A new boiler, a wood burner, a gas hob: every one of them quietly burns fuel a few feet from where you sleep, cook and relax. Carbon monoxide has no smell, no colour and no taste, and a faulty appliance can produce it without a single warning sign you'd notice. So the question worth answering before you scroll any further is simple: what does carbon monoxide alarm law uk actually require of you in 2026, and where should the alarm go?
If you own and live in your home in England, there is no single law forcing you to fit a carbon monoxide alarm in every room — but there is one that reaches almost everyone, and most people don't realise it applies to them. Since 1 October 2010, the Building Regulations (Approved Document J) have required a CO alarm to be fitted whenever a new or replacement fixed combustion appliance is installed — a boiler, a wood burner, a gas fire [STAT: confirm AD J CO-alarm requirement and 2010 date]. So if you've had a new boiler put in this decade, the rule already reached you. The separate 2022 regulations everyone talks about apply to rented homes; if you let a property, the duty is stricter and explicit.
What the law actually says in 2026
For owner-occupiers in England, CO cover is triggered by work rather than blanket duty. When a registered installer fits a new boiler, stove or gas fire, Approved Document J expects a carbon monoxide alarm to go in alongside it. There is no separate requirement to retrofit alarms to appliances installed before that — which is exactly how older homes end up uncovered.
Rented homes are different. The Smoke and Carbon Monoxide Alarm (England) Regulations 2015, amended from 1 October 2022, require landlords to fit a CO alarm in any room used as living accommodation that contains a fixed combustion appliance — and to repair or replace alarms reported faulty [STAT: verify 2022 amendment scope and effective date]. Gas cookers are specifically excluded from that duty, a point we come back to below. You can read the regulations on gov.uk [LINK: gov.uk smoke and CO alarm regulations].
Scotland goes further than England. Since February 2022 every home — owner-occupied included — must have a CO alarm wherever there is a fixed combustion appliance or a flue [STAT: confirm Scottish CO alarm rule and date]. Wales tightened its rented-sector rules over the same period. If you're in England and own your home, you have the most discretion and, too often, the least protection.
Where the alarm has to go to actually work
A CO alarm only protects you if it's positioned to catch the gas before you breathe enough of it to matter. Fit one in the same room as each fuel-burning appliance. Ceiling-mounted alarms should sit at least 300mm from any wall and any light fitting; wall-mounted ones should be high up, above door and window height but at least 150mm below the ceiling [STAT: confirm placement distances per BS EN 50291 / manufacturer guidance].
Keep the alarm roughly one to three metres horizontally from the appliance — close enough to detect a problem, far enough that brief, normal fumes don't nuisance-trip it. Avoid mounting directly above a sink, a cooker, or next to an extractor or openable window, where draughts and steam skew the reading. Whatever you buy, check it carries the BS EN 50291 mark; a cheap unit without it is a false comfort. And if a flue or chimney runs up through a bedroom or landing, that room needs its own alarm too — the appliance may be downstairs, but the flue gases travel.
The one many homeowners miss: the gas cooker
Because gas cookers are written out of the rented-sector rules, a lot of homeowners assume they're a non-issue. They aren't. A gas hob or oven still burns gas, and a poorly maintained or badly ventilated one can produce carbon monoxide — yet the typical home has an alarm by the boiler and nothing within reach of the kitchen. If you cook on gas, fit an alarm in the kitchen, set a sensible distance back from the hob so everyday steam doesn't trigger it.
Here's the blunt version: treating carbon monoxide alarms as a landlord's problem is how owner-occupiers end up the least protected people on the street. You are not exempt from the gas just because you're exempt from the paperwork — and the gas cooker the regulations ignore is sitting in the room your family uses most.
Testing, lifespan and the replace-by date
Press the test button on every CO alarm once a month — it's the only way to know the sounder still works. Just as important, alarms expire: the sensor degrades whether or not it's ever detected anything. Sealed long-life units typically last around seven to ten years, replaceable-battery types often five to seven [STAT: confirm typical CO alarm lifespans]. Every alarm prints a 'replace by' date on the back; once it passes, the unit is decoration, not protection. And don't assume a smoke alarm has you covered — smoke and CO use entirely different sensors. If you ever suspect a leak, switch the appliance off, open windows, leave the property and call the Gas Emergency line, then have it checked by a Gas Safe registered engineer [LINK: Gas Safe Register find an engineer].
What to do in the next 30 minutes
• Walk your home and list every fuel-burning appliance: boiler, gas hob, wood burner, gas fire, gas water heater.
• Turn each existing CO alarm over and check the 'replace by' date — if it's passed, it isn't protecting anyone.
• Confirm you have an alarm in the same room as your boiler and any wood burner, plus one within reach of a gas hob.
• Check every unit carries the BS EN 50291 mark — it'll be printed on the casing. [LINK: related-guide]
• Press the test button on each alarm and note the date you did it, so you know when the next monthly check is due. [LINK: pillar-in-same-cluster]
Carbon monoxide alarms only protect you if they're in date and actually tested — and that's exactly the kind of small, forgettable job that slips for months. You can add CO-alarm checks to your Home+ reminders, and log each alarm's replace-by date alongside your boiler and appliance records, so the whole household's cover lives in one place and nothing quietly expires on the wall. [LINK: Home+ sign-up]
Frequently asked questions
Do I legally need a carbon monoxide alarm if I own my home?
In England there's no blanket duty to retrofit alarms to every appliance, but Building Regulations require one to be fitted whenever a new or replacement combustion appliance is installed. In Scotland, owner-occupiers must have CO alarms wherever there's a fixed combustion appliance or flue. Either way, fitting them is cheap and sensible regardless of what the law strictly compels.
Where exactly should a carbon monoxide alarm be placed?
In the same room as the appliance, roughly one to three metres away horizontally, high on a wall or on the ceiling away from walls and light fittings. Keep it clear of windows, extractors and the cooker itself so draughts and steam don't cause false alarms.
Do I need a CO alarm for a gas cooker?
It isn't legally required even in rented homes, because gas cookers are excluded from the regulations. But a gas hob or oven can still produce carbon monoxide, so fitting a kitchen alarm is a sensible precaution if you cook on gas — just position it a short distance from the hob to avoid nuisance trips.
How long do carbon monoxide alarms last?
Most last between five and ten years depending on the type, after which the sensor is no longer reliable. Check the 'replace by' date printed on the back of the unit and diarise it, because a working battery does not mean a working sensor.
Does a smoke alarm detect carbon monoxide?
No. Smoke alarms and CO alarms use different sensors and detect different things. You need both — a smoke alarm will not warn you about a carbon monoxide leak, and a CO alarm will not warn you about a fire.
