Basement Egress Windows in Ontario: Code, Costs, and DIY vs Pro

DIY & Tutorials
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Egress windows are one of the most impactful basement improvements you can make. They bring in natural light, provide emergency exit, and are required by Ontario Building Code for legal sleeping rooms in basements.

Ontario Building Code Requirements

For a basement room to be legally classified as a sleeping room (bedroom), it must have:

  • Minimum net clear opening area of 0.35 m² (3.77 sq ft)
  • Minimum clear opening height of 600 mm (24")
  • Minimum clear opening width of 550 mm (22")
  • Maximum sill height of 1,000 mm (39") above the finished floor
  • Well-draining window well if below grade

These requirements come from OBC 9.7.4.5 — enforced during permit inspections for basement finishing projects.

Why Egress Windows Beyond Code Compliance

Even in non-bedroom spaces, egress windows dramatically improve basements:

  • Natural light transforms livability
  • Emergency exit capability
  • Better ventilation and air quality
  • Required for legal rental unit designation

Installation Process

  1. Engineering assessment (if cutting through foundation wall): Most residential basement walls require structural review before cutting.
  2. Permit application: Required for new window openings in foundation walls.
  3. Excavation: For below-grade installation — window well excavation, drainage gravel, window well liner.
  4. Lintel installation: Steel or concrete lintel spans the new opening.
  5. Window installation: Frame, window unit, waterproofing membrane at sill.
  6. Window well: Corrugated galvanized steel or polycarbonate covers standard.

Costs (GTA 2026)

  • Permit: $300–$600
  • Excavation (manual for tight access): $500–$1,200
  • Structural opening + lintel: $800–$1,500
  • Window supply and install: $600–$1,200
  • Window well and drainage: $400–$800
  • Total typical range: $2,500–$5,000 per window

When to DIY vs Hire

The foundation cutting and lintel work requires tools and skill most DIYers don’t have. The excavation is DIY-capable. Window well installation is straightforward DIY. The sensible split: hire for the structural work, DIY the well and gravel.

Share your egress window project at home.renovation.reviews — Ontario homeowners compare contractor quotes and DIY results in our Basement & Foundation section.

LF Builders handles basement egress window installations throughout the GTA.