LEGISLATION & STANDARDS
Approved Document B (fire safety)
A plain-English guide to Approved Document B by Daniel Storr, Founder & Managing Director · Last reviewed 11 September 2026
Approved Document B is the government’s statutory guidance on meeting the fire safety requirements of the Building Regulations in England. It is not law in itself. Instead, it is the practical guidance that shows how to meet the rules. It governs how fire doors, escape routes and compartmentation are designed and built into a building in the first place.
What Approved Document B is
Approved Document B supports Part B (fire safety) of the Building Regulations. It comes in two volumes: Volume 1 for dwellings and Volume 2 for buildings other than dwellings. It covers four areas: means of warning and escape; internal fire spread through linings and structure; external fire spread; and access and facilities for the fire and rescue service. In short, it is the fire safety rulebook for the design and construction stage. Both volumes are free to download from gov.uk.
Guidance, not law
This is an important distinction. The document is guidance, not a legal requirement in its own right. The legal duty is to meet the functional requirements of the Building Regulations. Follow the guidance and you are likely to meet them. Depart from it and you must be able to show you have satisfied the requirements another way. Its editions and amendments also change over time. So the version that matters is the one that applied when a building was built or altered. Always work from that.
Fire doors in Approved Document B
The guidance is the design stage. It sets where fire-resisting doors are needed, such as protecting stairways, corridors and compartment walls, and the performance they must achieve. Once a building is occupied, keeping those doors performing shifts to the Fire Safety Order and the responsible person. A door specified and installed correctly at construction still has to be inspected and maintained for its whole life. That is where our certified, notional or nominal guide picks up. When we install a new fire doorset, as we did at Rise School in Wimborne, the specification starts from what the guidance asks of that location.
Approved Document B: common questions
Which volume applies to a block of flats?
Volume 1 of Approved Document B covers dwellings, including blocks of flats. Volume 2 covers everything else: offices, shops, schools, care homes and so on. A building with flats above shops may need both.
What does FD30S mean?
FD30 means the door resists fire for 30 minutes. The S means it also has cold smoke seals fitted. Flat entrance doors and most doors onto escape routes need the smoke seals, so FD30S is the usual specification. FD60 doors are used where the guidance calls for 60 minutes.
Does replacing a fire door have to follow the guidance?
Yes. The new door must achieve the performance the guidance calls for in that location. Install it to the manufacturer’s instructions so it keeps its certification, and keep the certification evidence with your fire safety records. If you are unsure whether the work needs notifying, check with your local building control body.