Carbon Monoxide Alarm Rules by Province: Which Canadian Homes Must Have One, and Where It Must Go

Ontario: the strictest existing-home rule in Canada

Ontario's duty applies to every existing home with a fuel-burning appliance, a fireplace, an attached garage, or heating air supplied by a fuel-burning appliance outside the home, such as a furnace in a utility shed. That last trigger is new as of January 1, 2026.

The placement rule now has two parts. An alarm adjacent to each sleeping area, which has been the law since the regulation came into force on October 15, 2014. And since January 1, 2026, an alarm on every storey, including storeys with no bedrooms.

The province's own fact sheet for existing homes confirms that retrofit alarms may be hardwired, battery-operated or plug-in, and must carry a recognized certification mark such as CSA, ULC or Intertek/ETL. In rental homes, the landlord carries the duty.

The practical effect: a two-storey house with a finished basement and bedrooms upstairs now needs at least three alarms, one near the bedrooms, one on the main floor, and one in the basement. Homes that complied in 2025 may not comply today.

The full breakdown of the 2026 change, including what counts as a storey, is covered in our guide to Ontario's new CO alarm requirements for 2026.

Saskatchewan: retrofit since 2022, and Henry's Law on November 1

Saskatchewan moved from new-construction-only to a full retrofit duty in one step. Since July 1, 2022, CO alarms have been required in all residential buildings with a fuel-burning appliance or attached garage, "regardless of the date the building was constructed," according to the Government of Saskatchewan. Before that, the requirement covered only homes built after 2009.

The province is specific about hardware. Acceptable units are hardwired alarms, plug-in alarms, or alarms with a 10-year tamper-resistant battery. Placement follows the model code: within 5 m of each bedroom, measured along the hallway, on each level with a hazard.

The next change lands on the first day of CO Awareness Week. Under what the government calls Henry's Law, named for 11-year-old Henry Losco, who died of carbon monoxide poisoning, every residential suite in a multi-unit building must have a CO alarm "regardless of location in the building," effective November 1, 2026, as CBC News reported in May. It applies to new and existing buildings alike.

This is the most important structural shift in the table. Every other rule in Canada asks whether a suite has a trigger. Henry's Law stops asking. An all-electric apartment three floors above a gas boiler room is covered, because CO does not respect the trigger map.

Yukon: the first jurisdiction to require it

Yukon was first. On May 2, 2013, it became the first Canadian jurisdiction to make CO alarms mandatory in residences with fuel-burning appliances or attached garages, 17 months before Ontario.

The rule is still in force. "Yukon homes with an attached garage or fuel burning appliance are legally required to have carbon monoxide detectors," according to the Government of Yukon.

The territory's public guidance does not set out a placement rule for existing homes. Use the model-code standard as your floor, in each bedroom or within 5 m of each bedroom door, and confirm specifics with the Yukon Fire Marshal's Office.

Why the answer depends on your building and your municipality

Quebec does have a provincial CO alarm rule for existing buildings. It sits in the Building chapter of the Safety Code, enforced by the Régie du bâtiment du Québec, and it requires a CO alarm where a dwelling has a combustion appliance, such as a gas range or a fireplace, or direct access to an indoor parking garage.

The catch is scope. According to the RBQ's description of covered buildings, the residential buildings subject to the chapter are apartment and condominium buildings of more than two storeys and more than eight units, rooming houses with 10 or more rooms, hotels and motels, and private seniors' residences. Single-family houses and most plexes are not on that list.

For covered buildings, the duty dates to March 18, 2014, and sits with the building owner, according to a legal summary of the Safety Code changes.

Houses fall to municipal bylaws

For everyone else, the rule is local. Quebec municipalities can adopt stricter standards, and many have. Québec City is one example: its municipal regulation, mandatory since April 1, 2019, requires a CO alarm on each floor with a bedroom where there is a combustion appliance, or where a wall, floor or ceiling is adjacent to a room with one or to a parking garage, according to the Ville de Québec. It also bars installing the alarm inside the garage.

That rule applies in Québec City only. A house in Sherbrooke, Gatineau or Rimouski answers to its own municipality's bylaw, which may be stricter, looser or silent. New construction across the province follows the Quebec Construction Code, which mirrors the national 5 m bedroom rule and requires battery backup on electrically powered alarms.

Alberta: early on new homes, nothing for old ones

Alberta required CO alarms in new homes before most provinces did. They have been mandatory "for new builds, additions and alterations" since the province's 2006 building code took effect in 2007, but "the code is not retroactive, so older buildings ... do not require them," as CBC News reported in 2024. The province's Safety Codes Council recommends alarms in all existing homes anyway.

Manitoba: two signals that do not line up

Manitoba requires CO alarms in all new buildings, including private homes, hardwired and interconnected with the smoke alarms, under its building code since 2011.

For existing buildings, the current Manitoba Fire Code, in force since January 1, 2024, requires CO detection only in buildings that must undergo fire safety inspections by regulation, such as care homes, elderly housing, schools and daycares, where a CO risk exists. Battery-operated alarms are permitted there.

Here is the complication. In 2010, Manitoba announced it would require homeowners to retrofit CO detectors in all homes, including rentals, from April 2011, and national safety charity Parachute still lists Manitoba among jurisdictions with CO alarm legislation. The current Fire Code text does not carry a general duty for private houses. Until the province clarifies, treat a Manitoba house as unconfirmed, and install alarms regardless.

Prince Edward Island: announced, not confirmed

PEI's position is similar. In 2017, the province announced it would require CO detectors in all homes from January 2018, with fire codes updated to cover older houses. PEI now builds to the 2020 national codes, effective March 31, 2024. The regulation text applying that duty to existing private homes could not be located, and Parachute's national legislation tracker groups PEI with provinces that require CO alarms through building code adoption only.

Nova Scotia, New Brunswick, Newfoundland and Labrador, and the territories

The remaining jurisdictions follow the national template for new construction and renovations, with no province-wide retrofit duty for existing private homes identified. Nova Scotia adopted the 2020 national codes on April 1, 2025, New Brunswick on May 1, 2025, and the Northwest Territories on October 1, 2024. Newfoundland and Labrador moved straight to the 2025 edition on July 12, 2026. Nunavut remains on the 2015 edition.

The code-adoption dates come from the Canadian Board for Harmonized Construction Codes. In every one of these jurisdictions, an existing house with a gas furnace and no permit activity carries no CO alarm duty under provincial law.

Three questions, one answer

Placement rules vary, but they share a structure. Work through three questions and you land on a layout that satisfies the strictest rule in the country.

Question 1: Do you have a trigger? Look for any of these: a gas, oil or propane furnace or boiler; a gas or oil water heater; a gas range or dryer; a wood stove or any fireplace; an attached garage; or a suite sharing a wall or floor with a garage or a room holding a fuel-burning appliance. If yes, the law in your province likely requires an alarm in new construction, and in Ontario, Saskatchewan and Yukon, in your existing home too.

Question 2: Where do people sleep? Every rule in Canada anchors on sleeping areas. The national model says inside each bedroom, or within 5 m of each bedroom door measured along the hallway. Ontario says adjacent to each sleeping area. Federal guidance from Health Canada calls hallways outside sleeping areas "the most important place to install a carbon monoxide alarm," and notes that CO can only be detected by an alarm.

Question 3: How many storeys? Ontario now requires an alarm on every storey. No other province does for existing homes. It is still the right default everywhere, because the basement holding the furnace is often the storey with no alarm at all.

The most-protective layout

Combine the strictest version of each rule and you get a layout that is compliant in every Canadian jurisdiction:

Placement errors are where compliant homes still fail. Our guide to the placement mistakes homeowners make most often covers the dead-air corners, kitchens and furnace-room spots to avoid.

Who carries the duty when you rent

In the retrofit provinces, the duty in a rental sits with the owner. Ontario states it plainly: in rental homes, the landlord is responsible for complying with the Fire Code's CO alarm requirements. Saskatchewan places the duty on the building owner, and Quebec's Safety Code does the same for covered buildings.

Ontario spells out the landlord's side in the most detail. Landlords must install alarms to the Fire Code, keep them operating, maintain both primary and secondary power, and give tenants the manufacturer's maintenance instructions, according to the City of Toronto. Tenants must not disable an alarm, and must tell the landlord as soon as they know one is not working. Fines under Ontario's Fire Protection and Prevention Act reach $50,000 and/or a year in jail for an individual, and $500,000 for a corporation.

Apartments without a fuel source can still be covered

The multi-unit rules turn on adjacency, not just on what is inside the suite. In Ontario, a suite needs alarms if it contains a fuel-burning appliance or fireplace, if it sits directly above, below or beside a service room or a garage, or if it is heated by air from a fuel-burning appliance outside the unit. The service room holding the appliance gets an alarm of its own.

Saskatchewan's Henry's Law goes one step further from November 1: every residential suite, in every multi-unit building, regardless of what is next door.

A practical checklist for landlords in any province:

• Map every unit against the triggers: appliance in the unit, shared wall or floor with a garage or boiler room, heat from a central fuel-fired system.
• Record the manufacture date on every alarm, and schedule replacement before end of life.
• Test at tenancy turnover, and document it.
• Hand over the manufacturer's instructions at move-in.

For the testing and replacement routine that keeps those alarms reliable, see our guide to maintenance habits that keep smoke and CO alarms reliable.