Ontario’s New Carbon Monoxide Alarm Rules: What Changed, What’s Required, and What Homeowners Should Do

Carbon monoxide safety isn’t new — but Ontario’s rules around it have changed, and the update is catching a lot of homeowners off guard.

If you’ve owned your home for a while, there’s a good chance your current setup was perfectly acceptable under the old requirements. That doesn’t automatically mean it meets today’s standard.

Below is the clean, homeowner-friendly breakdown: old rules vs. new rules, plus a simple “do this now” checklist so you can get compliant without stress.

🔙 The Old Requirements (What Many Homes Still Have)

Under the previous rules, carbon monoxide (CO) alarms were generally required outside sleeping areas — and typically only in homes where CO was more “obvious” (like a gas furnace or fireplace).

In real life, that meant many homes ended up with:

• One CO alarm near the bedrooms
• No CO alarm on the main floor (if bedrooms were upstairs)
• No CO alarm in the basement (if there were no bedrooms down there)

🔄 The New Requirements (What Changed)

The updated Ontario Fire Code requirements expand both where alarms must be installed and which homes are affected.

🏡 Does This Apply to Your Home?

If your home has any of the following, you should assume these requirements apply and verify your setup:

• A fuel-burning appliance (gas/oil/propane furnace, water heater, etc.)
• A fireplace (including fuel-burning units)
• An attached garage (this is the big one most homeowners miss)

🚗 Why the Attached Garage Rule Matters

This is the part that surprises people: even if your home is “mostly electric,” an attached garage can still be a carbon monoxide risk.

CO can enter the home from a vehicle warming up, gas-powered equipment, or exhaust that migrates through shared walls and ceilings. And because CO is invisible and odourless, alarms are the only reliable warning system.

✅ What Homeowners Should Do (Simple Checklist)

1. Do a quick walkthrough — storey by storey.
   Basement included. If you have 3 levels, think “3 alarms minimum,” plus the sleeping-area placement.
2. Confirm you have a CO alarm adjacent to each sleeping area.
   The goal is simple: if it goes off at night, it needs to be loud enough to wake you up.
3. Add an alarm on every storey that doesn’t already have one.
   Main floor and basement are the two most common misses.
4. Use approved alarms and follow the manufacturer’s instructions.
   CO mixes with air differently than smoke, so follow the placement guidance on the device.
5. Test monthly, and replace old units when they expire.
   Many alarms have a service life (often 5–10 years). If yours is outdated, swap it.

🏠 Why This Matters for Resale (Even If You’re Not Moving Today)

I see CO alarms come up most often during home inspections, insurance reviews, and pre-listing walkthroughs. Missing or incorrectly placed alarms can trigger last-minute fixes and unnecessary negotiation friction.

The good news? This is one of the easiest compliance updates you can do as a homeowner — and it’s the kind of small detail that protects both your family and your future sale.

📌 Bottom Line

The shift is simple: the old setup was often “near bedrooms.” The new standard is “near bedrooms + every storey” — and attached garages are now a major trigger.

If you want a second set of eyes before you list, renovate, or just to make sure you’re covered, reach out. I’d rather help you catch it early than have it show up as a surprise later.