If you are finishing a basement in Ontario and the plan includes a bedroom, the Ontario Building Code requires an egress window in that room. This is not a suggestion and it is not waived by inspectors. Here is a plain-language explanation of what the code requires and what the installation process involves.
What the code requires ¶
Section 9.9.10 of the Ontario Building Code specifies that every bedroom must have at least one window that can be opened from the inside without tools, with a minimum unobstructed opening of 0.35 sq m (approximately 3.8 sq ft), a minimum opening width of 380mm (15 inches), and a minimum opening height of 380mm (15 inches). The sill height must be no more than 1,000mm (39 inches) above the finished floor. In a basement, existing windows are almost never large enough to meet these requirements, which means enlarging the opening in the foundation wall.
What the installation involves ¶
Enlarging a basement window opening requires cutting through the foundation wall, which in most Toronto homes built before 1970 is poured concrete or concrete block. The process involves marking the new opening, cutting with a concrete saw or core drill, installing a lintel above the opening to carry the load, and then installing the new window unit. The exterior well (the recessed area outside the window) is typically lined with a prefabricated plastic or galvanized steel well and filled with gravel for drainage. The work takes one to two days per window.
Permit and inspection requirements ¶
Enlarging a window opening in a foundation wall requires a building permit in Toronto and most GTA municipalities. The permit application includes a drawing showing the window location, size, and lintel specification. The inspector will check the window size and operability during the framing inspection. We include egress window work in the basement finishing permit application so there is one permit covering the full scope of work.
Cost and timeline ¶
The cost to enlarge a basement window opening and install a code-compliant egress window in Toronto typically runs $1,800 to $3,200 per window, depending on foundation type and exterior grade conditions. Poured concrete foundations cost more to cut than block foundations. The work is typically done early in the project, before framing, so the opening can be properly integrated into the wall assembly.
If your basement finishing plan includes a bedroom, budget for at least one egress window and factor the permit process into your timeline. We handle the permit application and the installation as part of the basement finishing scope. Reach us to schedule an estimate if you want to discuss the specifics of your space.