What This Requirement Covers
Approved Document B, Volume 1 sets out the minimum requirements for fire detection and alarm systems in dwellings. Since October 2022, the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 have extended alarm requirements to all rented properties in England.
These requirements exist to provide early warning of fire, giving occupants time to escape safely. They apply to new-build houses, flats, and conversions, as well as existing rented accommodation.
Key Requirements
New Dwellings (Building Regulations)
- At least one smoke alarm on every storey that contains a habitable room
- A heat alarm in every kitchen
- A carbon monoxide alarm in any room containing a fixed combustion appliance (excluding gas cookers)
- All alarms must be interlinked so that activation of one triggers all others
- Alarms must be mains-powered with a battery backup (Grade D1 minimum to BS 5839-6)
- Smoke alarms should be positioned on the ceiling, at least 300 mm from any wall or light fitting
- In multi-storey dwellings, alarms on escape routes (hallways and landings) must be interlinked
Existing Rented Properties
- At least one smoke alarm on each storey of the property
- A carbon monoxide alarm in any room with a fixed combustion appliance
- Landlords must check alarms are in working order at the start of each tenancy
- The 2022 amendment extended requirements from just the private rented sector to include social housing
Flats in Purpose-Built Blocks
- Individual flats follow the same alarm provisions as houses
- Common parts require a fire detection and alarm system compliant with BS 5839-1
- For buildings over 11 metres in height, an enhanced detection system (Category L2 minimum) is typically required
- The Building Safety Act 2022 imposes additional requirements on higher-risk buildings (over 18 metres or 7 storeys)
Residential vs Commercial
Approved Document B Volume 1 covers dwellings, while Volume 2 covers non-domestic buildings. Commercial buildings require fire detection and alarm systems designed to BS 5839-1, typically at Category L or Category M depending on the building type and use. The minimum provision for offices and shops is generally a Category M system (manual call points only), while sleeping accommodation in hotels or care homes requires at least Category L1 (full automatic detection).
Exceptions and Exemptions
- Gas cookers are excluded from the carbon monoxide alarm requirement
- Existing owner-occupied properties are not legally required to comply, though it is strongly recommended
- Listed buildings may use alternative detection methods if standard installation would damage the historic fabric, subject to Building Control approval
- Where a dwelling has an open-plan layout, specific guidance in Approved Document B, Diagram 2.1 addresses detection in open-plan ground floors
Regional Variations
- England: Approved Document B and the Smoke and Carbon Monoxide Alarm Regulations 2022 apply
- Wales: Approved Document B applies but the Renting Homes (Wales) Act 2016 has its own alarm requirements for rented properties
- Scotland: Scottish Building Standards (Section 2) require interlinked alarms in all homes (including owner-occupied) since February 2022 under the Housing (Scotland) Act 1987
- Northern Ireland: Technical Booklet E covers fire safety; separate regulations govern alarm requirements in rented properties
Practical Compliance Tips
- Always install interlinked alarms in new builds; wireless interlinking is acceptable where hard-wiring is impractical
- Position smoke alarms centrally on the ceiling of circulation spaces (hallways, landings), not directly above stairs
- Use heat alarms (not smoke alarms) in kitchens to avoid nuisance activation from cooking
- Test all alarms after installation and provide the homeowner or tenant with a test record
- For flats, coordinate with the building's communal fire alarm system to avoid conflicting signals
- When upgrading an existing rental property, battery-only alarms may be used if Building Regulations approval is not required, but mains-powered alarms are strongly recommended
- Keep records of alarm installation and testing for landlord compliance documentation