Want a Legal Basement Rental? Start With This Window: Ontario Egress Window Size Requirements Explained
Turning a basement into a rental bedroom without a compliant egress window may be illegal. The Ontario Building Code sets hard numbers for openable area, minimum dimension, and the window well
How big must a basement bedroom’s egress window be, and can you rent without one?
A bedroom must have a direct exterior egress door or window; without one it’s generally non-compliant and can’t be rented as a legal bedroom. According to the Ontario Building Code, a room used as a bedroom needs an egress window (unless it has a door leading directly outside). The hard numbers: a minimum unobstructed openable area of 0.35 m², with no dimension less than 380 mm; and where the window opens into a window well, at least 550 mm of clearance in front of it. These are the baseline for fire escape and rescue entry.
Source: Ontario Building Code (egress window/door provisions: a bedroom requires an egress window; minimum openable area 0.35 m², minimum dimension 380 mm; 550 mm window-well clearance). Reviewed June/July 2026.
More owners want to carve a bedroom out of the basement to help with the mortgage, and the first trap I keep seeing is the window — many old basement windows are small and high and simply don’t meet egress requirements, making a rented bedroom both unsafe and illegal. The Ontario Building Code sets explicit numbers for openable area, minimum dimension, and window-well clearance. Here’s how big an egress window must be, what else a legal basement bedroom requires, and how a landlord should verify it — before an incident or an inspection forces the issue.
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Why the egress window is a hard requirement
⚠️A basement bedroom without a compliant egress window is unsafe and illegal to rent. This is a hard fire-escape requirement, not a skippable finishing item. Before renting a room as a bedroom, confirm the egress window (or a direct exterior door) meets code.
The dimensions: openable area, minimum side, window well
ℹ️The egress window is only the entry condition for a legal basement bedroom. Ceiling height, area, alarms, and second-unit separation/fire/sound/electrical plus municipal registration must all be met. Verify the whole plan against the Ontario Building Code and local rules — don’t fixate on one window.
More than one window: other legal basement bedroom conditions
How a landlord verifies: drawings, permits, inspection
The cost of non-compliance + sale considerations
Frequently Asked Questions
What’s the minimum size for a basement bedroom egress window?
According to the Ontario Building Code, an egress window needs a minimum unobstructed openable area of 0.35 m² with no dimension less than 380 mm; where it opens into a window well, at least 550 mm of clearance in front of it.
Can a basement without an egress window be rented as a bedroom?
Generally no. A bedroom needs an egress window or a door directly outside — a hard safety requirement under the Ontario Building Code. Without it, it isn’t a legal bedroom, and renting it carries safety and compliance risk; upgrade it to code first.
Do I need a permit to cut in a compliant egress window?
Usually yes. Cutting in an egress window often involves digging a window well and cutting the foundation wall — structural work that needs a building permit and municipal inspection, done by professionals with records kept for renting, insurance and resale.
Does having an egress window make a basement bedroom legal?
Not by itself. The egress window is the entry threshold; a legal basement bedroom/second unit also needs ceiling height, area, light/ventilation, smoke/CO alarms, separation/fire/sound/electrical and municipal registration — verify each item.
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