Fire and smoke alarm costs depend on what you need — from upgrading a home to interlinked alarms, through HMO detection, to a full commercial fire-alarm system. Here’s a realistic 2026 breakdown.

Domestic interlinked alarms

For a typical home upgrading from standalone battery alarms to interlinked, mains-powered detection (the modern standard):

• Per interlinked mains alarm, supplied and fitted: ~£80–£150
• A typical house (smoke alarms per storey + a heat alarm in the kitchen + CO where needed): ~£300–£600
• Radio-interlinked alarms (wireless link, ideal for period homes to avoid chasing cables) can cost a little more per unit but save on labour and disruption

The big variables are how many alarms, whether it’s hard-wired or radio-interlinked, and access.

CO alarms

A carbon monoxide alarm (required in any room with a fixed combustion appliance) is relatively inexpensive — typically £40–£80 supplied and fitted, depending on type.

HMO detection

HMOs need a higher standard of graded, interlinked detection, so they cost more than a standard home — the exact figure depends on the size of the property and the grade of system required. An assessment is the only way to price it accurately. See our HMO EICR and AFDD guidance.

Commercial fire-alarm systems

Commercial premises fall under BS 5839-1 and are priced per system, driven by the size of the building, the category of system required, and the number of detectors and call points. These are quoted individually after a survey rather than off a price list.

What affects domestic cost

• Number of alarms (one per storey minimum, plus heat alarm and CO where needed)
• Hard-wired vs radio-interlink — radio saves labour in period homes
• Property type and access — chasing cables in solid walls costs more
• Mains vs battery — mains interlinked is the standard for upgrades and worth it

Why interlinked is worth the cost

Standalone battery alarms are cheap but far less safe — a fire downstairs may not wake people upstairs. Interlinked alarms all sound together, wherever the fire starts. For a modest extra cost over standalone units, it’s one of the best safety upgrades you can make. See our smoke alarm regulations guide for what’s required.

Keeping costs sensible

• Do the whole home in one visit — cheaper than piecemeal
• Choose radio-interlink for period homes to avoid plaster damage and decoration costs
• Combine with other work (a rewire or board upgrade) if you’re having it done anyway

Get a fire alarm quote

For interlinked, compliant fire and smoke alarms — domestic, HMO, or commercial — at a fair, clearly-quoted price across East London, GFL Electrical are your local NICEIC electricians. See our fire & smoke alarm service or call 020 3774 5604.