Smoke and carbon monoxide alarms in rental properties: the 2026 rules

In England, a rented home needs a smoke alarm on each storey used as living accommodation and a carbon monoxide alarm in any room with a fixed combustion appliance other than a gas cooker. Test them on the first day of each new tenancy and repair or replace a faulty one once you're told. Ignore a council remedial notice and the penalty can reach £5,000.

The legal framework

The rules come from two pieces of legislation. The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 first introduced the requirement for smoke alarms on every storey and carbon monoxide alarms in rooms with solid fuel appliances. The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 significantly expanded the carbon monoxide alarm requirement to cover all rooms with fixed combustion appliances, including gas and oil appliances.

These regulations apply to most residential tenancies in England, including assured shorthold tenancies (now simply assured tenancies under the Renters' Rights Act 2025) and licences to occupy. They do not currently apply to lodger arrangements where the landlord lives in the same property, though installing alarms in these situations is still strongly advisable.

They also do not apply to an HMO that needs a licence under Part 2 of the Housing Act 2004, or a house that needs a selective licence under Part 3. For those properties, the alarm duties come from the licence conditions instead: a smoke alarm on each storey used as living accommodation, and a carbon monoxide alarm in any room with a fixed combustion appliance other than a gas cooker. An HMO that does not need a licence is covered by the regulations.

Where smoke alarms must be installed

You must install at least one smoke alarm on every storey of the property that is used as living accommodation. "Living accommodation" includes bedrooms, living rooms, kitchens, hallways, and landings. A basement or loft conversion that is used as a habitable room counts as a separate storey and requires its own alarm.

Positioning smoke alarms

The regulations require an alarm on each storey but do not specify exact positioning. However, following manufacturer guidance and British Standard BS 5839-6 is strongly recommended. As a general rule:

• Hallways and landings are the best locations, as they cover escape routes and detect smoke spreading between rooms.
• Avoid kitchens for smoke alarms, as cooking fumes cause frequent false alarms. If the kitchen opens directly onto a hallway, position the alarm as far from the kitchen door as practical, or use a heat alarm in the kitchen instead.
• Mount on the ceiling, at least 300mm from any wall or light fitting. Smoke rises, so ceiling-mounted alarms detect it fastest.
• Avoid positioning near bathrooms where steam could trigger false alarms.
• In rooms with pitched ceilings, BS 5839-6 says to mount the alarm at the apex or within 600mm below it.

While the minimum legal requirement is one alarm per storey, installing alarms in every bedroom and living room provides significantly better protection. For HMOs, additional requirements may apply under local licensing conditions, so check our guide on HMO compliance for details.

Where carbon monoxide alarms must be installed

Since the 2022 amendment, a carbon monoxide alarm must be installed in any room that contains a fixed combustion appliance. This includes:

• Gas boilers: the most common requirement. If the boiler is in a kitchen, utility room, or cupboard, the alarm goes in that space.
• Gas fires: any room with a gas fire needs a carbon monoxide alarm.
• Oil-fired boilers and heaters: covered since the 2022 amendment.
• Wood-burning stoves and open fires: these were covered by the original 2015 regulations.
• Coal fires: any solid fuel appliance.

The one exception is gas cookers. The regulations explicitly exclude gas cookers from the carbon monoxide alarm requirement. However, installing a carbon monoxide alarm in a kitchen with a gas cooker is still good practice, as any gas appliance can produce carbon monoxide if it malfunctions.

Positioning carbon monoxide alarms

Carbon monoxide is roughly the same density as air and mixes evenly throughout a room, so positioning is less critical than for smoke alarms. However, best practice is:

• Install at head height, either on a wall or on the ceiling.
• Position between 1 and 3 metres horizontally from the combustion appliance.
• Do not place directly above the appliance, where heat could damage the alarm or affect its readings.
• Do not place behind furniture, curtains, or in enclosed spaces where air circulation is restricted.
• If the boiler is in a cupboard, the alarm should be placed in the room outside the cupboard rather than inside it (unless the cupboard is large enough for the alarm to function properly).

Do the rules differ across the UK?

Yes, significantly. The regulations described above apply to England. If you let property elsewhere in the UK, the baseline is different, and in Scotland and Wales it is stricter:

• Scotland: since February 2022, every home (including owner-occupied homes) must have interlinked smoke alarms: one in the living room, one in every hallway and landing, plus a heat alarm in the kitchen. A carbon monoxide alarm is required in every room with a fixed combustion appliance or a flue, apart from appliances used only for cooking. For rentals this forms part of the Repairing Standard. See the Scottish Government guidance.
• Wales: under the Renting Homes (Wales) Act 2016, rented homes must have mains-powered, interlinked smoke alarms on every storey and carbon monoxide alarms in rooms with gas, oil, or solid fuel appliances, as part of the fitness for human habitation requirements. See Welsh Government guidance.
• Northern Ireland: the Private Tenancies Act (Northern Ireland) 2022 introduced smoke, heat, and carbon monoxide alarm requirements for private tenancies. See nidirect guidance.

If your portfolio spans nations, the practical approach is to meet the strictest standard you are subject to. Mains-powered, interlinked smoke alarms on every storey and in every hallway and landing, plus a smoke alarm in the living room and a heat alarm in the kitchen, meet the smoke and heat alarm rules in England, Wales and Scotland. Carbon monoxide rules differ between the nations, so check them for each home.

Whose job is it during the tenancy?

A common point of confusion. The split works like this in England:

• Landlord, at tenancy start: ensure every required alarm is installed and proven working on day one, and keep a record of that test.
• Tenant, during the tenancy: government guidance expects tenants to test alarms regularly (monthly is the usual advice), replace user-replaceable batteries, and report faults.
• Landlord, when informed: repair or replace a faulty alarm as soon as reasonably practicable after the tenant reports it. Since the 2022 amendment this is an explicit legal duty.

Put this split in writing. A line in the tenancy agreement and the check-in pack telling tenants to test monthly and report faults immediately protects both sides. It also gives you evidence of having set the expectation if an alarm is later found disabled.

Types of alarm

The regulations do not specify the type of alarm, only that alarms must be installed and working. However, the type you choose affects reliability, maintenance burden, and tenant satisfaction.

Battery-powered alarms

The cheapest option upfront, but batteries need replacing (typically annually for standard batteries). Sealed lithium battery alarms with a 10-year life are a better choice. They cost more initially (around £15 to £25 each) but require no battery changes for the life of the alarm.

Mains-wired alarms

Hardwired into the property's electrical system with a battery backup. These are more reliable and are required in new-build properties under Building Regulations. Retrofitting mains-wired alarms in an existing property requires an electrician. They can be interlinked so that when one alarm triggers, all alarms in the property sound.

Interlinked wireless alarms

A middle ground: battery or mains-powered alarms that communicate wirelessly. When one detects smoke or carbon monoxide, all linked alarms sound. This provides the safety benefit of interlinking without the cost of running new wiring. For properties with multiple storeys, interlinked alarms significantly improve the chances of occupants hearing an alarm triggered on a different floor.

For HMOs, interlinked fire detection systems are typically required under licensing conditions and may need to meet a higher standard (BS 5839-6 Grade D or above). Check your licence conditions carefully.

Testing requirements

You must ensure that all smoke and carbon monoxide alarms are in proper working order on the day a new tenancy begins. This means physically testing each alarm (pressing the test button and confirming it sounds) on the day the tenancy begins.

The regulations place the testing obligation on the landlord at the start of the tenancy. There is no ongoing legal obligation for the landlord to test alarms during the tenancy. Once the alarms are tested at the start, the tenant is expected to test alarms regularly and report any faults. However, best practice is to check alarms at every property inspection and replace batteries or faulty units promptly.

What to do at each tenancy start

• Test every smoke alarm by pressing the test button and confirming it sounds for at least three seconds.
• Test every carbon monoxide alarm in the same way.
• Replace any alarm that does not sound or sounds weakly.
• Check the manufacture or expiry date on each alarm. Smoke alarms should be replaced every 10 years; carbon monoxide alarms typically every 5 to 7 years (check the manufacturer's guidance).
• Record the test date, the result, and the location of each alarm.

Record keeping and documentation

The regulations do not explicitly require you to keep written records of alarm testing. However, not keeping records is a significant risk. If a tenant or local authority claims you did not test the alarms, you need evidence to prove you did.

What records to keep

For each tenancy, record the following:

• Date of alarm testing (should be the day the tenancy starts).
• Location of each alarm (e.g., "ground floor hallway", "first floor landing", "kitchen, CO alarm near boiler").
• Type and model of each alarm.
• Test result: passed or replaced.
• If replaced, the date and details of the new alarm installed.
• Confirmation that the tenant was present or that the test was conducted before handover.

Photographs of alarm locations with timestamps add another layer of evidence. Some landlords include alarm testing as part of their check-in inventory, which creates a single document covering the property's condition and safety compliance at the start of the tenancy.

HouseFile allows you to create a timestamped record of your compliance activities, including document delivery. When you combine alarm testing records with proof of delivering safety certificates like your gas safety certificate, you build a complete compliance trail for each property.

Penalties for non-compliance

If a local authority has reason to believe you have not complied with the alarm regulations, they will serve a remedial notice giving you 28 days to install the required alarms. If you fail to comply with the remedial notice within 28 days, the local authority can:

• Arrange for alarms to be installed in the property themselves (with the consent of the tenant).
• Impose a penalty charge of up to £5,000.

The penalty is per breach, so a property missing both smoke alarms and carbon monoxide alarms could attract more than one penalty. Local authorities set their own penalty amounts within the £5,000 maximum, and many publish their penalty policies online.

Missing alarms are not a legal bar to possession, and a tenant cannot use them to defeat a mandatory ground. On a discretionary ground, the court decides whether possession is reasonable, and a poor safety record will not help your case.

Can tenants claim compensation?

If a tenant suffers harm (carbon monoxide poisoning, fire injuries, or property damage) because alarms were missing or not working, you face potential civil liability. A personal injury claim arising from a failure to install working alarms could result in significant compensation. Your landlord insurance may not cover you if the loss resulted from a breach of your legal obligations.

Common mistakes landlords make

Based on local authority enforcement data and industry experience, the most common failures are:

1. Missing carbon monoxide alarms

Many landlords installed smoke alarms after the 2015 regulations but did not update their approach when the 2022 amendment expanded carbon monoxide alarm requirements to cover gas and oil appliances. If your property has a gas boiler, and most do, you need a carbon monoxide alarm in the room where it is located.

2. Not testing at tenancy start

Some landlords assume that because the alarms were working at the last inspection, they will still be working when a new tenant moves in. Batteries die, alarms expire, and tenants occasionally remove alarms during their tenancy. You must test on the day the new tenancy begins.

3. Using expired alarms

Alarms have a finite life. Smoke alarms should be replaced after 10 years; carbon monoxide alarms after 5 to 7 years. Check the date on every alarm. An alarm that is past its expiry date may not detect smoke or carbon monoxide reliably, even if it passes a button test.

4. Not covering every storey

A two-storey house needs at least two smoke alarms. A three-storey townhouse needs at least three. A property with a converted loft or basement used as living space needs alarms on those levels too. Landlords sometimes miss the top or bottom storey, particularly in HMOs where communal areas span multiple floors.

5. No records

The landlord tested the alarms but kept no record. Six months later, the tenant reports a faulty alarm and claims it was never working. Without records, you cannot prove otherwise. This is avoidable and unnecessary.

Alarms as part of your wider compliance

Alarm compliance is one part of a broader set of safety obligations that includes gas safety, electrical safety, fire safety, and property standards. Our landlord compliance checklist brings all these requirements together so you can track everything in one place.

For HMOs, fire safety requirements go well beyond basic alarms. You may need fire doors, emergency lighting, fire blankets, and fire extinguishers depending on the size and layout of the property and the conditions attached to your licence. Our HMO compliance checklist covers these additional requirements.

Practical tips

Here are steps you can take to stay on top of alarm compliance without it becoming a burden:

• Use sealed 10-year lithium battery alarms. They eliminate the need for annual battery changes and are cost-effective over their lifetime. Budget around £15 to £25 per alarm.
• Keep spare alarms. If a tenant reports a faulty alarm, you can replace it immediately rather than waiting for a delivery or an electrician.
• Add alarm testing to your check-in process. Make it a standard part of the inventory check so it never gets forgotten.
• Label each alarm with the installation date. A small sticker on the base with the month and year makes it easy to identify when replacements are due.
• Set calendar reminders for expiry dates. If you installed alarms across your portfolio at the same time, they will all need replacing at the same time. Plan ahead.
• Check alarms at every property inspection. While there is no legal obligation to test during the tenancy, checking at inspections catches problems early and demonstrates good practice.
• Include alarm information in the tenancy agreement. Tell tenants they should test alarms monthly, never remove or disable them, and report any faults to you immediately.

Alarm duties at a glance

The requirements are straightforward: a smoke alarm on every storey, a carbon monoxide alarm in every room with a fixed combustion appliance (except gas cookers), all tested and working at the start of each tenancy. Non-compliance can lead to penalties, and a missing or faulty alarm can have devastating consequences.

Keep records of every test, replace alarms before they expire, and make alarm checks a routine part of every tenancy. Together with your gas safety certificate, EICR, and EPC, working alarms are part of the basic safety standard every landlord has a duty to provide.

Alarms are one item on a longer list. The landlord document compliance guide goes through the documents and checks a let property needs, with the deadline for each.