What is the maximum sill height for an egress window in an Ontario basement bedroom?

The Ontario Building Code sets the maximum egress window sill height at 44 inches (1,100 millimetres) measured from the finished floor to the bottom of the window opening. This measurement is taken from the floor surface directly below the window, not from the concrete slab before flooring is installed — so you need to account for any subfloor system or flooring thickness you plan to install when planning your egress window placement.

This 44-inch maximum exists for a critical life-safety reason: in a fire or emergency, a person — including a child — must be able to reach and climb through the window to escape. If the sill is any higher, escape becomes significantly more difficult, especially in a smoke-filled room where visibility is zero and panic sets in. The City of Toronto Building Division enforces this requirement strictly during inspections, and your basement bedroom will not pass final inspection if the sill height exceeds this maximum.

Beyond the sill height, the egress window must also meet minimum opening size requirements under the Ontario Building Code. The unobstructed opening must be at least 3.77 square feet (0.35 square metres) with a minimum width of 15 inches (380 millimetres). The window must open without tools or special knowledge — casement and slider styles are the most common choices for basement egress windows in GTA homes. Awning-style windows, which are common in older Toronto basements, almost never meet egress requirements because their opening geometry is too restrictive.

For many older GTA homes — particularly the post-war bungalows across Scarborough, North York, and Etobicoke built between 1945 and 1975 — the existing basement windows are far too small to meet egress requirements. These homes typically have narrow, horizontal slider windows set high in the foundation wall. Converting a basement room into a legal bedroom in these homes means cutting a larger opening in the foundation wall, which is structural work requiring an engineer's involvement and a building permit. In pre-war homes across established neighbourhoods like Cabbagetown, Riverdale, or the Annex, low ceiling heights can make the sill height measurement even more challenging, since the window may need to be positioned lower in the wall to stay under 44 inches from a raised finished floor.

The window well on the exterior is equally important. It must be large enough to allow a person to escape and for firefighters to access the window. If the window well is deeper than 24 inches below grade, a permanently attached ladder or steps are required. The window well must also have proper drainage to prevent water from pooling against the window — a common issue in GTA clay soils where water drains slowly.

Expect to pay $3,000 to $8,000 per egress window installed in a GTA home, including cutting the foundation wall, installing the window and frame, building the window well, and restoring the exterior. If you are finishing a basement bedroom, this is a non-negotiable expense. A room without a compliant egress window cannot legally be marketed or used as a bedroom, and more importantly, it puts occupants at genuine risk in a fire.