When does my Toronto basement bedroom need a carbon monoxide alarm?

Not every basement bedroom needs one: the Ontario Fire Code requirement depends on what is in the home. A carbon monoxide (CO) alarm is required in a home that has a fuel-burning appliance, a fireplace or an attached garage, and since January 1, 2026 also in a home that "is heated by air from a fuel-burning appliance that is not contained within your home," according to the Ontario Fire Marshal.

Where the alarm goes

In a home that needs CO alarms, the Fire Code requires one "adjacent to each sleeping area" and, since January 1, 2026, on each storey without a sleeping area as well. The Fire Marshal explains "adjacent" as "the hallway or area outside the sleeping area." So a basement bedroom in a home with a gas furnace needs an alarm in the hallway or area outside that bedroom.

On height, the Fire Code says to install the alarm "at the manufacturer's recommended height or, if the manufacturer has not recommended a height, on or near the ceiling."

A separate basement unit. Where a house has two units, the Fire Code also requires an alarm adjacent to each sleeping area within a suite that shares a wall or a floor/ceiling with the service room where the fuel-burning appliance is. The Fire Marshal publishes a separate sheet for houses with two or more units, which is worth reading before a suite is rented.

Which type of alarm. In an existing home, hardwired, battery-operated and plug-in alarms are all allowed under the Fire Code. In new construction, the Building Code requires alarms permanently connected to an electrical circuit with a backup battery, interconnected in a house with a secondary suite.

Rental units. For a rented suite, the Fire Code treats the landlord as the owner for these rules. The landlord must test the CO alarms annually and after every change in tenancy, and give the tenant the maintenance instructions.

Upkeep. The Fire Marshal advises testing CO alarms every month and replacing the batteries every year. Replace the alarm itself within the time frame in the manufacturer's instructions.

If you are finishing a basement bedroom or adding a suite, ask the contractor which alarms the plans call for, where each one goes, and who installs any hardwired units. You can describe your project through the Toronto Construction Network to be matched with local contractors.