How do I look after smoke and carbon monoxide alarms?

Smoke alarms are the highest-value maintenance in any home and the most commonly neglected. The point people miss is that the unit itself has a lifespan: the sensor degrades over about ten years, so a decade-old alarm with a fresh battery may not work.

Safety

What you'll need

• Smoke alarms (one per floor minimum)
• Carbon monoxide alarm for any room with a fuel-burning appliance
• Batteries
• Step ladder (optional)

Step by step

1. Fit at least one smoke alarm on every floor, in hallways and landings.Ceiling-mounted, near the centre of the space, at least 30cm from walls and light fittings.
2. Fit a heat alarm rather than a smoke alarm in the kitchen.Smoke alarms in kitchens produce constant false alarms, which leads to them being disabled — which is the actual danger.
3. Fit a carbon monoxide alarm in any room with a fuel-burning appliance.Gas boiler, gas hob, wood burner, open fire. Follow the manufacturer's positioning guidance, which differs from smoke alarms.
4. Test every alarm monthly using the test button.It takes seconds. Attach it to something monthly you already do so it actually happens.
5. Change batteries annually, unless the unit has a sealed ten-year battery.A common prompt is when the clocks change. Sealed-battery units don't need this.
6. Vacuum the alarm casing every few months.Dust and insects inside the chamber cause both false alarms and reduced sensitivity.
7. Check the manufacture date on the back and replace the unit after ten years.This is the step almost everyone misses. The sensor degrades regardless of the battery.
8. Never remove the battery to stop a false alarm.It's how alarms end up permanently disabled. Fan the smoke away, or fit a heat alarm if it's a kitchen issue.
9. Make sure everyone in the house knows what each alarm sounds like and what to do.Smoke and CO alarms have different sound patterns and require different responses — CO means get outside, don't investigate.

Tips

• Interlinked alarms, where one sounding triggers all of them, are considerably safer in a multi-storey home. Radio-interlinked battery models avoid any wiring.
• In some parts of the UK, interlinked alarms are a legal requirement — check the current rules where you live, particularly if you let property.
• Ten-year sealed-battery alarms remove the annual battery job entirely and are worth the higher purchase price.
• Write the replacement date on the alarm in marker when you fit it. Nobody remembers otherwise.

Common mistakes

• Removing the battery to stop a false alarm — It's the most common reason alarms are found non-functional after a fire. Address the cause instead.
• Keeping alarms past ten years — The sensor degrades regardless of the battery. An old alarm may fail to detect a real fire.
• Putting a smoke alarm in the kitchen — Constant false alarms lead to it being disabled. A heat alarm is the correct choice there.
• No carbon monoxide alarm with a fuel-burning appliance — CO is odourless and colourless. There is no way to detect it without an alarm.

Questions people ask