What egress window size does a Calgary basement suite need?

A basement bedroom in a Calgary suite requires an egress window with a minimum opening of 0.35 square metres (3.77 sq ft), with no single dimension less than 380mm (15 inches), and the sill height no more than 1,000mm (39 inches) above the finished floor. These are the minimums under the Alberta Building Code (National Building Code - 2023 Alberta Edition), and the City of Calgary enforces them on every secondary suite permit inspection.

The purpose of an egress window is straightforward — it's your emergency escape route if the stairway is blocked by fire or smoke. For a basement suite to be legal and safe, every bedroom must have its own qualifying egress window. A window that meets the opening size but sits too high on the wall (above 1,000mm from the floor) won't pass inspection because an occupant couldn't realistically climb out in an emergency.

The opening dimensions are the critical measurement — not the overall window frame size. The 0.35 sq m refers to the clear, unobstructed opening when the window is fully open. A slider window, for example, only opens half its total width, so you need to account for that when sizing your rough opening. Casement windows (crank-out style) are popular in Calgary basement suites precisely because the entire window swings open, making it easier to hit the minimum opening with a smaller frame.

Calgary-Specific Considerations

Calgary's deep frost line (1.2m+) and expansive clay soils mean window well installation needs careful attention. A proper egress window well must be large enough for a person to climb out — typically at least 900mm wide and deep enough to allow the window to fully open. The well needs drainage at the bottom (gravel base, often tied into the weeping tile system) to prevent water pooling against your foundation wall, which is a serious concern given Calgary's clay soils.

Window well covers are strongly recommended in Calgary — they keep out snow, debris, and the occasional curious animal, while still allowing emergency egress. Polycarbonate dome covers are common and don't require removal to exit.

Typical costs in Calgary for a basement egress window installation run $1,500–$3,500 per window, depending on the size of the cut, soil conditions, window well depth, and whether drainage work is needed. Homes on Calgary's expansive clay may require more excavation and drainage work, pushing costs toward the higher end.

Permits and Next Steps

A secondary suite requires a development permit and a building permit from the City of Calgary — egress windows are inspected as part of the building permit process. You'll also need electrical and HVAC permits if you're doing that work. Don't skip the permits; an unpermitted suite creates serious liability issues and can void your home insurance.

Your contractor will need to cut through the foundation wall (concrete block or poured concrete), install a properly sized window and frame, build and waterproof the window well, and ensure drainage is handled correctly. This is not a DIY project — foundation cutting requires specialized equipment and the work needs to pass a Safety Codes Officer inspection.

Browse licensed contractors in our directory at Calgary Construction Network to find experienced basement suite specialists in your area.