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OBC DIVISION B · PART 9 · SECTION 9.10 — FIRE PROTECTION

When are carbon monoxide alarms required in Ontario homes?

CO alarms are required in every dwelling that contains a fuel-burning appliance (gas furnace, fireplace, water heater) or has an attached garage. They must be installed adjacent to each sleeping area, hardwired or plugged in per the standard.

Code reference
Where a fuel-burning appliance is installed in a dwelling unit, or where a dwelling shares a wall, floor or ceiling with a garage or a service room containing fuel-burning equipment, carbon monoxide alarms conforming to CSA 6.19 must be installed adjacent to each sleeping area, permanently connected or otherwise powered as the provisions permit.
OBC Division B, Subsection 9.33.4.

Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.

What this means in practice

Almost every Ontario house with gas heat or an attached garage needs CO alarms beside the bedrooms; 'adjacent to each sleeping area' typically means the hallway serving the bedrooms, within audible range through closed doors. In buildings, suites above or beside garages and service rooms are also captured. The Ontario Fire Code retroactively requires CO alarms in existing homes with fuel appliances or attached garages, so this is not just a new-construction rule. Combination smoke/CO units simplify compliance; check replacement dates, as CO sensors expire in roughly 7-10 years.

Plain language

If your home burns any fuel, gas furnace, fireplace, gas water heater, or has an attached garage, you must have carbon monoxide alarms near the bedrooms. CO is invisible and odourless, so the alarm is your only warning.

Related questions

What fire separation does a basement apartment need in Ontario?Where are smoke alarms required in a house in Ontario?What separation is required between an attached garage and the house in Ontario?

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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.