The dos and don'ts of mains powered smoke alarms and battery alarms

Most properties in the UK have battery-operated smoke alarms, but mains powered smoke alarms interlinked between floors are the most reliable method of giving early warning in case of fire and must now be installed in all new homes.

Mains-wired smoke alarms are also required in certain types of alteration and extension work. Mount them in the circulation space at every floor level:

• In loft conversions
• When adding new habitable rooms (bedrooms, kitchens, living or dining rooms) above ground floor level
• When adding a new habitable room at ground floor level that doesn’t have its own exit leading outdoors

Installing new interlinked smoke alarms can be disruptive, so think about the need for detection before you start work. Radio-linked alarms are acceptable; as long as the manufacturer can guarantee the battery back-up will last for 72 hours.

Smoke alarm DOs:

• Ensure there's at least one alarm on every storey of the dwelling
• Ensure there's an alarm within 7.5m of the door to every habitable room
• Provide a heat detector to the kitchen if it's open plan to the escape route
• Mount them 300mm away from walls and light fittings
• Ensure the electrical installation of the units meets Part P requirements
• Provide instructions to the end user

Smoke alarm DON'Ts:

• Install them above staircases where testing and maintenance is dangerous
• Site them in places where they can become very hot, cold, or subject to a lot of moisture or fumes (bathrooms, kitchens, garages - use a heat detector if need be)

Remember, there are additional requirements for large houses of two or more storeys where one of those storeys exceeds 200m², so bear this in mind when working on footballers' mansions! If in any doubt, contact your local authority building control team to discuss.

Further information about fire safety

• View a diagram showing where to place smoke alarms and heat alarms
• Download the SCA Guidance on Smoke Control to Common Escape Routes in Apartment Buildings (Flats and Maisonettes)
• Read the Building Regulations Part B Approved Document on Fire Safety

Also view: How to protect residents from carbon monoxide poisoning

Please Note: Every care was taken to ensure the information was correct at the time of publication. Any written guidance provided does not replace the user’s professional judgement. It is the responsibility of the dutyholder or person carrying out the work to ensure compliance with relevant building regulations or applicable technical standards.

^{This article was updated on 28 March 2022}