Basement Egress Window Requirements
Last updated: June 2026
Minimum opening size, sill height, and well dimensions for emergency egress.
Detailed explanation
Bedrooms and some other rooms require an emergency egress window or door to the exterior. The opening must meet minimum area and dimension requirements so a firefighter with equipment can enter and occupants can exit.
The sill height above the floor is limited so occupants can reach the opening. Window wells are required where the bottom of the opening is below grade, with minimum projection and ladder or step provisions depending on depth.
Egress windows in basements are a common requirement when creating a legal bedroom or secondary suite. Existing windows may need enlargement or replacement.
Ontario Building Code references
Ontario Building Code
Section 9.9.10. — Egress windows or doors
Minimum opening area and dimensions.
Ontario Building Code
Section 9.9.10. — Window wells
Well size and access requirements.
Examples
- Adding a bedroom in the basement requires an egress window unless another compliant exit exists.
- A small existing basement window may need enlargement and a new well for compliance.
Common mistakes
- Assuming any operable window qualifies as egress.
- Window wells too small for required projection or ladder access.
- Sill height too high above the finished floor.
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