Building regulations in Wales

How do building regulations in Wales differ from England?

Building regulations in Wales have been made by the Welsh Ministers, not the UK Government, since 31 December 2011. Wales still uses the Building Regulations 2010 as its base, but they have been amended separately, so Wales now has its own Approved Documents, sprinklers in all new homes, different energy standards and, from 1 July 2026, its own version of the higher-risk building regime.

Functions were transferred by the Welsh Ministers (Transfer of Functions) (No. 2) Order 2009, in force on 31 December 2011. One exclusion remained: "excepted energy buildings", such as some power stations, stayed with the UK Government until section 54 of the Wales Act 2017 removed the exception from 1 April 2018. Both nations still use the Building Act 1984 and the same numbering of Schedule 1 Parts A to S, which is why the systems look similar on the surface.

Never assume an English Approved Document, circular or date applies in Wales.

Do Welsh Approved Documents differ from English ones?

Yes. The Welsh Government publishes its own Approved Documents on gov.wales, approved by the Welsh Ministers, and English amendments since 2011 do not automatically apply.

Some still share their technical content with older English editions, but they are separate documents with separate amendment histories. Practical points to watch:

• ✓Check the gov.wales version. For each Part, the current Welsh document and any amendment slips are listed on the relevant gov.wales guidance page.
• ✓Check the date. Approved Document O came into force on 15 June 2022 in England but on 23 November 2022 in Wales.
• ✓Check the slips. Approved Document B in Wales has its own amendment slips, including amendments to Volumes 1 and 2 applicable from 20 December 2025.
• ✓Check the language. Welsh legislation and Approved Documents are published in English and Welsh, with equal legal status for legislation.

Sprinklers in all new homes

Since 1 January 2016, new dwelling-houses and flats in Wales, including those formed by a material change of use, must have an automatic fire suppression system under regulation 37A. Care homes and rooms for residential purposes have been covered since 30 April 2014.

The requirement was introduced by the Building Regulations &c. (Amendment) (Wales) Regulations 2013, following the Domestic Fire Safety (Wales) Measure 2011. The 2014 stage excluded hostels, hotels, prisons, young offender institutions and hospitals. Dwellings with plans or notices submitted before 1 January 2016 were exempt only if work started by 1 January 2017.

Exemptions apply to temporary buildings intended for two years or less, and to listed buildings, conservation-area buildings and scheduled monuments where a system would unacceptably alter their character. Systems are normally designed to BS 9251 for domestic and residential use. For architects, this affects water supply, plant space and the fire strategy from the start of every Welsh residential project, including small conversions.

Part L in Wales, and what changes in 2027

The current Welsh energy standard has applied since 23 November 2022. The 2026 editions of Approved Document L Volumes 1 and 2 and Approved Document F Volume 1 take effect on 4 March 2027, three weeks before England's equivalent changes.

The 2022 standard came in through SI 2022/564, which introduced new Approved Documents L Volume 1, F Volume 1 and O for Wales. The Welsh Government described it as a 37% cut in carbon emissions from new homes compared with the previous standard. A follow-on amendment extended the on-site electricity generation requirement (L2) to non-domestic buildings from 29 March 2023. The next step is approved by SI 2026/60 and Circular WGC 006/2026.

Key changes confirmed

• A new Energy Use Intensity (EUI) metric replacing the dwelling energy efficiency rate.
• A new Schedule 1 requirement for on-site renewable electricity generation when a dwelling, or a building containing a dwelling, is built.
• A notional dwelling based on a heat pump, with the external wall U-value improved from 0.15 to 0.13 W/m²K.
• A 45°C maximum flow temperature for wet heating systems in new dwellings.
• The Home Energy Model as the calculation method, with SAP 10.3 used in the interim.

Part O in Wales is not changed by this package. The Welsh Government consulted in 2025 on Part O proposals for certain existing dwellings and has said responses will be published separately.

How the Building Safety Act applies in Wales

Wales adopted the design and construction parts of the Building Safety Act 2022 later than England, and with differences. The new building control regime came into force in Wales on 1 July 2026.

It was brought in by the Building (Higher-Risk Buildings Procedures) (Wales) Regulations 2025, the Building etc. (Amendment) (No. 2) (Wales) Regulations 2025 and the Building Safety Act 2022 (Commencement No. 6) (Wales) Regulations 2025.

What changed for all building work

Dutyholders

Clients, designers and contractors have duties for building regulations compliance, with principal designer and principal contractor roles that mirror CDM 2015.

Applications

Building control applications replace the deposit of plans.

Commencement

A statutory definition of commencement; approvals lapse automatically if work has not started within three years.

Enforcement

New compliance and stop notices for local authorities.

What is a higher-risk building in Wales?

The definition is in the Building Safety (Description of Higher-Risk Building) (Design and Construction Phase) (Wales) Regulations 2023. Higher-risk building work follows a gateway process: building control approval before work starts (Gateway 2), change control, mandatory occurrence reporting, a golden thread of information, and a completion certificate before occupation (Gateway 3). Decision periods are 12 weeks for a new higher-risk building and 8 weeks for work to an existing one.

The biggest structural difference is who decides. In Wales, only local authorities can oversee new higher-risk building work, working with fire and rescue authorities. The Building Safety Regulator is not the building control authority for Welsh higher-risk buildings, though it regulates registered building inspectors and registered building control approvers in Wales on behalf of the Welsh Ministers.

Work where full plans were deposited, or an initial notice was given and accepted, before 1 July 2026 continues under the previous rules. That protection can be lost if the plans are rejected or if work has not started within three years.

The occupation phase and other differences

The occupation phase is handled by separate Welsh legislation. The Building Safety (Wales) Act 2026 received Royal Assent on 27 April 2026, but only a few sections are in force.

The Act creates a regime for assessing and managing fire and structural safety risks in occupied multi-occupied residential buildings, with registration of regulated buildings that are at least 11 metres high or have at least 5 storeys. Local authorities designated by the Welsh Ministers will act as building safety authorities, and fire and rescue authorities gain new functions. Only a few sections came into force on 28 April 2026; the rest will be commenced by Welsh statutory instruments, so check the current commencement position before advising a client on occupation-phase duties.

Combustible external walls

The Building (Amendment) (Wales) Regulations 2019 require materials in external walls and specified attachments of relevant buildings to achieve class A2-s1, d0 or A1, from 13 January 2020. A relevant building has a storey at least 18m above ground and contains dwellings, an institution or rooms for residential purposes.

Where Avoice fits

Cross-border practices need to know which version of each document applies before they quote a paragraph. Most errors come from using the English text on a Welsh site.

The Avoice Regulations library holds the Welsh Approved Documents alongside the English ones, the Scottish Technical Handbooks and the Northern Ireland Technical Booklets, with AI search that says whether an answer comes from legislation or statutory guidance. In Avoice Practice, the Building Regs Tracker records how each Part is met on a project, and the CDM risk register supports the dutyholder duties that now apply in Wales.

Software can retrieve, compare and flag. The architect and building control still decide what applies to the project and whether the evidence is adequate.