Finance Editor, Kael Tripton Ltd - LBS MBA - Verified against FCA Handbook: 14 June 2026
Quick answer
Part B (Approved Document B, updated December 2022) covers fire safety in buildings -- smoke alarms, fire resistance, escape routes and cladding. Key thresholds: 11 metres requires sprinklers in new residential buildings; 18 metres triggers the Building Safety Act 2022 higher-risk regime and Building Safety Regulator oversight. Both volumes updated post-Grenfell.
What Does Part B of the Building Regulations Cover?
Direct answer
What does Part B of the Building Regulations require for fire safety?
Part B (Approved Document B, updated December 2022) requires: interlinked smoke alarms in dwellings, appropriate fire resistance periods for load-bearing elements, protected escape routes, restricted external cladding materials, sprinklers in new residential buildings over 11 metres, and registration with the Building Safety Regulator for buildings over 18 metres under the Building Safety Act 2022.
Identify which volume of Part B applies
Volume 1 for dwellings, Volume 2 for all other buildings. Check the current 2022 edition at gov.uk/government/publications/fire-safety-approved-document-b.
Check smoke and CO alarm requirements
New dwellings and rented properties require interlinked smoke alarms and CO alarms in specified locations.
Assess fire resistance requirements
For load-bearing elements, check the required fire resistance period based on the building's height and purpose of use table in Approved Document B.
For buildings over 11 metres -- check sprinkler requirement
New residential buildings over 11 metres in England require sprinkler systems throughout.
For buildings over 18 metres -- register with Building Safety Regulator
Higher-risk buildings must be registered with the BSR and comply with the new dutyholder regime under the Building Safety Act 2022.
| Building height | Key Part B requirements | Additional regime |
|---|---|---|
| Up to 11m | Smoke alarms, CO alarms, 30-min fire resistance (dwellings), escape routes | Standard Building Control |
| Over 11m | All above + sprinklers throughout new residential buildings | Standard Building Control |
| Over 18m (7+ storeys) | All above + enhanced cladding rules, no private approved inspectors | Building Safety Act 2022 -- BSR oversight |
| Over 30m | All above + second staircase (new buildings from 2026) | Building Safety Regulator |
Related KT guides
Frequently Asked Questions
What is Part B of the Building Regulations?
Part B of the Building Regulations (Approved Document B, volumes 1 and 2) covers fire safety in buildings. It sets minimum standards for: means of warning and escape in case of fire, internal fire spread (linings and structure), external fire spread, and access and facilities for the fire service. Approved Document B was significantly updated in December 2022 following the Grenfell Tower fire and the Hackitt Review recommendations. Volume 1 covers dwellings (houses, flats, student accommodation). Volume 2 covers buildings other than dwellings.
What smoke alarms are required under Part B?
Under Part B for new dwellings, interlinked smoke alarms must be installed: on every storey of the dwelling if there is a room used or intended to be used as a living room, in every circulation area (hall, landing), and in all principal habitable rooms. Carbon monoxide alarms must be installed in rooms containing a fixed combustion appliance (boiler, fire, log burner). From October 2022, the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 also require CO alarms in all rooms with a fixed combustion appliance in rented properties.
What are the fire resistance requirements under Part B?
Part B requires building elements to resist the spread of fire for a specified period. The required fire resistance period depends on the building's height, use and occupancy. For dwellings: load-bearing elements must achieve 30 minutes fire resistance for up to 5 storeys and 60 minutes above 5 storeys. For buildings over 11 metres (the threshold introduced after Grenfell), significantly enhanced requirements apply including prohibition of certain cladding materials.
What are the 11-metre and 18-metre height thresholds under Part B?
Approved Document B and the Building Safety Act 2022 introduce specific thresholds for high-rise residential buildings. The 11-metre threshold (approximately 4 storeys): requires sprinklers in all new residential buildings over 11 metres in England. The 18-metre threshold (approximately 7 storeys): buildings over 18 metres are classified as higher-risk buildings under the Building Safety Act 2022 and subject to the new building safety regime including mandatory registration with the Building Safety Regulator.
How does Part B relate to the Building Safety Act 2022?
The Building Safety Act 2022 created a new regulatory regime for higher-risk buildings (18 metres or 7 storeys and above). The Act established the Building Safety Regulator (BSR), a new function within the HSE, responsible for overseeing the design, construction and occupation of higher-risk buildings. The BSR also became the Building Control Authority for higher-risk buildings -- private approved inspectors can no longer certify new higher-risk buildings. Part B must be read alongside the Building Safety Act 2022 for higher-risk buildings.
Primary sources
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