Smoke alarms and carbon monoxide detectors save lives — but only when they are correctly positioned, interconnected, and maintained. UK regulations on domestic detection have strengthened significantly since 2022, and many owner-occupiers are unaware that changes to their heating system or an extension to their home may now require them to upgrade to a higher standard of protection.
The 2022 Changes to Building Regulations
From 1 October 2022, Approved Document J (Combustion Appliances) was updated to require a carbon monoxide alarm in any room where a fixed combustion appliance is installed — not just new installations, but any room where a new appliance is fitted or an existing one is replaced. This brought owner-occupied homes into scope alongside rental properties for the first time.
"From 1 October 2022, landlords are required to install a carbon monoxide alarm in any room used as living accommodation that contains a fixed combustion appliance (excluding gas cookers). Owner-occupiers are subject to the same requirement when having a new or replacement appliance installed."— GOV.UK — Smoke and Carbon Monoxide Alarms: Guidance for Landlords
Grades of Alarm — What Grade D Means
The British Standard for domestic fire detection is BS 5839-6. It defines alarm grades from A (full commercial-grade system) to F (battery-only alarm). For most existing homes, Grade D (mains-powered, battery backup, interlinked) is the recommended standard. New-build homes require at least Grade D; some higher-risk situations require Grade C (with a control panel) or above.
Where Alarms Must Be Located
BS 5839-6 Category LD2 (the minimum recommended for most dwellings) requires smoke alarms in all circulation areas (hallways and landings) and in the principal habitable room (usually the main living room). Category LD1 extends this to all rooms where a fire is likely to start — which in practice means kitchen and bedrooms too. CO alarms must be positioned at breathing height (not ceiling height — CO disperses differently from smoke), within 1–3 metres of a combustion appliance, and away from doors or windows that might dilute the gas.
"Carbon monoxide alarms should be sited between one and three metres from the combustion appliance, at the height at which an occupant would be breathing. Ceiling-mounting is appropriate for alarms in open-plan spaces; wall-mounting at head height is acceptable in other rooms."— HSE — Carbon Monoxide Alarms in the Home
When an Electrician Is Needed
A battery-only alarm can be fitted by any competent person. A mains-powered, interlinked alarm system requires a connection to the mains supply — this is notifiable electrical work if it involves a new circuit or connection to a fused connection unit. In practice, most mains alarm installations connect to a spur from the lighting circuit; the work is straightforward but must be carried out (or inspected and certified) by a registered electrician if it involves any new wiring.
Where alarms are being upgraded as part of a broader rewire or renovation, coordinate the alarm positions with the electrical first fix — this avoids the alternative of drilling finished ceilings after plastering. An interlinked system means that if one alarm activates, all alarms in the property sound simultaneously — this is a requirement for new-build under Building Regulations Approved Document B and is strongly recommended for all existing homes.
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