Smoke and CO alarm rules in Ontario

This guide summarises what the Ontario rules require for smoke and carbon monoxide (CO) alarms in homes, using the Ontario government's own published guidance. It is a plain-language summary, not legal advice. The legal text is the Ontario Fire Code (O. Reg. 213/07), made under the Fire Protection and Prevention Act, 1997. If your situation is unusual, your local fire department's fire prevention office is the authority to ask.

Smoke alarms: what the law requires

According to the Office of the Fire Marshal's home fire safety page, every home in Ontario must have a working smoke alarm on every storey and outside all sleeping areas.

• Homeowners must install and maintain the smoke alarms in their home.
• Landlords must make sure their rental properties comply.
• Tenants who do not have the required alarms should contact their landlord immediately. It is against the law for tenants to remove batteries or tamper with an alarm.

The same page states that failing to comply with the Fire Code smoke alarm requirements can result in a $360 ticket or a fine of up to $50,000 for individuals or $100,000 for corporations.

Smoke alarms: what the Fire Marshal recommends

• Test monthly using the test button.
• Replace batteries at least once a year, or as the manufacturer recommends, and whenever the low-battery chirp sounds.
• Replace alarms every 10 years, following the manufacturer's instructions. The date is printed on the alarm.
• Mount on the ceiling where possible, or high on a wall, away from bathrooms, windows, ceiling fans and cooking appliances.
• Look for a CSA or ULC mark to make sure the alarm meets Canadian standards.
• Consider both types. Ionization alarms may respond slightly faster to flaming fires; photoelectric alarms may be quicker for slow, smouldering fires. Photoelectric alarms near kitchens can reduce nuisance alarms.
• Hardwired alarms should have battery backup in case of power failure.

Carbon monoxide alarms: when they are required

The Ontario government's carbon monoxide safety page says a house must have CO alarms if it:

• has a fuel-burning appliance (for example a gas furnace, gas water heater or gas stove),
• has a fireplace,
• has an attached garage, or
• is heated by air from a fuel-burning appliance that is not inside the home (new, in effect January 1, 2026).

Carbon monoxide alarms: where they go

• Adjacent to each sleeping area, meaning in the hallway or area outside the bedrooms.
• On every storey of the home, including storeys with no bedrooms. This requirement took effect on January 1, 2026. If your basement has a furnace but nobody sleeps there, it now needs a CO alarm too.

Apartments and condo units have additional triggers, such as being directly above, below or beside a building service room or garage. The province has published one-page information sheets, including CO alarm rules for existing homes (PDF).

Carbon monoxide: who is responsible

Building owners are responsible for compliance. In rental units, landlords must install and maintain CO alarms, test them annually and at certain other times (including a change of tenancy), and give tenants the maintenance instructions. Tenants must tell the landlord about any problem with a CO alarm, and nobody may remove batteries or tamper with one.

Types of CO alarms allowed

Under the Fire Code, CO alarms may be hardwired, battery-operated or plug-in. Combination smoke and CO units are common; make sure everyone at home knows the difference between the two alarm sounds.

If a CO alarm goes off

The province's guidance is direct: get everyone out of the home immediately and call 911 from outside. Do not go back in to find the source.

A quick self-check

1. Walk every storey, including the basement. Is there a smoke alarm on each one?
2. Stand in the hallway outside the bedrooms. Is there a smoke alarm and, if you have any fuel-burning appliance, fireplace or attached garage, a CO alarm?
3. Since January 1, 2026: is there a CO alarm on every storey?
4. Check the manufacture date on each alarm. Anything over 10 years old should be replaced.
5. Press the test button on each one.

Our Home Safety Score includes these questions and flags anything that looks out of line with the rules. For the full official picture, start with the Ontario government's fire safety legislation page.

More guides

• What to do after a break-in in Ontario
• Home safety checklist for aging parents
• Security tips for new homeowners

This guide is general information, not legal or professional advice. In an emergency, call 911.