What size egress window do I need in a basement bedroom?
Last updated: June 2026
Detailed explanation
Bedrooms require emergency egress to the exterior unless another compliant exit is available. The openable portion of the window must meet minimum width, height, and area.
The sill cannot be too high above the floor — limiting height makes the opening usable in an emergency. When the bottom of the opening is below grade, a window well with minimum size and access is required.
Existing basement windows often need enlargement, well excavation, and drainage when converting to a bedroom or secondary suite.
Relevant OBC sections
Ontario Building Code
Section 9.9.10. — Egress windows or doors
Example scenario
You want a fourth bedroom in the basement. The existing 24×16 inch slider is too small — you plan a new casement egress unit and a 1,500 mm deep window well with steps.
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