What are the carbon monoxide alarm requirements for homes in Ontario?

Under the Ontario Fire Code, every home in Ontario must have working carbon monoxide alarms installed near all sleeping areas on every level of the home if the home has a fuel-burning appliance, an attached garage, or a fireplace. This includes furnaces, water heaters, gas stoves, gas fireplaces, wood stoves, and any other appliance that burns natural gas, propane, oil, or wood. Virtually every home in the GTA with a gas furnace — which is the vast majority — requires CO alarms.

Carbon monoxide is called the silent killer because it is completely odourless, colourless, and tasteless. You cannot detect it without an alarm. CO poisoning kills dozens of Canadians every year and sends thousands more to emergency rooms. In the GTA, the risk peaks during winter months when furnaces run continuously, homes are sealed tight against the cold, and ventilation is minimal. Toronto's bitter January and February temperatures — regularly dropping to minus 15 or minus 20 degrees Celsius — mean that furnaces cycle heavily, and any failure in the heat exchanger, flue pipe, or venting system can allow CO to enter your living space.

The Ontario Fire Code specifies that CO alarms must be installed adjacent to each sleeping area — meaning in the hallway outside bedrooms or within bedrooms themselves. If your home has multiple storeys, a CO alarm is required on every level that has a bedroom. A single CO alarm on the main floor does not satisfy the requirement if there are bedrooms on the second floor or in the basement. The alarms can be battery-operated, plug-in with battery backup, or hardwired with battery backup. However, for new construction and renovations in Ontario, the Ontario Electrical Safety Code requires hardwired, interconnected combination smoke and CO alarms — meaning when one alarm detects CO, all alarms in the house sound simultaneously.

Hardwired interconnected alarms require a licensed electrician to install because they involve running new dedicated circuits and connecting the alarms to your electrical system. This is particularly relevant in older GTA homes where the original construction predates CO alarm requirements entirely. Many homes in established Toronto neighbourhoods have battery-operated CO alarms that satisfy the minimum Fire Code requirement but lack the reliability and whole-home coverage of a hardwired interconnected system. The cost to install a hardwired interconnected smoke and CO alarm system in a typical GTA home ranges from $800 to $2,000 depending on the number of units needed and the difficulty of running wiring through finished walls and ceilings. An ESA permit is required for the new circuit.

CO alarms have a limited lifespan — typically 5 to 7 years — after which the sensor degrades and the alarm becomes unreliable. Check the manufacture date on the back of each alarm and replace any that have exceeded their rated life. Test all CO alarms monthly by pressing the test button. If you hear the CO alarm sound four quick beeps in a repeating pattern, evacuate everyone from the home immediately and call 911 from outside. Do not re-enter the home until emergency services have cleared it. If you need a licensed electrician to install hardwired CO alarms, Toronto Electrical Repair can help you find one through the Toronto Construction Network.