Smoke and carbon monoxide alarm rules
One smoke alarm on each storey with living accommodation, and a carbon monoxide alarm in any room with a fixed combustion appliance. Both must work on day one of the tenancy. It is the cheapest item on the compliance list and carries penalties up to £5,000.
Gas cookers are excluded — and this trips everyone up
The carbon monoxide requirement covers rooms with a fixed combustion appliance, and gas cookers are explicitly excluded. The mistake runs both ways: some landlords fit an alarm they don't need, others assume the exclusion covers gas appliances generally. It doesn't — a gas boiler is a fixed combustion appliance and does require one.
The requirements
- Smoke alarms: at least one on each storey where there is a room used as living accommodation. Per storey, not per room — hallways and landings are the usual siting.
- Carbon monoxide alarms: in any room used as living accommodation containing a fixed combustion appliance, excluding gas cookers. Fit at head height, one to three metres from the source.
- Working on day one: every alarm must be in proper working order on the day the tenancy begins.
- Repair or replace on report: once a tenant tells you an alarm is faulty, fixing it is your duty.
From the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022, in force since 1 October 2022. Verified against GOV.UK guidance on 5 August 2026.
What changed in 2022
The 2022 amendment extended the carbon monoxide duty from solid fuel only to any fixed combustion appliance. That is what brought gas boilers into scope, and it is why guidance written before October 2022 — still widely circulating — is wrong on the central point.
Proving it, not just doing it
The duty that's hardest to evidence is the day-one one. “The alarms worked” is a claim; a dated, photographed check-in record showing each alarm tested is evidence.
A check-in report with alarms recorded as tested does that as a by-product of work you should be doing anyway. And when a tenant reports a fault later, log the report and the fix — the pair together is what demonstrates compliance to a council.
FAQ
How many smoke alarms do I need?
At least one on each storey of the property where there is a room used as living accommodation. Not one per room — one per storey. In a typical two-storey house that means one downstairs and one upstairs, usually sited in the hallway and landing, following the manufacturer's instructions.
Where do carbon monoxide alarms go?
In any room used as living accommodation that contains a fixed combustion appliance — a gas boiler, a wood burner, an open fire, an oil heater. Position them at head height, roughly one to three metres from the potential source.
Do I need a CO alarm for a gas cooker?
No. Gas cookers are explicitly excluded from the requirement. This is the single most misreported detail in this area, and it cuts both ways: landlords fit alarms they don't need, and others assume the exclusion covers gas appliances generally, which it does not. A gas boiler is a fixed combustion appliance and does need one; a gas cooker is carved out.
When did these rules change?
The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 took effect on 1 October 2022. The main change was extending the carbon monoxide requirement to any room with a fixed combustion appliance, where previously it applied only to solid fuel.
Whose job is it to test the alarms?
You must make sure every alarm is in proper working order on the day a new tenancy begins. During the tenancy, the sensible split is that the tenant tests regularly and replaces batteries, and you repair or replace any alarm they report as faulty. Put that expectation in writing at the start rather than leaving it to be discovered later.
What happens if a tenant reports a broken alarm?
You must repair or replace it. The tenant should try a battery change first, but once they've reported a genuinely faulty alarm the duty is yours. Record the report and what you did about it — that record is what demonstrates compliance if a council ever asks.
What are the penalties?
A local housing authority can serve a remedial notice, and failing to comply with it can attract a fine of up to £5,000. Alarms are also the cheapest compliance item on the entire landlord list — a few tens of pounds against a five-figure penalty and, far more importantly, a genuine safety risk.
Disclaimer: This guide is general information for UK landlords, not legal or financial advice. Law and practice change — always confirm the current position, and take advice on anything that matters.