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Ontario Building Code Bedroom Egress Window Requirements

Egress window size in Ontario: 0.35 m2 opening, no side under 380 mm, 1,000 mm max sill, 550 mm window well clearance. Basement and bedroom rules.
minimum unobstructed open area
0.35 m²
minimum unobstructed open area
min width or height of the opening
380 mm
min width or height of the opening
max sill height above floor, not basements
1,000 mm
max sill height above floor, not basements
min clearance in front, in a window well
550 mm
min clearance in front, in a window well

Last updated

A bedroom egress window in Ontario must open from the inside without tools and give an unobstructed opening of at least 0.35 m², with no dimension less than 380 mm, held open without extra support (OBC Div. B 9.9.10.1.OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open…). Except in basements, its sill can be no higher than 1,000 mm above the floor, and a window opening into a window well needs 550 mm of clear space in front of it.

These rules matter most when finishing a basement bedroom, creating a secondary suite, or buying a house where a "den" is being marketed as a bedroom. This page explains Article 9.9.10.1. of the 2024 code in plain language. Local building departments enforce these rules and can add their own permit conditions, and existing buildings may be handled under Part 11, so ask before you cut a foundation wall.

Egress window values at a glance

Requirement Value Sentence
Unobstructed open area 0.35 m² minimum 9.9.10.1.(1)(b)
Smallest dimension of the opening 380 mm minimum 9.9.10.1.(1)(b)
How it opens from inside, without tools, stays open on its own 9.9.10.1.(1)(a), (c)
Sill height (not basements) 1,000 mm maximum above the floor 9.9.10.1.(2)
Clearance in a window well 550 mm minimum in front of the window 9.9.10.1.(3)
Window well cover openable from inside without keys, tools or special knowledge 9.9.10.1.(5)
Sliding windows the openable part must meet the minimums 9.9.10.1.(6)

This is our own summary of the article.

Where an egress window is required

9.9.10.1.(1)OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open… applies to every floor level that contains a bedroom in a suite. That floor level needs at least one outside window meeting the size and operation rules, unless a door on the same floor level as the bedroom gives direct access to the exterior. A walk-out basement with an exterior door on the bedroom level, for example, can rely on that door.

Note what the sentence says and does not say. It is written per floor level, not per bedroom. In practice many designers provide a qualifying window in each bedroom, and some municipalities expect that on permit drawings, so confirm with your building department before relying on a single window for the whole level.

The size rule, explained

Two tests apply at the same time:

  1. The open, unobstructed portion must be at least 0.35 m².
  2. Neither dimension of that opening (width or height) may be less than 380 mm.

So a 380 mm wide opening must be at least about 921 mm high to reach 0.35 m², and a 500 mm by 700 mm opening (0.35 m²) passes both tests. A 300 mm by 1,200 mm opening has 0.36 m² but fails, because 300 mm is under 380 mm.

"Unobstructed" means the clear opening when the window is open, not the rough opening or the glass size. Frames, sashes that do not swing clear, crank hardware and stops all reduce it. For sliding windows, only the part that actually opens counts (9.9.10.1.(6)OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open…). The window must also hold itself open: a casement that needs a prop does not meet Clause (1)(c).

Sill height

Outside basement areas, the window's sill may be no more than 1,000 mm above the floor (9.9.10.1.(2)OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open…). Basements are exempt from this limit, which recognizes that basement windows are usually high in the wall. Even so, a very high basement window is hard to climb out of, and some designers add a fixed step; ask your inspector how they treat that.

Window wells

When the window opens into a window well, there must be at least 550 mm of clearance in front of the window (9.9.10.1.(3)OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open…). If the sash swings toward the well, it must not reduce that clearance in a way that would restrict escape (9.9.10.1.(4)OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open…). Any protective cover over the well must open from the inside without keys, tools or special knowledge (9.9.10.1.(5)OBC Div. B 9.9.10.1. Egress Windows or Doors for Bedrooms(1) Except where a door on the same floor level as the bedroom provides direct access to the exterior, every floor level containing a bedroom in a suite shall be provided with at least one outside window that (a) is openable from the inside without the use of tools, (b) provides an individual, unobstructed open…). Window wells must also drain to the footing or another suitable location (9.14.6.3.OBC Div. B 9.14.6.3. Window Wells(1) Every window well shall be drained to the footing level or other suitable location.).

  • Glass area for light. Bedrooms and other rooms in a house also have minimum glass areas in Table 9.7.2.3, separate from the egress rule (9.7.2.3.OBC Div. B 9.7.2.3. Minimum Window Areas(1) Except as required in Article 9.9.10.1. and Sentence (3), the minimum window glass areas for rooms in buildings of residential occupancy or rooms that are used for sleeping shall conform to Table 9.7.2.3. (2) The unobstructed glass area of a door or skylight is considered equivalent to that of a window. (3) Work…).
  • Window guards. Upper-floor windows with low sills may need a guard or opening limiter (9.8.8.1.(4) and (5)OBC Div. B 9.8.8.1. Required Guards(1) Except as provided in Sentence (2) and except at the leading edge at the top of a flight, every surface to which access is provided, including but not limited to flights of steps and ramps, exterior landings, porches, balconies, mezzanines, galleries and raised walkways, shall be protected by a guard on each side…). A limiter that needs tools to release can conflict with the egress rule, which requires the window to open without tools, so plan the two rules together and ask your building department how they reconcile them.
  • Smoke alarms. Every bedroom also needs a smoke alarm. See smoke and CO alarms.

Common mistakes

  1. Counting the rough opening or glass size instead of the clear open area.
  2. Meeting the area but not the 380 mm minimum, typical with wide, short sliders.
  3. Casement windows that need a prop to stay open.
  4. A window well too shallow in front of the window, or a sash that swings into the 550 mm space.
  5. Locked or bolted window well grates.
  6. Labelling a basement room a bedroom without checking egress, ceiling height and alarms together.

How to look it up yourself

In Division B, Part 9 of the 2024 Compendium, Section 9.9 is "Means of Egress". Search for:

  • "Egress Windows or Doors for Bedrooms"
  • "unobstructed open portion"
  • "window well"
  • "maximum sill height"

The answer is almost always in one article, 9.9.10.1., so read all seven sentences.

Means of egress (Section 9.9) is its own section of the House exam syllabus. Read the free House exam study guide and try the free practice quiz on that page.

Based on the official 2024 Building Code Compendium on ontario.ca.

© King's Printer for Ontario, 2024. Reproduced with permission.

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Frequently asked questions

What size does a bedroom egress window have to be in Ontario?
It must provide an individual, unobstructed open portion of at least 0.35 m2, with no dimension less than 380 mm, and stay open without extra support (Division B, Sentence 9.9.10.1.(1)).
Does every bedroom need its own egress window?
The 2024 wording requires at least one qualifying window on every floor level containing a bedroom in a suite, unless a door on the same floor level as the bedroom gives direct access to the exterior (Division B, Sentence 9.9.10.1.(1)). Many designers still put one in each bedroom, and your building department may expect it, so check locally.
What is the maximum sill height for an egress window?
1,000 mm above the floor, except in basement areas (Division B, Sentence 9.9.10.1.(2)).
How much space is needed in front of a basement egress window in a window well?
At least 550 mm of clearance in front of the window. A sash that swings into the well must not reduce that clearance in a way that would restrict escape (Division B, Sentences 9.9.10.1.(3) and (4)).
Can I put a cover over the window well?
Yes, but the cover must be openable from the inside without keys, tools or special knowledge (Division B, Sentence 9.9.10.1.(5)).
Do sliding windows count?
Yes, as long as the openable portion itself meets the 380 mm minimum dimension and the 0.35 m2 area (Division B, Sentence 9.9.10.1.(6)).