air.

18.6The combined clear cross-sectional area of all smoke outlets should be a minimum of 1/40 of the area of the floor of the storey they serve.

18.7Separate outlets should be provided from places of special fire hazard.

18.8If the smoke outlet terminates at a point that is not readily accessible, it should be kept unobstructed and covered only with a class A1 grille or louvre.

18.9If the smoke outlet terminates in a readily accessible position, it may be covered by a panel, stallboard or pavement light that can be broken out or opened. The position of covered smoke outlets should be suitably indicated.

Source page 136

18.10Outlets should not be placed where they prevent the use of escape routes from the building.

Mechanical smoke extract

18.11If basement storeys are fitted with a sprinkler system in accordance with Appendix E, a mechanical smoke extraction system may be provided as an alternative to natural venting. Sprinklers do not need to be installed on the other storeys unless needed for other reasons.

Car parks are not normally expected to be fitted with sprinklers (see Section 11 for guidance on car parks).

18.12The air extraction system should comply with all of the following.

a.It should give at least 10 air changes per hour.

b.It should be capable of handling gas temperatures of 300°C for not less than one hour.

c.It should do either of the following.

i.Be activated automatically if the sprinkler system activates.

ii.Be activated by an automatic fire detection system that conforms to BS 5839-1 (minimum L3 standard).

Further information on equipment for removing hot smoke is given in BS EN 12101-3.

Source page 137

18.13Outlet ducts or shafts, including any bulkheads over them (see Diagram 18.1), should be enclosed in construction of class A1 rating and fire resistance at least equal to that of the element through which they pass.

18.14Natural smoke outlet shafts should be separated from each other using construction of class A1 rating and fire resistance at least equal to that of the storeys they serve, where the shafts are either of the following.

a.From different compartments of the same basement storey.

b.From different basement storeys.

Basement car parks

18.15The provisions for ventilation of basement car parks in Section 11 satisfy the requirements for venting smoke from any basement used as a car park.

Source page 138

This section deals with the following regulation of the Building Regulations 2010.

Source page 139

The aim of this regulation is to ensure that the person responsible for the building has sufficient information relating to fire safety to enable them to manage the building effectively. The aim of regulation 38 will be achieved when the person responsible for the building has all the information to enable them to do all of the following.

a.Understand and implement the fire safety strategy of the building.

b.Maintain any fire safety system provided in the building.

c.Carry out an effective fire risk assessment of the building.

Source page 140

19.1For building work involving the erection or extension or a change of use of a relevant building (i.e. a building to which the Regulatory Reform (Fire Safety) Order 2005 or the Building Safety Act 2022 applies, or will apply), fire safety information should be given to the relevant dutyholder (responsible person or accountable person) at one of the following times, whichever is the earlier.

a.When the project is complete.

b.When the building or extension is first occupied.

19.2This section is a guide to the information that should be provided and is not exhaustive. Guidance is in terms of essential information and additional information for complex buildings; however, the level of detail required should be considered on a case-by-case basis.

Essential information

19.3The essential information provided should be sufficient to enable the relevant dutyholder to understand, operate and maintain the building (including the fire safety systems in it). It should make it clear how the fire safety arrangements of the building are intended to operate together. In cases where a fire safety strategy has been prepared (e.g. as part of the design and construction process for a building or building work), then this should be made available to the relevant dutyholder.

19.4Information on the location of fire protection measures may be sufficient. An as-built plan of the building should be provided showing all of the following.

a.Escape routes – this should include exit capacity (i.e. the maximum allowable number of people for each storey and for the building).

b.Fire resisting construction and location of fire-separating elements (including cavity barriers in walk-in spaces).

c.Fire doorsets, fire doorsets fitted with a self-closing device and other doors relevant to the fire safety strategy, such as doors equipped with relevant hardware.

d.Locations of fire detector heads (e.g. heat and smoke detectors), manual call points, fire alarm control and indicating equipment, fire alarm sounders, fire safety signage, emergency lighting, fire extinguishers, dry or wet fire mains and other firefighting equipment, and hydrants outside the building.

e.Any sprinkler systems, including isolating valves and control equipment.

f.Any smoke control systems, or ventilation systems with a smoke control function, including mode of operation and control systems.

Source page 141

g.Any high risk areas (e.g. heating machinery).

h.Any power supplies or power generating installations.

i.The location of secure information boxes.

19.5Details should be provided of all of the following.

a.Specifications of fire safety equipment provided, including routine maintenance schedules.

b.Any assumptions regarding the management of the building in the design of the fire safety arrangements.

c.Any provision enabling the evacuation of disabled people, which can be used when designing personal emergency evacuation plans.

d.Information for care homes should include the assessment for the number of beds in a compartment, as this should set out the expected number of staff and level of assistance of residents (see paragraph 2.39).

Additional information for complex buildings

19.6A detailed record should be provided of both of the following.

a.The fire safety strategy.

b.Procedures for operating and maintaining any fire protection measures. This should include an outline cause and effect matrix/strategy for the building.

Further guidance is available in clause 9 and Annex H of BS 9999.

19.7The records should include details of the following.

a.The fire safety strategy, including all assumptions in the design of the fire safety systems (such as fire load). Any risk assessments or risk analysis.

b.All assumptions in the design of the fire safety arrangements for the management of the building.

c.All of the following.

i.Escape routes (including occupant load and capacity of escape routes).

ii.Any provision to enable the evacuation of disabled people (including the location and mode of operation of evacuation lifts).

iii.Escape strategy (e.g. simultaneous or phased).

iv.Assembly points and/or muster stations.

d.All passive fire safety measures, including all of the following.

i.Compartmentation.

ii.Fire-separating elements.

iii.Fire resisting construction.

iv.Cavity barriers.

Source page 142

v.Fire doors, including fire doors fitted with a self-closing device and other doors relevant to the fire safety strategy, such as doors equipped with relevant hardware (e.g. electronic security locks).

vi.Fire dampers, fire and smoke dampers, and smoke control dampers.

vii.Fire shutters.

e.All of the following.

i.Fire detector heads (e.g. heat and smoke detectors).

ii.Manual call points.

iii.Fire alarm control and indicating equipment.

iv.Fire alarm sounders.

v.Emergency communications systems.

vi.CCTV.

vii.Fire safety signage.

viii.Emergency lighting.

ix.Fire extinguishers.

x.Dry or wet fire mains and other firefighting equipment.

xi.Other interior facilities for the fire and rescue service.

xii.Emergency control rooms.

xiii.Location of hydrants outside the building.

xiv.Other exterior facilities for the fire and rescue service.

xv.The location of secure information boxes.

f.All active fire safety measures, including both of the following.

i.Sprinkler system(s) design, including isolating valves and control equipment.

ii.Smoke control system(s) (or heating, ventilation and air conditioning system with a smoke control function) design, including any air inlets, smoke outlets, mode of operation and control systems.

g.Any high risk areas (e.g. heating machinery) and particular hazards.

h.Plans of the building as built, showing the locations of the above.

Source page 143

i.Both of the following.

i.Specifications of any fire safety equipment provided, including all of the following.

•Operational details.

•Operators’ manuals.

•Software.

•System zoning.

•Routine inspection, testing and maintenance schedules.

ii.Records of any acceptance or commissioning tests.

j.Any other details appropriate for the specific building.

Source page 144

NOTE: Except for the items marked * (which are from the Building Regulations 2010), these definitions apply only to Approved Document B.

NOTE: The terms defined below are key terms used in this document only. Refer to BS 4422 for further guidance on the definitions of common terms used in the fire safety industry which are not listed below.

Access room A room that the only escape route from an inner room passes through.

Alternative escape routes Escape routes that are sufficiently separated by direction and space or by fire resisting construction to ensure that one is still available if the other is affected by fire.

NOTE: A second stair, balcony or flat roof which enables a person to reach a place free from danger from fire is considered an alternative escape route for the purposes of a dwellinghouse.

Alternative exit One of two or more exits, each of which is separate from the other.

Appliance ventilation duct A duct to deliver combustion air to a gas appliance.

Atrium (plural atria) A continuous space that passes through one or more structural floors within a building, not necessarily vertically.

NOTE: Enclosed lift wells, enclosed escalator wells, building services ducts and stairs are not classified as atria.

Automatic release mechanism A device that normally holds a door open, but closes it automatically if any one of the following occurs.

•Smoke is detected by an automatic device of a suitable nature and quality in a suitable location.

•A hand-operated switch, fitted in a suitable position, is operated.

•The electricity supply to the device, apparatus or switch fails.

•The fire alarm system, if any, is operated.

Basement storey A storey with a floor that, at some point, is more than 1200mm below the highest level of ground beside the outside walls. (However, see Appendix B, paragraph B26, for situations where the storey is considered to be a basement only because of a sloping site.)

Boundary The boundary of the land that belongs to a building, or, where the land abuts a road, railway, canal or river, the centre line of that road, railway, canal or river.

***Building** Any permanent or temporary building but not any other kind of structure or erection. A reference to a building includes a reference to part of a building.

Building control body A term that includes both local authority building control and approved inspectors.

Cavity A space enclosed by elements of a building (including a suspended ceiling) or contained within an element, but that is not a room, cupboard, circulation space, protected shaft, or space within a flue, chute, duct, pipe or conduit.

Cavity barrier A construction within a cavity, other than a smoke curtain, to perform either of the following functions.

•Close a cavity to stop smoke or flame entering.

•Restrict the movement of smoke or flame within a cavity.

Ceiling Part of a building that encloses a room, protected shaft or circulation space and is exposed overhead.

NOTE: The soffit of a rooflight, but not the frame, is included as part of the surface of the ceiling. An upstand below a rooflight is considered as a wall.

Circulation space A space (including a protected stairway) mainly used as a means of access between a room and an exit from the building or compartment.

Source page 145

Common balcony A walkway, open to the air on one or more sides, that forms part of the escape route from more than one flat.

Common stair An escape stair that serves more than one flat.

Compartment (fire) A building or part of a building, comprising one or more rooms, spaces or storeys, that is constructed to prevent the spread of fire to or from another part of the same building or an adjoining building.

NOTE: A roof space above the top storey of a compartment is included in that compartment. (See also ‘Separated part’.)

Compartment wall or floor A fire resisting wall or floor to separate one fire compartment from another.

NOTE: Provisions relating to construction are given in Section 8.

Corridor access A design of a building containing flats, in which each flat is approached via a common horizontal internal access or circulation space, which may include a common entrance hall.

Curtain Part of a solar shading device which is set in motion by the operating system and fulfils the purpose of a blind, awning or shutter.

Dead end An area from which escape is possible in one direction only.

Direct distance The shortest distance from any point within the floor area to the nearest storey exit, measured within the external enclosures of the building, and ignoring walls, partitions and fittings other than the enclosing walls and partitions to protected stairways.

***Dwelling** Includes a dwellinghouse and a flat.

NOTE: A dwelling is a unit where one or more people live (whether or not as a sole or main residence) in either of the following situations.

•A single person or people living together as a family.

•A maximum of six people living together as a single household, including where care is provided for residents.

***Dwellinghouse** Does not include a flat or a building containing a flat.

Element of structure Any of the following.

•A member that forms part of the structural frame of a building, or any other beam or column.

•A loadbearing wall or loadbearing part of a wall.

•A floor.

•A gallery (but not a loading gallery, fly gallery, stage grid, lighting bridge, or any gallery provided for similar purposes or for maintenance and repair).

•An external wall.

•A compartment wall (including a wall that is common to two or more buildings).

NOTE: However, see the guidance to requirement B3, paragraph 7.3, for a list of structures that are not considered to be elements of structure.

Emergency lighting Lighting for use when the power supply to the normal lighting fails.

Escape lighting The part of the emergency lighting that is provided to ensure that the escape route is illuminated at all material times.

Escape route The route along which people can escape from any point in a building to a final exit.

Evacuation lift A lift that may be used to evacuate people in a fire.

Exit passageway A protected passageway that connects a protected stairway to a final exit.

NOTE: Exit passageways should be protected to the same standard as the stairway they serve.

Source page 146

External wall The external wall of a building includes all of the following.

•Anything located within any space forming part of the wall.

•Any decoration or other finish applied to any external (but not internal) surface forming part of the wall.

•Any windows and doors in the wall.

•Any part of a roof pitched at an angle of more than 70 degrees to the horizontal if that part of the roof adjoins a space within the building to which persons have access, but not access only for the purpose of carrying out repairs or maintenance.

Final exit The end of an escape route from a building that gives direct access to a street, passageway, walkway or open space, and is sited to ensure that people rapidly disperse away from the building so that they are no longer in danger from fire and/or smoke.

Fire alarm system Combination of components for giving an audible and/or other perceptible warning of fire.

Fire damper A mechanical or intumescent device within a duct or ventilation opening that operates automatically and is designed to resist the spread of fire.

Fire and smoke damper A fire damper which, in addition to the performance of the fire damper, resists the spread of smoke.

Fire doorset A door or shutter which, together with its frame and furniture as installed in a building, is intended (when closed) to resist the spread of fire and/or gaseous products of combustion and meets specified performance criteria to those ends.

Firefighting lift A lift with additional protection and with controls that enable it to be used by the fire and rescue service when fighting a fire. (See Section 17.)

Firefighting lobby A protected lobby that provides access from a firefighting stair to the accommodation area and to any associated firefighting lift.

Firefighting shaft A protected enclosure that contains a firefighting stair, firefighting lobbies and, if provided, a firefighting lift together with its machine room.

Firefighting stair A protected stairway that connects to the accommodation area through only a firefighting lobby.

Fire resisting (Fire resistance) The ability of a component or a building to satisfy, for a stated period of time, some or all of the appropriate criteria given in the relevant standard.

Fire-separating element A compartment wall, compartment floor, cavity barrier and construction that encloses a protected escape route and/or a place of special fire hazard.

Fire-stop (Fire-stopping) A seal provided to close an imperfection of fit or design tolerance between elements or components, to restrict the spread of fire and smoke.

Flat A flat is a separate and self-contained premises constructed or adapted for use for residential purposes and forming part of a building from some other part of which it is divided horizontally.

Gallery A floor or balcony that does not extend across the full extent of a building’s footprint and is open to the floor below.

Habitable room A room used, or intended to be used, for people to live in (including, for the purposes of Approved Document B Volumes 1 and 2, a kitchen, but not a bathroom).

Height (of a building or storey for the purposes of Approved Document B Volumes 1 and 2)

Source page 147

•Height of a building is measured as shown in Appendix D, Diagram D4.

•Height of the floor of the top storey above ground level is measured as shown in Appendix D, Diagram D6.

Inner room Room from which escape is possible only by passing through another room (the access room).

Live/work unit A flat that is a workplace for people who live there, its occupants, and for people who do not live on the premises.

Means of escape Structural means that provide one or more safe routes for people to go, during a fire, from any point in the building to a place of safety.

Measurement

•Width of a doorway, cubic capacity, area, height of a building and number of storeys are measured as shown in Appendix D, Diagrams D1 to D6.

•Occupant number, travel distance, escape route and stairs are measured as described in Appendix D, paragraphs D1 to D4.

Notional boundary A boundary presumed to exist between two buildings on the same site.

Open spatial planning The internal arrangement of a building in which more than one storey or level is contained in one undivided volume, e.g. split-level floors. For the purposes of this document there is a distinction between open spatial planning and an atrium space.

Perimeter (of a building) The maximum aggregate plan perimeter, found by vertical projection onto a horizontal plane. (See Section 15.)

Pipe Includes pipe fittings and accessories. The definition of ‘pipe’ excludes a flue pipe and a pipe used for ventilating purposes, other than a ventilating pipe for an above-ground drainage system.

Place of special fire hazard A room such as any of the following.

•Oil-filled transformer room.

•Switch gear room.

•Boiler room.

•Storage space for fuel or other highly flammable substance(s).

•Room that houses a fixed internal combustion engine.

Platform floor (also called an access or raised floor) A floor that is supported by a structural floor, but with an intervening cavity to house services.

Protected circuit An electrical circuit that is protected against fire.

Protected corridor/lobby A corridor or lobby that is adequately protected from fire in adjoining areas by fire resisting construction.

Protected entrance hall/landing A circulation area, consisting of a hall or space in a flat, that is enclosed with fire resisting construction other than an external wall of a building.

Protected shaft A shaft that enables people, air or objects to pass from one compartment to another, and which is enclosed with fire resisting construction.

Protected stairway A stair that leads to a final exit to a place of safety and that is adequately enclosed with fire resisting construction. Included in the definition is any exit passageway between the foot of the stair and the final exit.

Purpose group A classification of a building according to the purpose to which it is intended to be put. (See Table 0.1.)

Relevant boundary The boundary or notional boundary that one side of the building faces and/or coincides with, and that is parallel to or at an angle of a maximum of 80 degrees to that side of the building.

Source page 148

Rooflight A dome light, lantern light, skylight, ridge light, glazed barrel vault or other element to admit daylight through a roof.

Room An enclosed space within a building that is not used solely as a circulation space. The term includes not only conventional rooms, but also cupboards that are not fittings and large spaces such as warehouses and auditoria. The term does not include cavities such as ducts, ceiling cavities and roof spaces.

School A place of education for children between 2 and 19 years old. The term includes nursery schools, primary schools and secondary schools as defined in the Education Act 1996.

Self-closing device A device that closes a door, when open at any angle, against a door frame.

Separated part (of a building) Part of a building that is separated from another part of the same building by a compartment wall. The wall runs the full height of the part and is in one vertical plane. (See Appendix D, Diagram D5.)

Sheltered housing Includes two or more dwellings in the same building or on adjacent sites, designed and constructed as residential accommodation for vulnerable or elderly people who receive, or will receive, a support service.

Single storey building A building that consists of a ground storey only. Basements are not counted as storeys in a building (see Appendix D). A separated part that consists of a ground storey only, with a roof to which access is only provided for repair or maintenance, may be treated as a single storey building.

Site (of a building) The land occupied by the building, up to the boundaries with land in other ownership.

Solar shading device A device attached to the external surface of an external wall for reducing heat gain within a building by shading or deflecting sunlight.

Specified attachment Includes any of the following.

•A balcony attached to an external wall.

•A device for reducing heat gain within a building by deflecting sunlight which is attached to an external wall.

•A solar panel attached to an external wall.

Storey Includes any of the following.

•Any gallery in an assembly building (purpose group 5).

•Any gallery in any other type of building if its area is more than half that of the space into which it projects.

•A roof, unless it is accessible only for maintenance and repair.

Source page 149

Suspended ceiling (fire-protecting) A ceiling suspended below a floor that adds to the fire resistance of the floor.

Thermoplastic material Any synthetic polymeric material that has a softening point below 200°C if tested to BS EN ISO 306 Method A120. Specimens for this test may be fabricated from the original polymer where the thickness of material of the end product is less than 2.5mm.

Travel distance (unless otherwise specified, e.g. as in the case of flats) The distance that a person would travel from any point within the floor area to the nearest storey exit, determined by the layout of walls, partitions and fittings.

Unprotected area (in relation to a side or external wall of a building) All of the following are classed as unprotected areas.

•Any part of the external wall that has less than the relevant fire resistance set out in Section 13.

•Any part of the external wall constructed of material more than 1mm thick if that material does not have a class B-s3, d2 rating or better, which is attached or applied, whether for cladding or any other purpose.

•Windows, doors or other openings. This does not include windows that are designed and glazed to give the necessary level of fire resistance and that are not openable.

Source page 150

Introduction

B1Much of the guidance in this document is given in terms of performance classifications in relation to British or European Standards. In such cases, it will be necessary to demonstrate that a system or product can meet the relevant performance classification. This will be achieved if the system or product complies with one of the following.

a.They should be in accordance with a specification or design that has been shown by specific test(s) to be capable of meeting that performance classification.

b.They should have been designed by using relevant design standards in order to meet that performance classification.

c.They should have been assessed by applying relevant test evidence, in lieu of carrying out a specific test, as being capable of meeting that performance classification.

NOTE: Some products are subject to Classification Without Further Testing (CWFT). For the purposes of this approved document, such products can be considered to have been shown to be capable of meeting a performance specification as per paragraph B1a.

B2Any test evidence used to demonstrate the fire performance classification of a product or system should be carefully checked to ensure that it is applicable to the intended use. Small differences in detail, such as fixing method, joints, dimensions, the introduction of insulation materials and air gaps (ventilated or not), might significantly affect the performance and should be tested or assessed in accordance with paragraph B1.

B3Assessments should not be regarded as a way to avoid a test where one is necessary. Assessments should only be carried out where sufficient relevant test evidence is available. Relevant test evidence is unlikely to be provided by test standards which have different classification criteria.

B4Where it is proposed to assess the classification of a product or system in lieu of carrying out a specific test (as in paragraph B1c), this should be done in accordance with the relevant standard for extended application for the test in question and should include details of the test evidence that has been used to support the assessment.

For performance classifications where there is no specific standard for extended application, assessment reports should be produced in accordance with the principles of BS EN 15725 and should include details of the test evidence that has been used to support the assessment. In cases where the end use application is not covered by the extended application standard and an assessment is the only other suitable approach, then further information on best practice is provided in the Passive Fire Protection Forum’s Guide to Undertaking Technical Assessments of the Fire Performance of Construction Products Based on Fire Test Evidence. The same principle should be followed for assessments as described in paragraph B2.

NOTE: Regulation 7(2) limits components used in or on the external walls of certain buildings to materials achieving class A2-s1, d0 or class A1 (see Section 12). Assessments cannot be used to demonstrate compliance with this requirement.

Source page 151

B5Tests and assessments should be carried out by organisations with the necessary expertise. For example, organisations listed as ‘notified bodies’ in accordance with the European Construction Products Regulation or laboratories accredited by the United Kingdom Accreditation Service (UKAS) for the relevant test standard can be assumed to have the necessary expertise.

NOTE: Standard fire tests do not directly measure fire hazard. They measure or assess the response of a material or system to exposure to one or more aspects of fire conditions. Performance in fire tests is only one of a number of factors that should be taken into account.

Reaction to fire

B6Reaction to fire relates to the degree to which a product will contribute, by its own decomposition, to a fire under specified conditions. Products, other than flooring, are classified as A1, A2, B, C, D, E or F (with class A1 being the highest performance and F being the lowest) in accordance with BS EN 13501-1. Class F is assigned when a product fails to attain class E. Untested products cannot be classified in accordance with BS EN 13501-1.

Materials covered by the Classification Without Further Testing (CWFT) process can be found by accessing the European Commission’s website https://eur-lex.europa.eu/.

B7The classes of reaction to fire performance of A2, B, C, D and E are accompanied by additional classifications related to the production of smoke (s1, s2, s3), with s1 indicating the lowest production, and/or flaming droplets/particles (d0, d1, d2), with d0 indicating the lowest production.

NOTE: When a classification includes s3, d2 this means that there is no limit set for smoke production and/or flaming droplets/particles.

B8To reduce the testing burden on manufacturers, BS EN 13238 defines a number of standard substrates that produce test results representative of different end use applications. The classification for reaction to fire achieved during testing is only valid when the product is used within this direct field of application, i.e. when the product is fixed to a substrate of that class in its end use. The standard substrate selected for testing should take account of the intended end use applications (field of application) of the product and represent end use substrates that have a density of a minimum of 75% of the standard substrate’s nominal density.

B9Standard substrates include gypsum plasterboard (BS EN 520) with a density of 700+/-100kg/m³, calcium silicate board (BS EN 14306) 870+/-50kg/m³ and fibre-cement board 1800+/-200kg/m³.

NOTE: Standard calcium silicate board is not representative of gypsum plasterboard end use (due to the paper layer), but would be representative of most gypsum plasters (with densities of more than 650kg/m³).

NOTE: Classifications based on tests using a plasterboard substrate would also be acceptable for products bonded to a gypsum plaster end use substrate.

Source page 152

B10Thermoplastic material is any synthetic polymeric material that has a softening point below 200°C if tested to BS EN ISO 306 Method A120. Products formed from these materials cannot always be classified in the normal way. In those circumstances the following approach can be followed.

B11Thermoplastic materials used for window glazing, rooflights and lighting diffusers within suspended ceilings do not need to meet the criteria within paragraph B18 onwards, if the guidance to requirements B2 and B4 is followed.

B12For the purposes of requirements B2 and B4, thermoplastic materials should be classified as TP(a) rigid, TP(a) flexible or TP(b), as follows:

a.TP(a) rigid

i.rigid solid uPVC sheet

ii.solid (as distinct from double- or multi-skinned) polycarbonate sheet a minimum of 3mm thick

iii.any other rigid thermoplastic product, a specimen of which (at the thickness of the product as put on the market), when tested to BS 2782-0 Method 508A, performs so that both:

•the test flame extinguishes before the first mark

•the duration of flaming or afterglow does not exceed 5 seconds following removal of the burner.

b.TP(a) flexible

Flexible products a maximum of 1mm thick that comply with the Type C requirements of BS 5867-2 when tested to BS 5438 Test 2 with the flame applied to the surface of the specimens for 5, 15, 20 and 30 seconds respectively, but excluding the cleansing procedure; and

c.TP(b)

i.rigid solid polycarbonate sheet products a maximum of 3mm thick, or multi-skinned polycarbonate sheet products that do not qualify as TP(a) by test

ii.other products which, when a specimen of the material between 1.5 and 3mm thick is tested in accordance with BS 2782-0 Method 508A, have a maximum rate of burning of 50mm/minute.

NOTE: If it is not possible to cut or machine a 3mm thick specimen from the product, then a 3mm test specimen can be moulded from the same material as that used to manufacture the product.

B13A thermoplastic material alone, when used as a lining to a wall or ceiling cannot be assumed to protect a substrate. The surface rating of both thermoplastic material and substrate must therefore meet the required classification.

If, however, the thermoplastic material is fully bonded to a non-thermoplastic substrate, then only the surface rating of the composite needs to meet the required classification.

Source page 153

Effective until 1 September 2029 – see 2029 amendment, page 152

Roofs

B14Performance of the resistance of roofs to external fire exposure is measured in terms of penetration through the roof construction and the spread of flame over its surface.

B15Roof constructions are classified within the European system as BROOF(t4), CROOF(t4), DROOF(t4), EROOF(t4) or FROOF(t4) in accordance with BS EN 13501-5. BROOF(t4) indicates the highest performance and FROOF(t4) the lowest.

B16BS EN 13501-5 refers to four separate roof tests. The suffix (t4) used in paragraph B15 indicates that Test 4 is to be used for the purposes of this approved document.

B17This document uses the European classification system for roof covering set out in BS EN 13501-5; however, there may be some products or systems whose performance will need to be assessed based on the recommendations of paragraphs B1 to B5 as being capable of meeting that performance classification.

Fire resistance

B18Common to all of the provisions of Part B of the Building Regulations is the property of fire resistance. Fire resistance is a measure of one or more of the following.

a.Resistance to collapse (loadbearing capacity), which applies to loadbearing elements only, denoted R in the European classification of the resistance to fire performance.

b.Resistance to fire penetration (integrity), denoted E in the European classification of the resistance to fire performance.

c.Resistance to the transfer of excessive heat (insulation), denoted I in the European classification of the resistance to fire performance.

B19The standards of fire resistance necessary for a particular building are based on assumptions about the severity of fires and the consequences should an element fail. Fire severity is estimated in very broad terms from the use of the building (its purpose group), on the assumption that the building contents (which constitute the fire load) are similar for buildings with the same use.

B20Because the use of buildings may change, a precise estimate of fire severity based on the fire load due to a particular use may be misleading. Therefore if a fire engineering approach of this kind is adopted, the likelihood that the fire load may change in the future needs to be considered.

B21Performance in terms of the fire resistance to be achieved by elements of structure, doors and other forms of construction is classified in accordance with one of the following.

a.BS EN 13501-2.

b.BS EN 13501-3.

c.BS EN 13501-4.

Source page 154

B22Fire resistance is measured in minutes. This relates to time elapsed in a standard test and should not be confused with real time.

B23The fire resistance necessary for different circumstances is set out in the following tables.

a.Table B1 gives the specific requirements for each element of structure.

b.Table B2 sets out the minimum periods of fire resistance for elements of structure.

c.Table B3 sets out limitations on the use of uninsulated fire resisting glazed elements.

B24This document uses the European classification system for fire resistance set out in BS EN 13501-2 to 4; however, there may be some products lawfully on the market using the classification system set out in previous editions. In those situations the alternative classifications given in Table B1 can be used.

Source page 155

Source page 156

Source page 157

Source page 158

Source page 159

Source page 160

Source page 161

B25The following guidance should be used when applying the fire resistance standards in Table B2.

a.If one element of structure supports or carries or gives stability to another, the fire resistance of the supporting element should be no less than the minimum period of fire resistance for the other element (whether that other element is loadbearing or not). In some circumstances, it may be reasonable to vary this principle, for example:

i.if the supporting structure is in the open air and is not likely to be affected by the fire in the building

ii.if the supporting structure is in a different compartment, with a fire-separating element (that has the higher standard of fire resistance) between the supporting and the separated structure

iii.if a plant room on the roof needs greater fire resistance than the elements of structure that support it.

b.If an element of structure forms part of more than one building or compartment, that element should be constructed to the standard of the higher of the relevant provisions.

c.If, due to the slope of the ground, one side of a basement is open at ground level (allowing smoke to vent and providing for access for firefighting) for elements of structure in that storey it may be appropriate to adopt the standard of fire resistance that applies to above-ground structures.

d.Although most elements of structure in a single storey building may not need fire resistance, fire resistance is needed if one of the following applies to the element.

i.It is part of, or supports, an external wall, and there is provision in the guidance on requirement B4 to limit the extent of openings and other unprotected areas in the wall.

ii.It is part of, or supports, a compartment wall, including a wall that is common to two or more buildings.

iii.It supports a gallery.

B26For the purposes of this paragraph, the ground storey of a building that has one or more basement storeys and no upper storeys may be considered as a single storey building. The fire resistance of the basement storeys should be that specified for basements.

Source page 162

Source page 163

Source page 164

Introduction

B1The guidance in this document is given in terms of performance classifications in relation to European Standards. In such cases, it will be necessary to demonstrate that a system or product can meet the relevant performance classification. This will be achieved if the system or product complies with one of the following.

a.They should be in accordance with a specification or design that has been shown by specific test(s) to be capable of meeting that performance classification.

b.They should have been designed by using relevant design standards in order to meet that performance classification.

c.They should have been assessed by applying relevant test evidence, in lieu of carrying out a specific test, as being capable of meeting that performance classification.

B2Any test evidence used to demonstrate the fire performance classification of a product or system should be carefully checked to ensure that it is applicable to the intended use. Small differences in detail, such as fixing method, joints, dimensions, the introduction of insulation materials and air gaps (ventilated or not), might significantly affect the performance and should be tested or assessed in accordance with paragraph B1.

B3Assessments should not be regarded as a way to avoid a test where one is necessary. Assessments should only be carried out where sufficient relevant test evidence is available. Relevant test evidence is unlikely to be provided by test standards which have different classification criteria.

B4Where it is proposed to assess the classification of a product or system in lieu of carrying out a specific test (as in paragraph B1c), this should be done in accordance with the relevant standard for extended application for the test in question and should include details of the test evidence that has been used to support the assessment.

For performance classifications where there is no specific standard for extended application, assessment reports should be produced in accordance with the principles of BS EN 15725 and should include details of the test evidence that has been used to support the assessment. In cases where the end use application is not covered by the extended application standard and an assessment is the only other suitable approach, then further information on best practice is provided in the Passive Fire Protection Forum’s Guide to Undertaking Technical Assessments of the Fire Performance of Construction Products Based on Fire Test Evidence. The same principle should be followed for assessments as described in paragraph B2.

Source page 165

B5Tests and assessments should be carried out by organisations with the necessary expertise. For example, organisations listed as ‘notified bodies’ in accordance with the European Construction Products Regulation or laboratories accredited by the United Kingdom Accreditation Service (UKAS) for the relevant test standard can be assumed to have the necessary expertise.

Reaction to fire

B6Reaction to fire relates to the degree to which a product will contribute, by its own decomposition, to a fire under specified conditions. Products, other than floorings, are classified as A1, A2, B, C, D, E or F (with class A1 being the highest performance and F being the lowest) in accordance with BS EN 13501-1. Class F is assigned when a product fails to attain class E. Untested products cannot be classified in accordance with BS EN 13501-1.

Materials covered by the Classification Without Further Testing (CWFT) process can be found by accessing the European Commission’s website https://eur-lex.europa.eu/.

B7The classes of reaction to fire performance of A2, B, C, D and E are accompanied by additional classifications related to the production of smoke (s1, s2, s3), with s1 indicating the lowest production, and/or flaming droplets/particles (d0, d1, d2), with d0 indicating the lowest production.

B8To reduce the testing burden on manufacturers, BS EN 13238 defines a number of standard substrates that produce test results representative of different end use applications. The classification for reaction to fire achieved during testing is only valid when the product is used within this direct field of application, i.e. when the product is fixed to a substrate of that class in its end use. The standard substrate selected for testing should take account of the intended end use applications (field of application) of the product and represent end use substrates that have a density of a minimum of 75% of the standard substrate’s nominal density.

B9Standard substrates include gypsum plasterboard (BS EN 520) with a density of 700+/-100kg/m³, calcium silicate board (BS EN 14306) 870+/-50kg/m³ and fibre-cement board 1800+/-200kg/m³.

Source page 166

B10Thermoplastic material is any synthetic polymeric material that has a softening point below 200°C if tested to BS EN ISO 306 Method A120. Products formed from these materials cannot always be classified in the normal way. In those circumstances the following approach can be followed.

B11Thermoplastic materials used for window glazing, rooflights and lighting diffusers within suspended ceilings do not need to meet the criteria within paragraph B18 onwards, if the guidance to requirements B2 and B4 is followed.

B12For the purposes of requirements B2 and B4, thermoplastic materials should be classified as TP(a) rigid, TP(a) flexible or TP(b), as follows:

a.TP(a) rigid

i.rigid solid uPVC sheet

ii.solid (as distinct from double- or multi-skinned) polycarbonate sheet a minimum of 3mm thick

iii.any other rigid thermoplastic product, a specimen of which (at the thickness of the product as put on the market), when tested to BS 2782-0 Method 508A, performs so that both:

•the test flame extinguishes before the first mark

•the duration of flaming or afterglow does not exceed 5 seconds following removal of the burner.

b.TP(a) flexible

Flexible products a maximum of 1mm thick that comply with the Type C requirements of BS 5867-2 when tested to BS 5438 Test 2 with the flame applied to the surface of the specimens for 5, 15, 20 and 30 seconds respectively, but excluding the cleansing procedure; and

c.TP(b)

i.rigid solid polycarbonate sheet products a maximum of 3mm thick, or multi-skinned polycarbonate sheet products that do not qualify as TP(a) by test

ii.other products which, when a specimen of the material between 1.5 and 3mm thick is tested in accordance with BS 2782-0 Method 508A, have a maximum rate of burning of 50mm/minute.

B13A thermoplastic material alone when used as a lining to a wall or ceiling cannot be assumed to protect a substrate. The surface rating of both thermoplastic material and substrate must therefore meet the required classification.

If, however, the thermoplastic material is fully bonded to a non-thermoplastic substrate, then only the surface rating of the composite needs to meet the required classification.

Source page 167

B14Performance of the resistance of roofs to external fire exposure is measured in terms of penetration through the roof construction and the spread of flame over its surface.

B15Roof constructions are classified within the European system as B_ROOF(t4), C_ROOF(t4), D_ROOF(t4), E_ROOF(t4) or F_ROOF(t4) in accordance with BS EN 13501-5. B_ROOF(t4) indicates the highest performance and F_ROOF(t4) the lowest.

B16BS EN 13501-5 refers to four separate roof tests. The suffix (t4) used in paragraph B15 indicates that Test 4 is to be used for the purposes of this approved document.

B17This document uses the European classification system for roof covering set out in BS EN 13501-5; however, there may be some products or systems whose performance will need to be assessed based on the recommendations of paragraphs B1 to B5 as being capable of meeting that performance classification.

Fire resistance

B18Common to all of the provisions of Part B of the Building Regulations is the property of fire resistance. Fire resistance is a measure of one or more of the following criteria.

a.Resistance to collapse (loadbearing capacity), which applies to loadbearing elements only, denoted R in the European classification of the resistance to fire performance.

b.Resistance to fire penetration (integrity), denoted E in the European classification of the resistance to fire performance.

c.Resistance to the transfer of excessive heat (insulation), denoted I in the European classification of the resistance to fire performance.

B19The standards of fire resistance necessary for a particular building are based on assumptions about the severity of fires and the consequences should an element fail. Fire severity is estimated in very broad terms from the use of the building (its purpose group), on the assumption that the building contents (which constitute the fire load) are similar for buildings with the same use.

B20Because the use of buildings may change, a precise estimate of fire severity based on the fire load due to a particular use may be misleading. Therefore if a fire engineering approach of this kind is adopted, the likelihood that the fire load may change in the future needs to be considered.

B21Performance in terms of the fire resistance to be achieved by elements of structure, doors and other forms of construction is classified in accordance with one of the following.

a.BS EN 13501-2.

b.BS EN 13501-3.

c.BS EN 13501-4.

Source page 168

B22Fire resistance is measured in minutes. This relates to time elapsed in a standard test and should not be confused with real time.

B23The fire resistance necessary for different circumstances is set out in the following tables.

a.Table B1 gives the specific requirements for each element of structure.

b.Table B2 sets out the minimum periods of fire resistance for elements of structure.

c.Table B3 sets out limitations on the use of uninsulated fire resisting glazed elements.

B24This document uses the European classification system (REI) for fire resistance set out in BS EN 13501-2 to 4. Fire resistance is expressed as REI X, where X is the period of fire resistance in minutes in terms of loadbearing capacity (R), integrity (E) and insulation (I). Products or systems cannot typically assume a European class unless they have been tested and classified accordingly.

B25Products or systems achieving the European classification (REI) should be specified wherever possible. However, there may be some products or systems that have been assessed as being capable of meeting a fire resistance performance classification. When assessed, products or systems should follow the relevant test standards to indicate their fire resistance performance in terms of loadbearing capacity, integrity and insulation based on the recommendations of paragraphs B1 to B5. In those situations, the performance classifications given in Table B1 and Table B2 may be used.

Source page 169

Source page 170

Source page 171

Source page 172

Source page 173

2029 amendment – effective from 2 September 2029

i.Beams supporting concrete floors, maximum Hp/A=230m⁻¹ operating under full design load.

ii.Free-standing columns, maximum Hp/A=180m⁻¹ operating under full design load.

iii.Wind bracing and struts, maximum Hp/A=210m⁻¹ operating under full design load.

Guidance is also available in BS EN 1993-1-2.

Source page 174

B26The following guidance should be used when applying the fire resistance standards in Table B2.

a.If one element of structure supports or carries or gives stability to another, the fire resistance of the supporting element should be no less than the minimum period of fire resistance for the other element (whether that other element is loadbearing or not). In some circumstances, it may be reasonable to vary this principle, for example:

i.if the supporting structure is in the open air and is not likely to be affected by the fire in the building

ii.if the supporting structure is in a different compartment, with a fire-separating element (that has the higher standard of fire resistance) between the supporting and the separated structure

iii.if a plant room on the roof needs greater fire resistance than the elements of structure that support it.

b.If an element of structure forms part of more than one building or compartment, that element should be constructed to the standard of the higher of the relevant provisions.

c.If, due to the slope of the ground, one side of a basement is open at ground level (allowing smoke to vent and providing access for firefighting) for elements of structure in that storey it may be appropriate to adopt the standard of fire resistance that applies to above-ground structures.

d.Although most elements of structure in a single storey building may not need fire resistance, fire resistance is needed if one of the following applies to the element.

i.It is part of, or supports, an external wall, and there is provision in the guidance on requirement B4 to limit the extent of openings and other unprotected areas in the wall.

ii.It is part of, or supports, a compartment wall, including a wall that is common to two or more buildings.

iii.It supports a gallery.

B27For the purposes of this paragraph, the ground storey of a building that has one or more basement storeys and no upper storeys may be considered as a single storey building. The fire resistance of the basement storeys should be that specified for basements.

Source page 175