Ontario changed the rules in January. Most homes now need more alarms.
The carbon monoxide alarm rules in the Fire Code were updated on January 1, 2026. Here is what your Alliston home needs now.
100% satisfaction guarantee
Quick answer
Ontario's carbon monoxide alarm rules changed on January 1, 2026. An existing home now needs an alarm adjacent to each sleeping area and on every storey, including storeys with no bedrooms. The rules apply if the home has a fuel-burning appliance, a fireplace, or an attached garage.
Key takeaways
- The every-storey requirement is the new part. Alarms near bedrooms were already required; alarms on floors without bedrooms were not.
- An attached garage triggers the rules on its own, even in a house with no gas appliance at all.
- Health Canada notes carbon monoxide has no smell, no taste and no colour. An alarm is the only way to know it is there.
- A smoke alarm will not detect it. The two devices sense completely different things.
- If the alarm sounds, everyone leaves the house first and calls 911 from outside. No exceptions, no investigating.
What changed in Ontario's carbon monoxide alarm rules?
On January 1, 2026, updated Fire Code requirements took effect, bringing Ontario in line with the 2020 National Fire Code of Canada. The headline change for homeowners is placement. An alarm is now required on every storey of the home, not only adjacent to the sleeping areas. The rules cover existing houses, semi-detached homes, townhouses and cottages.
Ontario has required carbon monoxide alarms in homes since the Hawkins-Gignac Act, named for a Woodstock family who died of carbon monoxide poisoning in 2008. The January 2026 update does not replace that requirement. It widens it.
Which Alliston homes need a carbon monoxide alarm?
Four things trigger the requirement, and a home needs only one of them. A fuel-burning appliance such as a furnace, water heater or stove running on gas, propane, oil or wood. A fireplace. An attached garage. Or heating air drawn from a fuel-burning appliance located outside the home, such as in a utility shed.
The attached garage trigger catches people out. A family with baseboard heating, an electric water heater and no gas line still falls under the rules. A vehicle idling in an attached garage puts carbon monoxide directly against the house.
Where exactly do the alarms have to go?
Two placement rules apply together, and meeting one does not satisfy the other. Section 2.16 of Division B of the Fire Code requires an alarm adjacent to each sleeping area, meaning near all bedrooms. It also requires one on every storey, including storeys with no sleeping area at all.
| Part of the home | Alarm required? | Why |
|---|---|---|
| Hallway outside the bedrooms | Yes | Adjacent to a sleeping area |
| Basement, no bedrooms | Yes | Every storey, and usually where the furnace lives |
| Main floor, no bedrooms | Yes | Every storey |
| Second floor with bedrooms | Yes | Both rules at once |
| Attached garage itself | Follow the manufacturer | The garage triggers the requirement for the house; it is not where the alarm protects you |
A common Alliston layout — two storeys over a finished basement, bedrooms upstairs — needs at least three alarms under the current rules. Many homes that were fully compliant in 2025 have one.
What does carbon monoxide do to you?
Health Canada describes carbon monoxide as having no smell, no taste and no colour, which is why it is often called the silent killer. Mild exposure causes tiredness, headaches and shortness of breath. Severe exposure causes loss of consciousness, coma and death. Health Canada states plainly that anyone is at risk.
The mild symptoms are the dangerous part, because they look like a winter cold or simple fatigue. One useful test: if several people in the house feel unwell at once and improve after going outside, treat that as a carbon monoxide concern rather than a bug going around.
What should you do when the alarm sounds?
Get everyone out of the house first, into fresh air, and call 911 from outside. Do not open windows to clear the air, do not look for the source, and do not go back in to check the furnace. Emergency services carry meters and can tell you when the house is safe to re-enter.
Safety first
If a carbon monoxide alarm sounds: get everyone outside into fresh air, then call 911 from outside. Do not investigate the source yourself and do not re-enter until emergency services say it is safe.
If you smell a rotten egg or sulphur odour: that is a natural gas leak, not carbon monoxide. Leave the area immediately. From a safe distance, such as a neighbour's home, call the Enbridge Gas 24-hour emergency line at 1-866-763-5427 or 911. Do not use phones or electronics near the leak and do not switch anything on or off.
Never open the furnace cabinet, touch gas lines, burners or the gas valve, bypass a safety switch, or handle refrigerant. That work is regulated for a reason.
How does a furnace end up producing carbon monoxide?
Two ways: the burner stops burning cleanly, or the exhaust cannot get out of the house. A cracked heat exchanger lets combustion gases into the air stream. A blocked, disconnected or snow-buried vent pushes exhaust back inside. Health Canada also lists fireplaces, wood and pellet stoves, gas stoves and gas dryers as household sources.
This is the practical argument for an annual inspection. A heat exchanger crack is not something a homeowner can see, and the first reliable sign is often the alarm itself. Our guide to signs your furnace needs repair before winter covers the warning signs that are visible from outside the cabinet.
What we see in Alliston homes
Attached garages and century homes pull in opposite directions
Alliston and the wider New Tecumseth area have grown quickly, and the newer subdivisions are full of two-storey homes with attached garages over finished basements. That layout triggers the carbon monoxide alarm rules twice over and usually needs three alarms. It is also the layout most likely to have exactly one, installed years ago in the upstairs hallway.
Downtown Alliston runs the other way. Century homes often have a furnace added to a building that never had ductwork, a chimney shared with a water heater, and sometimes a wood stove still in use. More fuel-burning appliances in an older building means more places for combustion gases to go wrong.
Then there is snow. High-efficiency furnaces vent through plastic pipes that end on an outside wall, usually low. When drifting snow buries them the furnace normally locks out on a safety switch, which is the system working correctly. The risk is a vent that is partly blocked rather than fully buried, because the furnace keeps running.
Aire One Barrie serves Alliston, Angus, Cookstown, Essa, Thornton and the rest of Simcoe County. The Alliston heating and cooling page has the full service list.
How often should you test and replace the alarm?
Test every alarm monthly using its test button, and replace the battery on the schedule in the manual. Carbon monoxide sensors also wear out: most units carry an expiry date printed on the back, typically seven to ten years from manufacture depending on the model. An expired alarm can pass its own button test and still fail to detect gas.
The check worth doing today
Take the alarms off the wall and look at the back. If there is no date, or the date has passed, replace the unit. Then count your storeys and count your alarms. If the second number is smaller, you are short under the current rules.
The short version
Ontario's carbon monoxide alarm rules now ask for an alarm adjacent to every sleeping area and one on every storey. A fuel-burning appliance, a fireplace or an attached garage brings a home under them. Count your floors, check the expiry dates, and book the furnace inspection that catches the problem before the alarm has to.
Talk to Aire One Barrie
Licensed technicians, free detailed estimates with the price before work starts, and 24/7 emergency service across Alliston and Simcoe County. Furnaces, boilers, heat pumps, air conditioners, water heaters and indoor air quality.
- Carrier Factory Authorized Dealer — Comfort, Performance and Infinity series
- Rent or buy options on furnaces, air conditioners and water heaters
- 100% satisfaction guarantee
Frequently asked questions
Do I need a carbon monoxide alarm if my house is all electric?
Possibly. Ontario's rules are triggered by a fuel-burning appliance, a fireplace, an attached garage, or heating air drawn from a fuel-burning appliance outside the home. An all-electric house with an attached garage still needs alarms, because a vehicle running in the garage is a carbon monoxide source.
How many carbon monoxide alarms does an Ontario home need?
The Fire Code sets placement rather than a number. You need one adjacent to each sleeping area, and one on every storey of the home, including storeys with no bedrooms. A two-storey house with a basement and bedrooms on one floor therefore needs at least three.
Can I put the alarm anywhere on the floor or the ceiling?
Follow the manufacturer's instructions on the box. Carbon monoxide mixes fairly evenly with air rather than rising or sinking the way some gases do, so manufacturers specify different mounting heights for different models. The legal requirement is which rooms and storeys, not the exact height.
Will a smoke alarm detect carbon monoxide?
No. A smoke alarm senses particles from combustion. A carbon monoxide alarm senses the gas itself, which Health Canada notes has no smell, no taste and no colour. Combination units exist and satisfy both requirements, but a plain smoke alarm does not.
What makes a furnace start producing carbon monoxide?
Incomplete combustion, or exhaust that cannot leave the house. A cracked heat exchanger, a blocked or disconnected vent, snow covering the outside vent terminals, or a burner that is not firing cleanly can all do it. This is why an annual inspection by a licensed technician matters more than any single warning sign.
Sources
- Technical Standards and Safety Authority — Changes to the Ontario Fire Code: new requirements for CO alarms (effective January 1, 2026)
- Government of Ontario — Fire Code, O. Reg. 213/07, Section 2.16 of Division B
- Health Canada — Carbon monoxide infographic
- Legislative Assembly of Ontario — Hawkins Gignac Act (Carbon Monoxide Detectors)
- Enbridge Gas — Ontario emergency contact and gas leak instructions
