← Ontario Building Code FAQ
OBC DIVISION B · PART 9 · SECTION 9.10 — FIRE PROTECTION

What separation is required between an attached garage and the house in Ontario?

An attached garage must be separated from the dwelling by a continuous gas-tight barrier that blocks exhaust fumes. Any door between them must be weatherstripped and self-closing, and may not open into a bedroom.

Code reference
Where a storage garage is attached to or built into a dwelling, the wall and ceiling assemblies between them must provide an effective airtight barrier to prevent carbon monoxide and gasoline vapours from entering the dwelling. Doorways between the garage and dwelling require tight-fitting, weatherstripped, self-closing doors and must not lead directly into a sleeping room.
OBC Division B, Article 9.10.9.16.

Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.

What this means in practice

For a single dwelling and its own garage, this is primarily a gas-tightness requirement, not a fire-resistance rating; drywall taped continuously behind any furring, sealed penetrations, and sealed rim joist areas achieve it. Every duct, wire and pipe passing through must be sealed, and ducts serving the garage cannot connect to the house system. The self-closer on the man-door is a frequent inspection deficiency, as is a mudroom door removed by homeowners later. Garages serving multiple suites face true fire-separation ratings instead.

Plain language

The wall between your garage and house must be sealed airtight so car exhaust can't seep into living spaces, and the connecting door must close itself automatically. That door is never allowed to open into a bedroom.

Related questions

What fire separation does a basement apartment need in Ontario?Where are smoke alarms required in a house in Ontario?When are carbon monoxide alarms required in Ontario homes?

Get answers like this for any code question

BUILDAiD Assist searches the building code and answers in plain English with exact citations — in seconds.

Try BUILDAiD Beta

This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.