How to Fit a Smoke Alarm: Positions and Types in the UK
Where to put smoke and heat alarms in a UK home, battery versus mains types, how to fix them securely, test them and when to ask an electrician.
A working smoke alarm gives you precious extra seconds in a fire. Fitting one is a quick job, and getting the type and position right matters far more than the screwing. This guide covers how to choose, where to put alarms and how to fix them, with a note on when electrical work is involved.
Choose the right type
- Battery-powered with a sealed long-life battery. Easy to fit with two screws and no wiring. They last for several years before the unit needs replacing.
- Replaceable-battery alarms. Cheaper, but need new batteries and regular checks.
- Mains-powered alarms, often with battery backup. Wired into the house electrics and usually interlinked, so one triggers all.
- Radio-interlinked battery alarms. Wireless alarms that talk to each other without wiring.
- Heat alarms. For kitchens, where smoke alarms would trigger from cooking. They respond to a rise in temperature.
- Carbon monoxide alarms. Separate devices, essential near fuel-burning appliances. A smoke alarm does not detect CO.
Look for an alarm that conforms to the relevant British Standard and carries a kitemark.
Where to put them
In general, guidance recommends:
- At least one smoke alarm on every storey of the home
- In the hallway and landing, on the escape route
- A heat alarm in the kitchen, not a smoke alarm
- On the ceiling, ideally in the middle of the room or hall, and at least 30 cm from walls and light fittings
- Away from bathrooms, shower rooms and cooking areas that can create steam or fumes
- In rooms where people sleep, if the bedroom doors are closed and you want earlier warning, though bedroom regulations in rented homes have specific rules
Rules for landlords differ by nation, and may specify alarms on every floor and CO alarms in rooms with solid fuel appliances. See landlord repair responsibilities for context.
Fitting a battery alarm
- Hold the mounting plate against the ceiling and mark the screw holes. Check that there are no cables or pipes above; see checking for pipes and cables before drilling.
- Drill small holes and insert plugs, if the ceiling is solid. On plasterboard, use suitable plasterboard fixings.
- Screw the plate to the ceiling.
- Insert the battery, or activate a sealed unit, and attach the alarm to the plate by twisting.
- Press the test button and confirm the alarm sounds.
- Note the date. Many alarms have a replacement date, typically up to ten years.
Fitting radio-interlinked alarms
Follow the manufacturer's instructions to pair units. Usually you fit each alarm and then press a button on each in sequence to link them. Test by pressing the test button on one and confirming that all sound.
Mains alarms: electrical work
Replacing an existing mains alarm with the same type of alarm on the same circuit is a like-for-like job. Adding new mains alarms, new wiring or new circuits is electrical work and is usually notifiable in some circumstances. A registered electrician should install or modify mains systems. See can a handyman do electrical work?.
Testing and maintenance
- Test weekly or monthly by pressing the button.
- Replace batteries when the alarm chirps, or annually for replaceable types.
- Vacuum dust from the alarm gently, to avoid false alarms.
- Replace the alarm at the end of its life, as marked on the unit.
- Do not paint over alarms or cover them.
- Never remove a battery from an alarm to stop false alarms from cooking; relocate it if it is poorly placed.
Make an escape plan
An alarm is only part of fire safety. Plan escape routes, keep exits clear and agree where to meet outside. Do not tackle a fire yourself.
Costs and booking help
Fitting a battery alarm is a quick handyman task, often combined with other jobs; see how to save money by batching handyman jobs. On Compito, you can send a request with your postcode and the number of alarms, compare offers from ID-verified local providers, message them with questions and pay online when you accept.
A worked example: a two-storey house
For a typical two-storey home, a sensible minimum is a smoke alarm on the hall and one on the landing, a heat alarm in the kitchen and a carbon monoxide alarm near any boiler or fuel-burning appliance. That is four devices, and if the alarms are interlinked wireless units, you can fit them in an hour or two with a drill and a screwdriver. Testing takes a further few minutes.
Common placement mistakes
- Putting an alarm too close to the bathroom door, where steam sets it off.
- Fitting it on a wall near the ceiling corner, where air movement is poor.
- Placing it in a loft or garage, where temperature extremes cause false alarms or failures.
- Mounting it on a sloping ceiling without checking the manufacturer's advice.
- Fitting on a surface that vibrates, such as a thin plasterboard panel with no backing.
Special circumstances
- Older people or anyone hard of hearing. Consider alarms with strobe lights or vibrating pads. Ask your local fire and rescue service for advice, as some offer free home safety visits.
- Flats. Follow the building's fire strategy, and do not tamper with communal alarms.
- Rented homes. Landlords usually have duties to provide working alarms, so tenants should ask in writing rather than fitting their own unapproved wiring.
Keep the paperwork
Keep the instruction leaflet and note the installation date and batteries on a label inside a cupboard. It makes replacement day easy to remember. For more on testing routines, see the smoke alarm testing schedule.
Frequently asked questions
Can I put a smoke alarm in the kitchen?
It is better to use a heat alarm there, as a smoke alarm tends to trigger from cooking.
How often should I replace smoke alarms?
Typically every ten years, or according to the date on the unit. Replace sooner if it fails testing.
Do I need both smoke and carbon monoxide alarms?
They protect against different dangers. If you have any fuel-burning appliance, a CO alarm is strongly recommended in addition to smoke alarms.