Minimum Ceiling Heights in Dwellings
Last updated: June 2026
Part 9 minimum ceiling heights for habitable rooms, basements, and stairs.
Detailed explanation
Habitable rooms in dwelling units require minimum ceiling heights measured from finished floor to finished ceiling. Bathrooms, closets, and some sloped-ceiling areas have exceptions.
Basement ceiling height is a frequent issue in secondary suite projects. Beams, ducts, and structure may reduce height below the minimum in portions of a room if the code allows limited encroachment.
Stairways and under-stair spaces have separate headroom requirements that differ from general room heights.
Ontario Building Code references
Ontario Building Code
Section 9.5.3. — Ceiling heights
Minimum heights in dwelling units.
Ontario Building Code
Section 9.5.2. — Headroom
Headroom in exits and under obstructions.
Examples
- A basement suite living room must meet minimum height except where beams encroach within limits.
- Finished attic bedrooms with sloped ceilings must meet height at the room center and near walls.
Common mistakes
- Measuring before final floor and ceiling finishes are accounted for.
- Assuming low basement height is grandfathered for a new suite without verification.
- Duct soffits that reduce height below allowed encroachment limits.
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