The Ontario Fire Code is strict and specific about smoke and CO detectors in homes. Here’s the practical summary — not the lawyer version.
What the code requires
- A smoke alarm on every storey, including basements.
- A smoke alarm outside every sleeping area (hallway between bedrooms).
- A CO alarm outside every sleeping area if the home has a fuel-burning appliance (gas furnace, gas water heater, wood stove, fireplace) OR an attached garage.
- All alarms must be interconnected in new builds and substantial renovations — when one trips, they all sound.
- Hardwired with battery backup for new builds. Battery-only is grandfathered for older homes but interconnected hardwired is the gold standard.
What most homeowners get wrong
- Battery-only alarms past their replacement date — both smoke and CO alarms have a 10-year lifespan (look for “replace by” date on the back). Expired alarms test fine on the button but don’t actually detect.
- No CO alarm at all in homes with gas appliances — surprisingly common in older homes that added a gas furnace later.
- Only one smoke alarm on the main floor and none upstairs — needs to be one per storey plus one outside bedrooms.
- Alarms in the kitchen — not required by code and frequently trip from cooking. Use a heat alarm in the kitchen instead, smoke alarms in adjacent hallways.
Combination smoke + CO alarms
One device, dual sensor. Code-acceptable — saves an alarm in each location. We install Kidde combination units with voice alerts (“Fire” or “Carbon monoxide”) so you know what to do at 3am.
When to call us
- Your alarms are battery-only and you want to upgrade to hardwired interconnected.
- Any alarm in your home is more than 10 years old.
- You’re renovating — new code applies to the renovated area.
- You have gas appliances or an attached garage and no CO alarm.
See our smoke and CO detector page for installed pricing.