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OBC DIVISION B · PART 9 · SECTION 9.9 — MEANS OF EGRESS

What size does a bedroom egress window need to be in Ontario?

Unless the bedroom has a door to the exterior or the dwelling is sprinklered, each bedroom needs a window openable from the inside without tools, providing an unobstructed opening of at least 0.35 m² with no dimension less than 380 mm.

Code reference — verbatim
Except where the suite is sprinklered or the bedroom has a door leading directly to the exterior, each bedroom shall have at least one outside window that is openable from the inside without the use of tools, provides an individual, unobstructed open portion having a minimum area of 0.35 m² with no dimension less than 380 mm, and maintains the required opening without the need for additional support. Where the window opens into a window well, a clearance of not less than 760 mm shall be provided in front of the window.
OBC Division B, Subsection 9.9.10. (Egress Windows or Doors for Bedrooms)
What this means in practice

The two-number test trips people up: 0.35 m² of area AND no dimension under 380 mm — a wide, short awning opening can hit the area target and still fail the dimension test, and a casement window's opening is measured to the open sash, which can cut the clear width roughly in half. The window must hold itself open (a crank-out casement qualifies; a heavy single-hung that slams shut does not, unless fitted to stay open). Basement bedrooms are where this requirement bites hardest: the window well needs 760 mm of clearance, and if the well is deeper than 600 mm it effectively needs a means to climb out. Sill height above the floor matters for usability and is capped for new construction.

Plain language

Every bedroom needs a window a person can climb out of during a fire: about the size of a large pizza box in area, no side narrower than 15 inches, openable by hand, and it must stay open on its own. In basements, add a window well roomy enough to actually stand in.

Related questions

What is the minimum bedroom size in Ontario?What is the minimum ceiling height in Ontario?

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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.