Circular letter regarding single stair provisions in very tall residential buildings and applicability of the Approved Documents

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cc: The Chief Executive:

Combined Authorities and County Councils in England

National Park Authorities in England

Chief Fire Officer: Fire and Rescue Authorities in England

22August 2022

Dear all,

Single stair provisions in very tall residential buildings and applicability of the Approved Documents

Following recent concerns over design proposals for very tall residential buildings with single stairs being designed using Approved Document B, the Department has sought advice from the Building Regulation Advisory Committee (BRAC). BRAC has expressed concerns that some design proposals appear to be based on a misunderstanding of the applicability, and selective reading, of the Approved Documents. It was also unclear how the design proposals would demonstrate compliance with the functional requirements of the Building Regulations, particularly relating to means of escape.

The Department agrees with BRAC and is concerned that some very tall residential buildings are being designed on the incorrect premise that the guidance in the Approved Document is suitable for these types of uncommon building situations without due consideration by the designers on the applicability of the guidance. I am writing to remind you of the need to consider the suitability of the design guidance in Approved Document B and the need for robust, evidence based, design by suitably competent professionals, particularly in relation to fire and structural safety issues of uncommon building situations such as very tall residential buildings proposed with a single stair.

Building work must be designed and built to 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 the functional requirements and to provide clear evidence of

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compliance with those requirements, such as detailed fire engineering analysis. While the legal requirements are contained in the Building Regulations, the approved documents contain guidance on how to meet those legal requirements in common building situations. The Approved Documents may not provide appropriate guidance if the case is unusual in terms of its design, setting, use, scale or technology.

The Manual to the Building Regulations already sets out that “Non-standard conditions may include any of the following:

a. difficult ground conditions b. buildings with unusual occupancies or high levels of complexity c. very large or very tall buildings d. large timber buildings e. some buildings that incorporate modern construction methods.”

In line with the Building Control Performance Standards, it is the Department’s expectation that building control bodies use reasonable skill and care in discharging their legal duties which includes understanding the guidance and its applicability. Where design proposals are not for common building situations – such as very tall residential buildings – then building control bodies should be clear with the applicant and/or their design teams at the earliest opportunity and emphasise the need for designs supported by robust evidence including where necessary the level of technical analysis required to demonstrates compliance with the building regulations, particularly for fire and structural safety aspects.

The Department would expect that robust fire safety provisions are made to demonstrate compliance with Part B of Building Regulations in the case of non-standard conditions, which include very tall single stair residential buildings. Such situations are likely to require a detailed fire engineering analysis.

Further guidance on the Building Regulations system and its associated guidance can be found in the Manual to the Building Regulations.

Finally, I would like to take the opportunity to remind you that the Department is currently undertaking a significant programme of research as part of the technical review of Approved Document B. This technical review will provide the opportunity to analyse the evidence base of some of the provisions in the guidance to the Building Regulations and includes research on means of escape in blocks of flats. See further information on the technical review.

If you have any questions regarding this letter, please contact us at Enquiries.BR@levellingup.gov.uk

Yours faithfully,

V Molho

Deputy Director

Technical Policy Division

Building Safety Portfolio