What size egress window is required in a Calgary basement bedroom?

The Alberta Building Code requires every basement bedroom egress window to have a minimum unobstructed opening of 3.77 square feet (0.35 square metres), a minimum width of 15 inches (380 mm), and a maximum sill height of 39 inches (1,000 mm) from the finished floor. These dimensions refer to the actual clear opening when the window is fully open — not the frame size, not the glass size, but the space a person can physically pass through in an emergency.

Understanding the difference between window frame size and actual egress opening is critical when shopping for windows. A window advertised as 36 by 24 inches may not provide 3.77 square feet of unobstructed opening once you account for the frame, hardware, and opening mechanism. Casement windows (hinged on one side, swinging outward) are the most popular choice for Calgary basement egress because the entire sash opens, maximizing the clear opening relative to the frame size. A casement window with a 30-by-20-inch clear opening provides 4.17 square feet — comfortably above the minimum. Sliding windows can also work but typically need to be larger overall since only half the window opens at a time.

The 39-inch maximum sill height ensures that occupants, including children, can reach the window opening from the floor. This measurement is from the finished floor — so if you're adding a subfloor system (which adds three-quarters of an inch) plus LVP flooring (another quarter inch), your effective sill height drops by about an inch. Plan accordingly, especially in older Calgary homes where existing window openings may already be positioned high on the wall. In homes built in the 1960s through 1980s in neighbourhoods like Dalhousie, Woodbine, and Canyon Meadows, original basement windows are often too small and too high to meet current egress requirements.

The window must open fully without tools, keys, or special knowledge, and it must remain open on its own without being held. This rules out any window that requires a prop or that slowly closes under its own weight. Safety Codes Officers will test this during inspection — if the window doesn't stay open, it fails.

Calgary's climate adds practical considerations beyond code minimums. Egress windows are larger openings in your foundation wall, which means more potential for heat loss during our -30 degree winter nights and more exposure to wind-driven rain and snowmelt. Invest in high-quality, double-paned, low-E windows rated for Calgary's climate zone. The upfront cost difference between a budget window and a quality unit is typically $200 to $400, but the energy savings and condensation prevention pay for themselves within a few years. Find experienced basement contractors through the Calgary Construction Network to ensure your egress windows meet code and perform well in our climate.