Fire Separation for Basements and Suites
Last updated: June 2026
Required fire-resistance ratings between units, garages, and furnace rooms.
Detailed explanation
Fire separation is provided by assemblies (walls, floors, doors) with a fire-resistance rating measured in minutes. Secondary suites require separation between the suite and the remainder of the house.
Furnace and utility rooms may need fire separation depending on fuel type and location. Shared exits and stair enclosures must maintain continuity of separation without unprotected openings.
Doors in fire separations must be self-closing and may require a minimum fire-protection rating. Penetrations for pipes and ducts need approved fire-stopping.
Ontario Building Code references
Ontario Building Code
Section 9.10.22. — Secondary suites
Fire separation between suite and house.
Ontario Building Code
Section 9.10.15. — Fire separations
General fire separation requirements.
Examples
- A basement apartment needs rated separation on shared walls and ceilings with the main floor.
- An open stair between units without an enclosed rated shaft may not comply for a secondary suite.
Common mistakes
- Using regular drywall where a rated assembly is required.
- Hollow-core doors in required fire separations.
- Unsealed pipe and duct penetrations through rated walls.
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