Smoke and Carbon Monoxide Alarm Rules in Rented Homes

Every rented home in the UK is legally required to have smoke alarms, and most also need carbon monoxide alarms, but the exact rules depend on which nation you live in and what kind of heating and cooking appliances the property has. In England, the law changed on 1 October 2022: all relevant landlords must provide a carbon monoxide alarm in any room used as living accommodation that contains a fixed combustion appliance, with gas cookers excluded¹. In Scotland the rules go further than anywhere else in the UK, applying to every home regardless of whether it is rented, owner-occupied or otherwise, from 1 February 2022².

The duties sit with the landlord, not the tenant. A landlord in England must repair or replace an alarm once told it is faulty, in both the private and social sectors². Government advice for tenants is to test smoke alarms and carbon monoxide detectors regularly, at least once a month³. The alarms themselves are cheap: official guidance puts carbon monoxide alarms at from £15, sold in most hardware shops¹, and the rules on which alarms count are specific, resting on the European standard EN 50291 and a Kitemark or equivalent approval mark.

This page sets out the requirements nation by nation, the standards an alarm must meet, where it should be fitted, who tests it, and what it costs. It sits alongside our wider coverage of landlord duties on energy, heating and home safety and what tenants can and cannot change in a rented home.

What landlords in England must provide

The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 require landlords to ensure that any room used as living accommodation which contains a fuel-burning appliance is equipped with a carbon monoxide alarm, with gas cookers excluded from the requirement⁵. The Health and Safety Executive states the change plainly: "From 1st October 2022 the law changed in England and all relevant landlords must provide a carbon monoxide alarm in any room used as living accommodation which contains a fixed combustion appliance (excluding gas cookers)"¹.

Two features of the English rules matter in practice. First, the duty is triggered by the appliance, not by the type of heating system: a fixed gas boiler, a wood-burning stove or an oil-fired range each counts as a fixed combustion appliance, so the room containing it needs an alarm. Second, the duty to provide is matched by a duty to maintain. Both private and social sector landlords must repair or replace alarms once they have been informed that the alarms are faulty². A tenant who reports a beeping or dead alarm is therefore triggering a legal obligation, not making a polite request.

The rules may yet widen. A consultation published in September 2026 by the Chartered Institution of Building Services Engineers records proposals to extend the Smoke and Carbon Monoxide Alarm Regulations (England) 2015 and the provisions in Building Regulations Approved Document J, including making carbon monoxide alarms mandatory in rental properties with heating of any fuel type, and extending the regulations to require smoke and carbon monoxide alarms in social housing⁶. If adopted, that would close the gap for homes heated electrically, which currently fall outside the combustion-appliance trigger. Tenants in England can read more about the wider framework in our page on the Renters' Rights Act and home energy.

A smoke alarm for each floor of your home

Alongside the carbon monoxide rules sits a simpler and older requirement on smoke alarms: one on every floor. Government advice to landlords and letting agents is to fit smoke alarms on every floor of the property³. In Wales, the Fitness for Human Habitation Regulations require a smoke alarm, in proper working order, to be present on every storey of a dwelling⁴.

The "every storey" rule is about coverage, not headcount. A three-storey terraced house needs three smoke alarms, one per level, so that a fire on any floor is detected close to where it starts and the warning carries through the circulation space. A bungalow needs one. The rule says nothing about rooms within a storey, which is why the placement of the alarm on each floor matters as much as the count.

In Northern Ireland, the Private Tenancies Act (Northern Ireland) 2024 adds a timing rule: each smoke, heat or carbon monoxide alarm must be in proper working order at the beginning of every new tenancy⁷. That means a landlord cannot let a property with a dead battery in the hall alarm and leave the tenant to discover it. The same legislation requires a carbon monoxide alarm in any room or circulation space containing a fixed combustion appliance or a flue, and it requires carbon monoxide alarms to be installed and maintained in accordance with British Standard BS EN 50292⁷.

Scottish rules apply to all households, not only rentals

Scotland stands apart, because its alarm rules apply to all homes, not only rented ones. The Housing (Scotland) Act 1987 (Tolerable Standard) (Extension of Criteria) Order 2019 introduced new requirements for fire and carbon monoxide detection and warning equipment into the tolerable standard, the legal minimum below which a house must be brought up to standard⁸. The Order requires that a house has "satisfactory equipment installed for detecting, and for giving warning of, carbon monoxide present in a concentration that is hazardous to health"⁹.

The change took effect on 1 February 2022, when the detection requirements that had applied to private rented housing under the Repairing Standard were incorporated into the tolerable standard and extended to all tenures¹⁰. The Scottish Government's summary of the regulations is direct: the standards for provision of fire and smoke alarms, and for carbon monoxide alarms, in private rented housing "will be extended to all tenures"¹¹. A house now meets the tolerable standard only if it complies with the relevant requirements for satisfactory carbon monoxide alarms¹².

What that means in practice is a carbon monoxide alarm in all rooms where there is a fixed combustion appliance, excluding an appliance used solely for cooking, or a flue². Private landlords in Scotland must ensure a detection system is installed in all dwellings they rent where there is a fixed combustion appliance, or where one sits in an inter-connected space such as an integral garage¹⁰. Scottish carbon monoxide alarms must meet the relevant British Standards, EN 50291-1².

The Scottish standard has real teeth in the rented sector because it interacts with the Repairing Standard, the set of duties a landlord must meet. It also reaches owner-occupiers, which no other UK nation's alarm rules do. Even government-funded improvement schemes reflect the priority: under Warmer Homes Scotland, smoke alarms and carbon monoxide detectors were the two most frequently installed measures, both of them mandatory under the scheme¹³.

How Wales and Northern Ireland phrase the requirement

Wales frames its rules through fitness for human habitation rather than through a dedicated alarm regulation. The Renting Homes (Wales) Act 2016, under the Fitness for Human Habitation regulations, mandates landlords to ensure working carbon monoxide alarms are fitted in properties with gas, oil-fired or solid fuel-burning appliances¹⁴. The Welsh Government's guidance to landlords spells out the requirement: a landlord must ensure a carbon monoxide alarm is present in any room which has a gas, oil or solid fuel burning appliance installed⁴. The same guidance requires the smoke alarm on every storey described above.

The Welsh requirement does not exist in isolation. The guidance is clear that it does not replace duties under existing legislation, including the Management of Houses in Multiple Occupation (Wales) Regulations 2006 and the Gas Safety (Installation and Use) Regulations 1998⁴. Tenants in Wales can read more in our page on fitness for human habitation in Welsh rented homes.

Northern Ireland combines a rented-sector duty with a building regulations duty. The Private Tenancies Act requires carbon monoxide alarms to be installed in privately rented homes and places a duty on landlords to repair them¹⁵. Separately, the Building Regulations (Northern Ireland) 2012 require that where a combustion appliance is installed in a dwelling, "reasonable provision shall be made to detect and give warning of the presence of carbon monoxide gas at levels harmful to people"¹⁶. The technical guidance behind that requirement, Technical Booklet L, states that carbon monoxide alarms should comply with BS EN 50291 and be powered by a battery designed to operate for the working life of the alarm¹⁷. Fitting CO alarms in a dwelling does not require notices or the deposit of plans under the 2012 regulations¹⁸.

Meeting the standards: EN 50291 and the Kitemark

Not every alarm on a shelf meets the law. The Health and Safety Executive's advice is to check before purchasing: "always ensure it complies with British Standard EN 50291 and carries a British or European approval mark, such as a Kitemark"¹. nidirect, the Northern Ireland government service, says the same: an alarm should meet British or European standards, the BS Kitemark or EN 50291¹⁹. The Heating and Hotwater Industry Council puts it as a two-part test: choose alarms compliant with EN 50291 and displaying a Kitemark²⁰.

The standard has evolved, and the version cited depends on the document doing the citing. Energy UK advises looking for alarms marked with the EN50291 standard, which may be written as BSEN 50291 or EN50291, together with the CE mark, and a Kitemark or Loss Prevention Certification Board (LPCB) logo²¹. The HSE's leaflet on carbon monoxide tells householders to ensure an alarm meets current safety standards, BS EN 50291, and carries the Kitemark²². Older guidance cites BS 50291:2001²³, while the current Welsh approved document cites BS EN 50291-1:2018²⁴. In practice, an alarm marked to EN 50291 with a Kitemark or equivalent approval mark satisfies the requirements across the UK nations.

A compliant alarm has two further features worth checking on the box. It should include an integral sounder, so the warning is audible without any separate device²⁴. And it should be powered by a battery designed to operate for the working life of the alarm, which is the pattern the building regulations guidance for combustion appliances expects¹⁷. Mains-powered BS EN 50291 Type A alarms with fixed wiring, not plug-in types, may also be used, provided they are fitted with a sensor failure warning device²⁵.

Choosing the right position and height for your alarm

The placement rules are more precise than most people expect. The starting point is the room containing the appliance. Met Office seasonal advice states that a carbon monoxide alarm should be fitted in any room that contains a gas fuel burning appliance, like a boiler and gas fire, and a solid fuel burning appliance²⁶. Where a new or replacement fixed solid fuel appliance is installed in a dwelling, a carbon monoxide alarm should be provided in the room where the appliance is located²³.

The current Welsh approved document extends the requirement to every space containing a fixed combustion appliance, including connected spaces such as attached garages and loft spaces, and, in high-risk accommodation such as a bedroom or principal habitable room, where a flue serving a combustion appliance passes through those rooms²⁴. The detailed siting rule from the building regulations guidance is as follows: on the ceiling at least 300mm from any wall or, if on a wall, as high up as possible, above any doors and windows, but not within 150mm of the ceiling, and between 1m and 3m horizontally from the appliance²⁵.

• Same room as the appliance, between 1m and 3m horizontally from it²⁵
• Ceiling fitting: at least 300mm from any wall²⁵
• Wall fitting: as high as possible, above doors and windows, but not within 150mm of the ceiling²⁵
• Keep it at least 1 metre away from fires, boilers, cookers or heaters²¹
• Boiler rooms and cupboards: if the appliance is in a space not normally used, the alarm should be located just outside that room or space¹⁷

On height, Energy UK's guidance is that if the alarm is fixed to a wall it should be positioned at head height, at breathing level, and it should not be placed on a ceiling²¹. The Welsh Government's landlord guidance offers a general rule that carbon monoxide alarms are usually installed lower than smoke alarms⁴. The apparent tension between "as high up as possible" and "head height" resolves in practice: the wall-mounted alarm goes at breathing level, high on the wall but clear of the ceiling's dead air zone. In Northern Ireland, the siting and maintenance benchmark is British Standard BS EN 50292⁷.

Keeping alarms working: checks, power and renewal

Provision is the landlord's job; routine testing falls to whoever lives with the alarm. Government advice to tenants is to test smoke alarms and carbon monoxide detectors regularly, at least once a month³. The Heating and Hotwater Industry Council's advice is to test alarms regularly as per the instructions²⁰, which matters because the test routine differs between models and the manufacturer's wording governs.

Carbon monoxide alarms do not last forever, and they age faster than smoke alarms. The Welsh Government's guidance notes that carbon monoxide sensors are usually more fragile than those within smoke alarms and usually need to be replaced more regularly⁴. The guidance accompanying carbon monoxide alarms should always be followed carefully, including noting the expiry date⁴. A compliant alarm should incorporate a warning device to alert users when the working life of the alarm is due to pass²⁴, so an intermittent chirp years into service is often the alarm announcing its own retirement rather than a fault.

The battery design matters here. Because the expected pattern is a sealed battery designed to last the working life of the alarm¹⁷, there is normally no battery to swap: when the unit reaches end of life, the whole alarm is replaced. That makes the end-of-life warning the single most important feature to check when an alarm is fitted, and the reason the expiry date should be noted when the alarm goes up.

What to do when your alarm goes off

The response to a sounding carbon monoxide alarm is the same across the UK, and it is not to investigate. nidirect's advice is to turn appliances off, open windows and get out of the house to breathe in fresh air¹⁹. UK Health Security Agency guidance is blunter still: stop using all appliances and evacuate the property immediately²⁶.

One limitation deserves to be stated firmly. The alarm will not go off if you are being exposed to lower levels of carbon monoxide²⁶. An alarm is calibrated to warn at concentrations hazardous to people, which means low-level exposure, the kind that causes chronic symptoms, can pass unannounced. That is why the alarm is a backstop and not a substitute for annual servicing of gas appliances and for knowing the signs of carbon monoxide poisoning in the home. Households that may qualify should also check whether they can get a free annual gas safety check.

Prices and responsibility for payment

Carbon monoxide alarms are among the cheapest pieces of safety equipment a home needs. HSE guidance states that CO alarms cost from £15 and can be purchased in most hardware shops¹. Energy UK gives the same starting point, around £15, and notes that portable carbon monoxide alarms are available from DIY shops, supermarkets, or directly from energy suppliers²¹. nidirect quotes from as little as £20¹⁹. The small differences between those figures reflect the date and the range of models each body looked at, not a disagreement about the order of magnitude.

Who pays depends on tenure and nation. In England the landlord must provide the alarm in every room that requires one¹, and must repair or replace it once told it is faulty². In Northern Ireland the Private Tenancies Act places the same duty to repair on landlords¹⁵. In Wales the Fitness for Human Habitation regulations put the duty on the landlord⁴. In Scotland the duty sits with the owner of the home under the tolerable standard, whatever the tenure¹². A tenant may also be able to get an alarm from the landlord or the local council²¹. For the wider picture of what landlords must fund, see our page on landlord duties on energy, heating and home safety.

The protection alarms offer and their limits

An alarm is a warning device, and its value to a household's safety is exactly that and nothing more. It detects carbon monoxide at levels harmful to people and gives an audible warning¹⁶. It does not prevent carbon monoxide being produced, it does not confirm an appliance is safe, and it stays silent at lower levels of exposure²⁶. It does not detect the fuel itself, so it offers nothing against a raw gas leak, and it does not replace the annual gas safety check that the Gas Safety (Installation and Use) Regulations 1998 continue to require⁴.

For a household thinking about energy independence, the honest reading is this. A carbon monoxide alarm reduces dependence on nothing: it adds a layer of warning around the combustion appliances a home already has, whether the fuel is gas, oil, coal or wood. Homes that move away from combustion altogether, to electric heating, remove the hazard the alarm guards against, which is one reason the 2026 consultation proposals to require alarms in rental properties with heating of any fuel type are notable⁶. Until then, the alarm remains the last line of defence for any home that burns fuel, and the law across all four nations treats it as a minimum standard rather than an optional extra.