Smoke Alarm Requirements for Dwellings
Last updated: June 2026
Location, interconnection, and power requirements for smoke alarms in homes.
Detailed explanation
Smoke alarms are required on every storey and outside sleeping areas in dwelling units. When one alarm activates, all alarms in the dwelling must sound if more than one is required.
New construction and substantial renovations typically require hardwired alarms with battery backup. Replacement and maintenance rules apply to existing homes.
Carbon monoxide alarms are required near sleeping areas when the dwelling contains a fuel-burning appliance or attached garage.
Ontario Building Code references
Ontario Building Code
Section 9.10.19. — Smoke alarms
Location and interconnection.
Ontario Building Code
Section 9.33.4. — Carbon monoxide alarms
CO alarm requirements.
Examples
- A two-storey house needs alarms on both floors and near bedrooms.
- Adding a secondary suite requires alarms that alert occupants in both units.
Common mistakes
- Installing only one smoke alarm in a multi-storey home.
- Non-interconnected battery alarms where interconnection is required.
- Placing alarms too close to kitchens or bathrooms causing nuisance trips.
Have a specific question?
Ask Tenet for a source-backed answer tailored to your project.