What Is Part B? — Fire Safety Regulations

For a typical two-storey house, Part B requires: interlinked smoke alarms on every storey (mains-wired with battery backup since June 2022), 30-minute fire resistance between the garage and habitable rooms, and adequate means of escape from every habitable room. Under AD B Vol 1 para 2.2, where no floor is more than 4.5m above ground, each habitable room other than the kitchen needs either an emergency escape window or external door, or direct access to a protected stairway. Fire doors are not required on that escape route in a two-storey house.

Fire doorsets are required between an integral or attached garage and the house (E 30 Sa, sold as FD30S, per AD B Vol 1 Table C1 item 11a), and on the doorsets enclosing a protected stairway, including the protected route created by a loft conversion (para 2.21b). In a single-family house those stairway doorsets are minimum E 20 only (Table C1 item 11b), with no cold smoke seal and no self-closing device: Appendix C5 requires a self-closer on the garage door and flat entrance doors, not on fire doorsets within a dwellinghouse. FD20 doorsets are no longer certified as products, so an FD30 door is what you buy to satisfy an E 20 requirement.

Compartmentation divides a building into fire-resisting compartments to limit fire spread. In domestic buildings, this mainly applies to party walls (providing 60-minute fire resistance between attached houses), floor/ceiling assemblies in flats (60-minute between dwellings), and the garage-to-house separation (30-minute). All service penetrations through compartment walls and floors must be fire-stopped.

A loft conversion creating a new storey above 4.5m requires the full escape route to be addressed (AD B Vol 1 para 2.21): a protected stairway from the loft to the final exit with fire-resisting doors (minimum E20/FD20) and partitions (minimum REI 30), interlinked smoke detection on all levels, and fire separation between the loft and the rest of the building. Where that protected stairway is provided, no escape window is required in the loft room itself. An escape window (minimum 0.33 m², at least 450 mm wide and high, bottom of the openable area no more than 1100 mm above floor level) is only required under the para 2.23 open-plan alternative, where sprinklers protect the open floor and the window sits on the first storey rather than in the loft room.

Yes. Following the Grenfell Tower tragedy in 2017 and the Hackitt Review, significant changes have been made. The Building Safety Act 2022 introduced a new Building Safety Regulator for higher-risk buildings (over 18 metres or 7 storeys). Combustible cladding materials are banned on buildings over 11 metres. A new gateway approval process applies to high-rise residential buildings, with stricter documentation requirements at design, construction, and completion stages.