Ontario Carbon Monoxide Alarms: What Landlords Must Do Before Winter

TORONTO, October 22, 2026 — The Technical Standards and Safety Authority (TSSA) today published a Carbon Monoxide Backgrounder ahead of Carbon Monoxide Awareness Week, November 1 to 7, set by the Hawkins Gignac Act. It names poor maintenance of fuel-burning appliances as the main cause of home CO incidents and notes that the Fire Code's CO alarm rules widened on January 1, 2026. This is the first heating season under those rules, and in rental units the duty to install, test and maintain Ontario carbon monoxide alarms sits with landlords.

What changed on January 1, 2026

The province's CO safety page and rule sheets describe two additions. First, a CO alarm is now needed on every storey of a unit, including storeys with no bedroom, as well as next to each sleeping area. Second, a unit heated by air from a fuel-burning appliance outside it, such as a furnace in a shared service room or a utility shed, now triggers the rules even if the unit has no appliance of its own.

In multi-unit buildings, alarms are also required in each service room with a fuel-burning appliance, in units sharing a wall or floor/ceiling with that room or a garage, and in public corridors heated by a fuel-burning forced-air system. Buildings whose alarms were installed under the Building Code as it read on or after January 1, 2025 follow that code instead.

What it means for landlords

For a rental unit, the Fire Code makes the landlord (including an agent such as a property manager) responsible. You must:

• Install alarms where Section 2.16 requires them. Hardwired, battery or plug-in units are all allowed if they meet CSA 6.19 or UL 2034 and sit at the manufacturer's recommended height. An alarm by a sleeping area must be audible throughout it with doors closed.
• Keep them working, including their primary and backup power supplies.
• Give each tenant a copy of the manufacturer's maintenance instructions.
• Test every alarm using its test feature at least once a year, after every change of tenancy, after replacing a battery and after any change to the circuit a hardwired alarm is on.
• Replace alarms within the time frame the manufacturer sets, with a replacement that still meets Section 2.16.

The Fire Code (Article 2.6.1.4) also requires every chimney, flue and flue pipe to be inspected for dangerous conditions at least every 12 months. For the appliances themselves, the TSSA advises a yearly inspection by a TSSA-registered contractor, and the province advises the same before cold weather. With your repair duty under s. 20 of the Residential Tenancies Act, 2006, treat an annual service as part of the job. Our guide to maintenance standards and the landlord's duty to repair in Ontario covers that wider duty.

A Fire Code breach is an offence under the Fire Protection and Prevention Act, 1997, with fines of up to $50,000 for an individual's first offence and up to $500,000 for a corporation's.

What it means for tenants

Tenants have two duties. You must tell your landlord as soon as you know that an alarm in your unit is disconnected, not working or impaired, and no one, tenant or landlord, may disable a CO alarm. If an alarm sounds, get everyone out and call 911 from outside the building.

What to do now

1. Walk each unit: list every storey and sleeping area, and note any fireplace, gas appliance, attached garage or shared furnace.
2. Add alarms where Section 2.16 now requires them, starting with storeys that have no bedroom.
3. Test every alarm, check the expiry date printed on it, and write down the date and result.
4. Book the furnace, water heater, fireplace and venting for service with a TSSA-registered contractor before the heating season.
5. Send tenants the maintenance instructions, and ask your local fire department if unsure what your building needs.

See also multi-unit vs single-unit compliance, the tenant turnover guide and minimum heat bylaws by city.