Approved Document B — Fire safety (Building Regulations, England)

What it is for

Approved Document B is the statutory guidance supporting Part B of the Building Regulations in England. It sets out ways of meeting the functional requirements for fire safety in building work: means of warning and escape, internal and external fire spread, and access and facilities for the fire service.

It is guidance, not regulation. The Building Regulations state functional requirements; the Approved Document describes one way — the prescriptive way — of satisfying them. Following it is not compulsory, and other routes are available, but a departure has to be justified rather than simply asserted.

Scope and typical application

Two volumes. Volume 1 covers dwellings; Volume 2 covers buildings other than dwellings. It applies in England only — Wales, Scotland and Northern Ireland have their own documents, and material written for one nation should not be applied to another without checking.

The Approved Document governs building work: new construction, material alterations and material changes of use. It is not, in itself, the standard against which an occupied building's ongoing fire safety management is judged — that is the territory of the Fire Safety Order and the fire risk assessment that sits under it.

It nonetheless matters a great deal to assessment work, for one practical reason. It establishes what a building should have been given when it was built or altered. When an assessment finds that a compartment wall has been breached or a protected route compromised, the Approved Document current at the time of the work is usually where the original expectation came from.

How it relates to legal duty

The duty comes from the Building Regulations, made under the Building Act 1984. Compliance may be demonstrated by following the Approved Document or by another route that meets the functional requirements — BS 9999 and BS 9991 being the recognised alternatives. Where the Approved Document has been followed, that tends to be treated as evidence of compliance; where it has not, the burden of demonstrating compliance sits with the person carrying out the work.

For higher-risk buildings in England, the Building Safety Act 2022 regime adds a further layer of duty and gateway approval that the Approved Document does not displace.

Amendments and what is currently in force

The 2019 edition has been amended repeatedly, and the amendment position is more involved than a single edition date suggests.

In force now: the 2019 edition incorporating the May 2020, June 2022 and 2025 amendment sets. The 2025 amendments took effect on 2 March 2025, with transitional provisions preserving the earlier position for work notified before that date and sufficiently progressed within the permitted window.

Published but not yet in force: a further amendment set takes effect on 30 September 2026, with an eighteen-month transitional period, and another on 2 September 2029, with a six-month transitional period. The consolidated PDF published on gov.uk shows all of this together, which is convenient but does mean the document you download contains text that does not yet apply. Anyone using it needs to be clear which column they are reading.

Status and currency

Current. The gov.uk publication page was last updated on 11 March 2025. Because the amendment and transitional position changes over time, the operative question for any particular project is not which edition is current but which amendment set applied when the work was notified.