Smoke and Carbon Monoxide Alarms: What UK Homeowners Must Know

Smoke and carbon monoxide alarms are among the most cost-effective safety measures available for any home. They are also subject to specific legal requirements in the UK, particularly for landlords. But understanding the rules is useful for owner-occupiers too.

The Legal Position

The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 (updated in 2022) require private sector landlords in England to:

• Install at least one smoke alarm on every storey of their property used as living accommodation
• Install a carbon monoxide alarm in any room used as living accommodation that contains a fixed combustion appliance (such as a gas boiler, wood-burning stove, or open fire). But not gas cookers
• Ensure all alarms are in working order at the start of each new tenancy

Scotland, Wales, and Northern Ireland have their own regulations. In Scotland, the Tolerable Standard regulations (2022) are significantly more demanding, requiring interlinked alarms in all rooms. The Scottish Government guidance is worth reading if you are a landlord or homeowner in Scotland.

While owner-occupiers in England are not legally required to install alarms, the Building Regulations require smoke alarms in new builds and major renovations. More importantly, the absence of working alarms in a house fire is consistently identified as a factor in fatalities.

Smoke Alarms

Types

There are two main types of smoke alarm:

• Ionisation alarms detect the fast-flaming fires typical of burning paper and wood. They are less sensitive to slow, smouldering fires and produce more false alarms from cooking.
• Optical (photoelectric) alarms are better at detecting slow, smouldering fires (the type most likely to occur at night, often from furniture or wiring). They are less prone to nuisance alarms from cooking.

The London Fire Brigade recommends optical alarms as the first choice, or a combination of both types for maximum protection.

Placement

• Install on the ceiling, as close to the centre of the room as possible
• At minimum, place one on every floor, hallways and landings are good positions because they cover escape routes
• Keep alarms at least 30cm from any wall or light fitting
• Do not install in kitchens or bathrooms where steam and cooking fumes cause false alarms

Interconnected Alarms

Interconnected alarms (wired or wireless) trigger all alarms in the home simultaneously when one detects smoke. This is strongly recommended in two-storey or larger homes, where an alarm in the hallway may not be audible from an upstairs bedroom with the door closed.

Carbon Monoxide Alarms

Carbon monoxide (CO) is produced when fuels such as gas, oil, coal, or wood do not burn completely. It is colourless and odourless, which makes it impossible to detect without an alarm.

According to NHS figures, around 60 people die from accidental CO poisoning in England and Wales each year, with many more requiring hospital treatment.

Where CO Alarms Are Required

Any room containing a fixed combustion appliance needs a CO alarm. This includes:

• Gas boilers (including combi boilers)
• Gas fires
• Wood-burning stoves and open fireplaces
• Oil boilers
• LPG appliances

Gas cookers are currently exempt from the regulations in England, though many safety organisations recommend installing a CO alarm in the kitchen regardless.

Placement

CO alarms should be:

• Placed at head height, on a wall or shelf, CO is similar in weight to air and distributes evenly
• Within 1 to 3 metres of the potential source
• Audible from the bedroom, or a separate alarm should be installed in the sleeping area

What To Do If Your CO Alarm Sounds

If a CO alarm sounds:

1. Get everyone out of the property immediately
2. Do not go back inside
3. Call the Gas Emergency Service on 0800 111 999 (available 24 hours)
4. Do not re-enter until emergency services say it is safe

Testing and Maintenance

Both smoke and CO alarms should be tested monthly by pressing the test button. Alarms with replaceable batteries should have the batteries replaced annually, a common practice is to do this when the clocks change in October.

Most smoke alarms have a lifespan of 10 years and CO alarms 5 to 7 years. Check the manufacturer's guidance, alarms past their expiry date should be replaced regardless of whether they appear to work.

Recommended Specification

For an average three-bedroom UK home, a reasonable setup would include:

• Optical smoke alarms: ground floor hallway, first floor landing, living room
• CO alarm: room containing the boiler, and any rooms with open fires or stoves
• All alarms interconnected where possible

The Fire Kills campaign run by the UK Government provides free, up-to-date advice on home fire safety.

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