Comprehensive guide to fire alarm requirements in UK new build houses

This guide covers the BS 5839-6 smoke alarm new build regulations, minimum alarm numbers, placement rules, interlinking requirements, and the importance of heat alarm kitchen regulations. It also explains devolved nation variations, power supply types, and why going beyond the minimum can enhance safety and long-term reliability.

Regulatory framework for new build fire alarms

In the UK, fire alarm requirements for new builds are shaped by both Building Regulations and BS 5839-6 — the British Standard for domestic fire detection and alarm systems.

England & Wales

Building Regulations Approved Document B (Fire Safety) states that all new dwellings must have:

• Smoke alarms on each storey.
• Smoke alarms in circulation spaces (e.g. hallways and landings).
• Heat alarms in kitchens (where open-plan, often in conjunction with additional smoke alarms).
• Part J requires carbon monoxide (CO) alarms in any room with a solid fuel-burning appliance.
• For multi-storey new builds, alarms must be interlinked.

Scotland

Since February 2022, all homes including new builds must have:

• One smoke alarm in the living room (or the most frequently used room).
• One smoke alarm in every hallway or landing.
• One heat alarm in the kitchen.
• All alarms interlinked (either hard-wired or wireless).
• CO alarms in any room with a fuel-burning appliance or flue.

Northern Ireland

Building Regulations Technical Booklet E requires:

• Mains-powered smoke alarms with battery backup on every floor.
• Heat alarms in kitchens.
• CO alarms for rooms with solid fuel appliances.

Tip for installers: BS 5839-6 is not itself law, but it is referenced as best practice in all UK nations and is the benchmark for Building Control approval.

Minimum smoke alarm quantities & placement

Under BS 5839-6 smoke alarm new build guidance for Category LD2 systems, alarms must be installed in circulation spaces and high-risk rooms.

Storey-level coverage

Number of smoke alarms per storey new build: At least one smoke alarm is required for every storey used for living purposes, including basements and loft conversions.

Habitable and circulation zones

Install smoke alarms:

• In hallways and landings.
• In main living areas such as lounges and family rooms.
• Outside bedrooms for early warning at night.

Heat alarms should be installed in kitchens to prevent nuisance alarms from cooking.

Positioning rules:

• Ceiling-mounted, at least 300 mm away from walls or light fittings.
• Ideally located centrally in the room or space for optimal detection.

Grade D (D1, D2) alarm systems explained

In domestic new builds, alarms must meet Grade D1 or D2 under BS 5839-6.

Grade D1 system new build: Mains-powered alarms with a tamper-proof, sealed, rechargeable battery backup (10-year lifespan).

Grade D2 system new build: Mains-powered alarms with user-replaceable battery backup.

Most new build projects opt for Grade D1 for reduced maintenance and compliance longevity.

LD2 (common in new builds): Smoke alarms in circulation areas and high-risk rooms (e.g. living rooms), plus heat alarms in kitchens.

LD3 (minimum in some small dwellings): Smoke alarms in circulation areas only, not recommended where LD2 can be achieved.

Heat alarms in kitchens for new builds

Heat alarm kitchen regulations require:

• A fixed, ceiling-mounted heat alarm in the kitchen.
• Siting at least 300 mm from walls and fittings, away from dead air spaces.
• Avoiding placement too close to ovens or hobs to reduce nuisance activations.

Why they’re important:

• Optical smoke alarms can trigger falsely from cooking smoke or steam.
• Heat alarms detect a rapid rise in temperature, ensuring reliable activation only during actual fire conditions.

Interlinking & power supply requirements

Why interlinked smoke alarms matter

If one alarm detects danger, all connected alarms sound simultaneously critical for alerting occupants throughout a property.

Regulate interlinked alarms new homes requirements differ slightly by region, but all new multi-storey dwellings in the UK require them.

Power options

Mains-powered: Preferred for new builds; connect to a local lighting circuit with battery backup.

Battery-only: Sealed, long-life lithium battery units are typically used for retrofits, not new builds.

Interlink types

Hard-wired: Reliable and Building Control-friendly.

Wireless (radio-link): Ideal where wiring routes are impractical.

Beyond minimum best practice & added protection

While regulations set a baseline, many trade professionals choose to exceed them to offer clients greater safety and value.

Upgrade options:

• Multi-sensor alarms: Combine optical and heat sensors for faster, more reliable detection.
• Smart alarms: Wi-Fi connectivity for remote alerts and status checks.
• CO + Smoke combo units: Reduce the number of devices while maintaining safety.

Going beyond minimum compliance can be a selling point for your projects, especially for landlords and housing developers seeking long-term peace of mind.