Smoke and Carbon Monoxide Alarm Requirements for Landlords 2026

Smoke and carbon monoxide alarms save lives. For UK landlords, installing and maintaining them is not optional — it is a legal requirement with penalties of up to £5,000 for non-compliance. This guide covers exactly what you must do, where alarms need to go, how to test and document them, and what happens if you get it wrong.

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, not just solid fuel ones.

These regulations apply to all residential tenancies in England, including assured shorthold tenancies (now simply assured tenancies under the Renters' Rights Act 2025), licences to occupy, and tenancies of houses in multiple occupation (HMOs). 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.

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, mount the alarm between 600mm and 900mm below the apex, as dead air at the very top can delay detection.

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 — 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).

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 £15-25 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 tenant moves in, or as close to it as is reasonably practical.

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 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 5-7 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 tenancy start date or the day immediately before).
• 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 comprehensive 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 offence, so a property missing both smoke alarms and carbon monoxide alarms could attract multiple penalties. Local authorities set their own penalty amounts within the £5,000 maximum, and many publish their penalty policies online.

Beyond the direct penalty, non-compliance creates additional risks. Under the Renters' Rights Act 2025, demonstrable non-compliance with safety obligations weakens your position in any possession proceedings. A tenant can argue that a landlord who has not met basic safety requirements should not be granted a possession order, even on mandatory grounds.

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 5-7 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 does not exist in isolation. It 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 £15-25 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.

Summary

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. The penalties for non-compliance are real, and the safety consequences of getting it wrong can be devastating.

Keep records of every test, replace alarms before they expire, and treat alarm compliance as a core part of your lettings operation rather than an afterthought. Combined with your gas safety certificate, EICR, and EPC, working alarms form part of the safety baseline that every tenant has a right to expect and every landlord has a duty to provide.