What ceiling height is required in a basement in Ontario?
Ontario requires 2 100 mm of clear height over at least 75% of the basement floor area, with 1 950 mm permitted under beams and ducts.
Conditions and exceptions
- The 1 950 mm allowance applies at localised obstructions, not across the room.
- Finishing a basement into habitable space raises the requirement.
- A basement apartment is a secondary suite and is assessed under those rules instead.
Where this comes from
Ontario Building Code
This page states the requirement and points you to the publisher. It does not reproduce the code text — read the provision itself at the official source below.
Read the official text at Ontario — King's Printer →Verify this against the code edition actually adopted where you are building. Provinces, territories, and municipalities amend on their own schedules, and where the governing document and this page disagree, the governing document controls. This is not legal, engineering, or permitting advice. Last reviewed 2026-08-12.
Why the requirement is written this way
This page gives the figure. These notes explain the reasoning behind it and what it means on site.
Ask your own code question
Canadian Codes answers questions like this one from national, provincial, territorial, and municipal sources, and cites the document, section, and page so you can check it yourself.
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