One of the most misunderstood aspects of basement suite legalization in Ontario is the egress window requirement. I went through this process last year and want to clarify what’s actually required.
Ontario Building Code requirements for egress windows in sleeping areas:
- Minimum opening area: 0.35 m² (3.77 sq ft)
- Minimum opening height: 380mm (15 inches)
- Minimum opening width: 450mm (17.7 inches)
- Maximum sill height from floor: 1,000mm (39.4 inches)
These apply to every bedroom in a basement suite, plus the suite must have an emergency escape from a common area if the bedroom windows face a hazard.
The installation process:
- Cut through foundation wall (requires structural consideration)
- Install window well with drainage if below grade
- Frame the opening with proper lintel/header
- Install egress-rated window
- Inspection required before drywall
Cost in Toronto/GTA (2025–2026):
- Basic egress window installation: $2,500–$4,500 per window
- With window well and drainage: $3,500–$6,000
- If underpinning or excavation needed: higher
Common mistake: Installing a window that meets the size requirements but is positioned too high, exceeding the 1,000mm sill height limit. The inspector will catch this.
Discuss your specific situation at home.renovation.reviews — there are threads from homeowners in Toronto, Mississauga, and other GTA municipalities who’ve gone through the legalization process.