Working smoke alarms on every storey and outside sleeping areas are required in Ontario homes, and carbon monoxide alarms are required near bedrooms in any home with a fuel-burning appliance, a fireplace, or an attached garage. As of January 1, 2026, Ontario's Fire Code expanded the CO requirement: alarms adjacent to each sleeping area and on every storey, including storeys without bedrooms. BC has parallel rules.
$30 to $100 per device DIY; ~$150 to $300 per hardwired device installedAddress immediatelyInterior
The ten second check
What else is typical in a house this age?
You are reading the smoke & carbon monoxide alarms page. Type the year the house was built and I will tell you what else tends to be true at that age, what it costs, and what to ask. One number, ten seconds.
Free. No account. Educational and impartial, not a home inspection.
Why it matters
This is the cheapest life-safety item in a house, and a surprisingly good tell. A home with missing, yellowed, or painted-over alarms is telling you something about how everything else was maintained. Alarms also expire: the replace-by date on the back is typically 10 years from manufacture.
How to spot it
Look at the hallway ceiling outside the bedrooms and on each floor, including the basement. Yellowed housings, paint on the unit, or a missing base plate all mean "replace." Check for a CO alarm near sleeping areas in any home with gas appliances, a fireplace, or an attached garage.
What it costs
$30 to $100 per device DIY; roughly $150 to $300 per device for hardwired replacements installed by an electrician.
What to do
Immediately on moving in, install fresh combination smoke/CO alarms wherever required, whatever the sellers had. It's the cheapest line item of the entire move.
Education and triage, not a home inspection. Placement requirements are fire-code specifics that vary by province and dwelling type, Casaroo notes what's visible; your local fire service confirms what is required.
Common questions
The house already has alarms. Do I still need to replace them?
Replace them on move-in regardless of what the sellers had. Alarms expire, typically ten years from manufacture, and at $30 to $100 per device, or $150 to $300 per hardwired device installed, they are the cheapest line item of your entire move.
What changed in Ontario in 2026?
As of January 1, 2026, Ontario's Fire Code expanded the carbon monoxide requirement to alarms adjacent to each sleeping area and on every storey, including storeys without bedrooms. Your local fire service confirms exactly what your dwelling type requires.
Why do missing alarms matter beyond the alarms themselves?
Because they are a tell. A house with painted-over, yellowed, or missing alarms is telling you something about how everything else in it was maintained. Treat it as a prompt to look harder, not just as a hundred-dollar fix.
Do I need a CO alarm if I have no gas appliances?
Ontario requires them near sleeping areas in any home with a fuel-burning appliance, a fireplace, or an attached garage, so an attached garage alone puts you in scope. Confirm your specific situation with your local fire service.
Last reviewed 2026-07-10.
This guide is general education, not a home inspection and not advice for your specific property. Always
consult the appropriate licensed professional, and get a licensed home inspection before you remove conditions
or buy. Cost ranges are 2026 estimates that vary by region, size, and access; confirm specifics with a
qualified professional.