Home › Guides › Smoke & carbon monoxide detector guide: placement, testing and replacement
GuideSmoke and carbon monoxide detectors are the cheapest life-saving devices in your home — but only if they're placed correctly, working, and not expired. Most people don't realize detectors have a lifespan and need replacing, not just new batteries. Here's how to make sure yours will actually protect your family.
Install smoke alarms on every level of the home, inside each bedroom, and outside each sleeping area. Mount them high (smoke rises) — on ceilings or high on walls — and keep them away from kitchens and bathrooms enough to avoid false alarms from cooking and steam, but close enough to detect real fires. Interconnected alarms (all sound together) give the earliest warning.
Carbon monoxide is odourless and deadly, produced by furnaces, gas appliances, fireplaces and attached garages. Place CO detectors on every level and near sleeping areas so an alarm wakes you. Follow the manufacturer's height guidance. If you have fuel-burning appliances or an attached garage, CO detection isn't optional.
Test every detector monthly with the test button — it takes seconds. Change batteries at least yearly (a common reminder is to do it at a clock change), or use long-life sealed battery units. A detector with a dead or missing battery is just a plastic disc on the ceiling — testing is what keeps them real.
This is the step most people miss: detectors don't last forever. Smoke alarms generally need replacing about every 10 years, and CO detectors roughly every 7–10 (check the date on the unit). The sensors degrade over time, so an old detector may not work even with a fresh battery. Check the manufacture date and replace on schedule.
Treat every alarm as real. For a smoke alarm, get everyone out and call for help — don't investigate. For a CO alarm, get everyone to fresh air immediately and then contact your gas utility or emergency services; CO poisoning symptoms (headache, dizziness, nausea) can be mistaken for the flu. Never ignore or disable an alarm that keeps sounding.
Pair detector checks with seasonal maintenance — testing at the clock change and replacing units on schedule. If you're installing or replacing hardwired or interconnected detectors, an electrician can handle it. On Genie you can book an electrician for detector installation, and it's a natural add-on to a furnace tune-up each fall.
Smoke alarms on every level, inside each bedroom and outside each sleeping area, mounted high. CO detectors on every level and near sleeping areas. Interconnected alarms that all sound together give the earliest warning.
Smoke alarms about every 10 years and CO detectors roughly every 7–10 — the sensors degrade, so an old unit may not work even with a fresh battery. Check the manufacture date on the unit.
Get everyone to fresh air immediately, then contact your gas utility or emergency services. CO is odourless and its symptoms resemble the flu — never ignore or disable the alarm.