Smoke and CO Alarm Regulations

From 2025-26 you must assume every property needs working smoke alarms on each storey and CO alarms wherever you burn fuel, with proof you tested them on move-in. Anything less is a quick route to a council fine.

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1. Core legal requirements in England

Law: Smoke and Carbon Monoxide Alarm (England) Regulations 2015, as amended by the 2022 Regulations.

You must:

• Install at least one smoke alarm on every storey of the premises where there is a room used as living accommodation.
• Install a carbon monoxide (CO) alarm in any room used as living accommodation that contains a fixed combustion appliance, excluding gas cookers.
• Fixed combustion means any fixed appliance burning gas, oil, coal, wood, biomass, etc. (boilers, gas fires, oil boilers, log burners).
• Living accommodation includes bathrooms, halls and landings, not just lounges and bedrooms.

This duty applies to most private lets (and now social landlords too), including ASTs, licences, holiday lets and temporary accommodation, unless specifically exempt.

2. Testing, types of alarm, and HMOs

Testing duty

• You must check alarms are in working order on the first day of each new tenancy.
• After that, tenants are responsible for regular testing and changing batteries, but if they report a fault you must repair or replace as soon as reasonably practicable.

Types of alarm

The Regulations do not require mains vs battery; both are acceptable if they meet British Standards.

Acceptable types:

• Sealed lithium battery alarms.
• Mains-powered alarms with battery backup (best practice).

Detection tech:

• Optical smoke alarms are preferred for most circulation areas and living spaces.
• Ionisation less common now.
• Heat alarms in kitchens to avoid false alarms.

HMO-specific requirements (beyond the minimum regs)

HMOs are covered by:

• The HMO Management Regulations,
• Licensing conditions,
• BS 5839-6:2019 fire alarm grades and categories.

Typical small HMO expectation: Grade D1, LD2 system:

• Mains-powered, interlinked smoke alarms with tamper-proof battery backup in hallways, landings, and high-risk rooms.
• Heat alarm in the kitchen, interlinked with the smokes.

Council fire safety guidance often requires more than the bare minimum Regulations; your fire risk assessment (FRA) will specify exactly what your HMO needs.

Best practice for single lets, even where not legally required:

• Use interlinked alarms throughout (hard-wired or radio).
• Fit mains-powered alarms with backup rather than cheap replaceable-battery units.

3. What the 2022 amendment actually changed

Pre-2022 (private PRS only)

• Smoke alarm on every storey with living accommodation.
• CO alarm only where there was a solid fuel appliance (eg log burner, coal fire).

From 1 October 2022 (amendment in force)

• Requirement extended to social landlords as well as private.
• CO alarm duty widened:
• Now required in any room used as living accommodation containing any fixed combustion appliance (gas, oil, solid fuel, biomass), excluding gas cookers.

So, for a typical BTL you now need CO alarms in:

• Boiler cupboard / room.
• Any room with a fixed gas fire, oil boiler, log burner, etc.

The key shift was from "solid fuel only" to "any fixed combustion appliance except gas cookers".

4. Enforcement and penalties

Enforcement

Local housing authorities enforce the smoke and CO alarm Regulations.

If the council believes you are not compliant:

• They can serve a remedial notice requiring you to fit or repair alarms within 28 days.
• If you do not comply, they must:
• Arrange for an authorised person to go in (with tenant consent) and install/repair alarms.
• They can then issue a civil penalty of up to GBP 5,000.
• Each breach can attract a separate penalty according to the council's published principles.

Note:

Councils are told to be "open and transparent" about their penalty schemes, which are usually published on their websites.

So if you skip alarms and ignore a remedial notice, you are looking at a council-arranged install plus a four-figure fine.

5. Common mistakes and what forums get wrong

Real-world mistakes

Not testing on day one: Landlords assume fitting alarms once is enough. The Regulations specifically require you to ensure they are working at the start of each new tenancy.

Missing CO alarms on gas boilers: Many landlords still think CO alarms are only for log burners. Since 2022 you need them in rooms with gas or oil boilers and other fixed combustion kit, except hobs/cookers.

Treating HMOs like single lets: Putting up one battery smoke per floor in a licensable HMO where the FRA and licence demand Grade D1, LD2 or better -- councils are now enforcing this and linking it to licence conditions.

Not replacing faulty alarms promptly: The amendment added an explicit duty to repair or replace alarms once informed they are faulty, as soon as reasonably practicable.

Forum myths

"Battery alarms are not allowed; they must all be mains." The Regulations allow battery or mains as long as they are correctly sited and working. Councils or HMO licences may push for mains-powered D1 systems, but that is over and above the baseline rules.

"CO alarm only needed in bedrooms." Wrong under current law: you need one in any living-accommodation room with a fixed combustion appliance, which includes boiler cupboards, living rooms with gas fires, and some utility rooms.

"If tenants take batteries out, it is their problem." Tenants are supposed to test and change batteries, but if they report a non-working alarm you must fix or replace it promptly. Councils look at your response, not just the tenant's behaviour.

The easiest compliance pattern is:

• Fit interlinked, mains-powered (Grade D1) smoke/heat alarms in HMOs and at least mains/best-quality sealed-battery alarms in single lets.
• Have a move-in checklist where you physically test alarms with the tenant and note it.
• Treat every boiler room or gas-fire room as CO alarm mandatory.

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