How many smoke alarms do I need and where should they go?

Glossary · Alarms, lighting and home installs

How smoke alarm numbers and positions work

The government’s fire safety advice is to fit at least one smoke alarm on every level of your home.^{[1]Home Office, Fire safety in the home} Electrical Safety First gives the same minimum of one smoke or heat alarm per floor and adds that you should fit enough alarms to cover all the areas where a fire could start.^{[4]Electrical Safety First, Electrical safety advice for the bathroom}

The best position is on the ceiling, in the middle of a room, and on the hallway and landing so you can hear an alarm throughout the home.^{[1]Home Office, Fire safety in the home} Smoke rises before it spreads out, so a central ceiling position lets it reach the sensor sooner than any other spot.^{[3]Aico, Where to position smoke alarms and heat alarms}

For landlords in England the rule is legal. At least one smoke alarm must be equipped on each storey with a room used wholly or partly as living accommodation. The guidance says a hall or landing counts as a room, and a mezzanine floor does not count as a storey. The regulations do not say where the alarm must go, but in general it should be fixed to the ceiling in a circulation space such as a hall or landing.^{[2]Department for Levelling Up, Housing and Communities, Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022: guidance for landlords and tenants} Our page on BS 5839-6 explains the fuller standard.

Where to fit each alarm

The kitchen and bathroom advice comes from the government, which says not to put alarms in or near kitchens or bathrooms and that heat alarms can detect fires in kitchens.^{[1]Home Office, Fire safety in the home} The bedroom distance and the heat alarm reasoning come from Aico, which also says alarms should be about 300mm from walls, light fittings or obstructions to airflow. On a sloping ceiling Aico says a smoke alarm sits a maximum of 600mm vertically down from the apex, and a heat alarm 150mm.^{[3]Aico, Where to position smoke alarms and heat alarms}

Aico adds that a heat alarm in a kitchen triggers once the temperature reaches 58 degrees Celsius, and that it should not be used in other rooms where a smoke alarm gives a faster response.^{[3]Aico, Where to position smoke alarms and heat alarms} For homes with a gas boiler or log burner, a separate carbon monoxide alarm is needed. Landlords must fit one in any room used as living accommodation that has a fixed combustion appliance, other than a gas cooker. See our carbon monoxide detector service.^{[2]Department for Levelling Up, Housing and Communities, Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022: guidance for landlords and tenants}

Testing and looking after alarms

Testing is a householder job. The government says to test your alarms at least monthly by pressing the button until the alarm sounds. If it does not sound, you need to replace the battery. Vacuum your alarms every six months to remove dust. If a ten-year alarm reaches the end of its life, replace the whole alarm.^{[1]Home Office, Fire safety in the home}

If an alarm goes off by mistake, never disconnect it or take the batteries out.^{[1]Home Office, Fire safety in the home} Mains-powered alarms are powered by the home supply with a back-up battery, and they need to be installed by a qualified electrician.^{[1]Home Office, Fire safety in the home} That applies to any new mains-wired alarm. Our smoke alarm and fire safety service fits mains-wired, interlinked alarms in hallways and landings with a heat alarm in the kitchen.^{[5]Martin Day Electricians, Smoke and fire alarm installation in Leeds}

Example

Daniel owns a three-storey terrace in Headingley. The ground floor, the first floor and an attic bedroom are all in use. He needs at least one smoke alarm on each of the three levels.^{[1]Home Office, Fire safety in the home} He places one on the ceiling of the ground floor hall and one on each landing.

He adds a smoke alarm in the main living room, a heat alarm in the kitchen and checks the nearest alarm is within 3 metres of each bedroom door.^{[3]Aico, Where to position smoke alarms and heat alarms} He tests each alarm on the first of the month by pressing the button. When he wants them interlinked and mains-wired, he books a registered electrician.

What people get wrong

Many people put a smoke alarm in the kitchen because that is where fires start. It is the wrong place for a smoke alarm. Cooking smoke sets it off, people take the battery out, and then there is no alarm at all. The government advises against alarms in or near kitchens and bathrooms, and points to heat alarms for kitchens.

The other common mistake is stopping at the legal minimum. One alarm per storey is the floor, not the target. Electrical Safety First advises enough alarms to cover every area where a fire could start.^{[4]Electrical Safety First, Electrical safety advice for the bathroom}

The bottom line

Fit at least one smoke alarm on every level, on the ceiling, in the hallway and landing, and keep them out of kitchens and bathrooms. Landlords in England have a legal duty to equip every storey and to fix faulty alarms. Test monthly yourself, and use a registered electrician for anything mains-powered. A heat alarm covers the kitchen, and a carbon monoxide alarm covers rooms with a fixed fuel-burning appliance.