How many smoke alarms does a rental need?

At least one smoke alarm on every storey of the property that has a room used as living accommodation. A three-storey house therefore needs at least three.

Where do carbon monoxide alarms need to go?

A carbon monoxide alarm is required in any room used as living accommodation that contains a fixed combustion appliance — such as a gas boiler, gas fire, oil boiler or wood-burning stove — excluding gas cookers.

Does the landlord have to check the alarms?

Yes. The landlord must make sure alarms are working at the start of each new tenancy, and must repair or replace any alarm reported as faulty during the tenancy, including replacing batteries.

What is the penalty for not having alarms?

A local authority can serve a remedial notice and, if it isn't complied with, impose a civil penalty of up to £5,000.

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Landlord compliance

Smoke and carbon monoxide alarms: the landlord rules

It's one of the cheapest legal duties a landlord has — and one of the easiest to fail on a technicality. Here's exactly how many alarms you need, where, and what you must do.

Written for UK landlords (England) · Last updated August 2026 · 5 min read

The quick answer: Fit at least one smoke alarm on every storey with living space, and a carbon monoxide alarm in any room with a fixed combustion appliance (boiler, gas fire, wood burner — not gas cookers). Make sure they work on day one of each tenancy, and repair or replace any reported faulty — batteries included. Fail and the council can fine you up to £5,000.

What the law requires

Under the Smoke and Carbon Monoxide Alarm regulations for England, every private rental must have working alarms in the right places. The rules were tightened in 2022 to cover more appliances and to put the repair duty firmly on the landlord — so older assumptions ("the tenant sorts the batteries") no longer hold.

Where the alarms go

Smoke alarms — at least one on every storey that has a room used as living accommodation. A three-storey house needs at least three; a flat over one floor needs at least one.

Carbon monoxide alarms — one in any room with a fixed combustion appliance — a gas boiler, gas fire, oil-fired boiler or wood-burning stove. Gas cookers are excluded.

It's good practice (and often required by newer standards) to go beyond the minimum — for example an alarm near sleeping areas — but the above is the legal floor.

Your ongoing duties

Check they work on the first day of each new tenancy — and keep a dated, signed record that you did.
Repair or replace any alarm the tenant reports as faulty during the tenancy — this includes replacing batteries.
Position and maintain alarms per the manufacturer's instructions.

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The penalty for getting it wrong

Up to £5,000. If you don't meet the alarm rules, the local authority can serve a remedial notice. Ignore it and they can impose a civil penalty of up to £5,000 — a lot of money for something a £20 alarm and a five-minute check would have prevented. And beyond the fine, this is the duty most directly tied to a tenant's life.

Your alarm checklist

Fit a smoke alarm on every storey with living space.
Fit a CO alarm in every room with a fixed combustion appliance (not gas cookers).
Test them on the first day of each tenancy and record it.
Fix or replace any faulty alarm the tenant reports — promptly.
Replace alarms per their expiry (most last around 10 years).

Frequently asked questions

Do the alarms have to be mains-wired?

The regulations don't specify the type — battery or mains — so either can satisfy the law, though many landlords prefer sealed 10-year or mains-linked alarms for reliability. Newer building standards for some properties may require more.

Whose job is it to test alarms during the tenancy?

Day-to-day testing is sensibly the tenant's routine, but if they report a fault, the duty to repair or replace sits with you as the landlord.

Do I need a heat alarm in the kitchen?

Not under these specific regulations, but heat alarms in kitchens are good practice and may be required by other standards or in HMOs. Check your HMO conditions if relevant.

Does this apply to HMOs too?

Yes, and HMOs often have additional, stricter fire-safety requirements on top — including fire doors and escape routes as part of licensing.

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