Minimum clear opening area
At least 0.35 square metres, approximately 3.77 square feet or 542 square inches.
London & Southwestern Ontario
Basement egress windows built around Ontario code.
EliteCraft specializes in basement egress window projects and also supplies and installs replacement windows, entry doors and patio doors.
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Egress window specialistsCode-focused planningFree project quotes
Ontario egress specifications
Does your basement opening meet the requirements?
The rule is based on the actual clear opening with the window fully open. Frame size, glass size and rough-opening size do not determine compliance.
Minimum opening dimension
No clear-opening height or width can be less than 380 mm, approximately 15 inches.
Opens from inside
The window must open from inside without tools and remain open without extra support.
Window-well clearance
A window opening into a well needs at least 550 mm of clear space in front of the opening.
Sill height above the floor
The 1,000 mm maximum applies outside basement areas. Basement areas are excepted from this specific limit.
Out-swinging sash
A sash swinging toward the well cannot reduce the required clearance or restrict emergency escape.
Window-well cover
A protective cover must open from inside without keys, tools or special knowledge of the mechanism.
Sliding windows
Only the openable portion counts. The fixed side of a slider is not part of the clear opening.
Important: Ontario generally requires at least one compliant outside window on each floor level containing a bedroom, unless a door on that same level provides direct access outside. It does not necessarily mean one egress window in every bedroom.
Quick opening check
Enter the clear opening size
Measure only the unobstructed opening when the window is fully open.
Enter a width and height to check the clear opening.
This calculator checks only the area and minimum-dimension rules. Permit, window operation, well clearance, structure and site conditions still require project-specific review.
London permit planning
New or enlarged openings require a permit.
The City of London lists new windows and enlarging existing windows as work requiring a building permit. Foundation cutting, structural support, window-well placement and drainage are reviewed for the specific property.
- Existing interior and exterior conditions
- Final clear-opening size and window operation
- Foundation opening and structural details
- Window-well clearance and site drainage
Not sure whether your current opening qualifies?
Send an interior photo, exterior photo and rough measurements. EliteCraft can review the starting point and discuss the next steps.
See the work
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From a small basement opening to a finished egress window.
Watch an EliteCraft egress installation, then send photos of your own basement window for a project review.
Review
Interior, exterior, foundation and access.
Plan
Opening, window, well and permit details.
Install
Cut, set, seal and finish the opening.
Recent work
Clean installations and strong finished results.
Windows & doors
More than egress.
Replacement Windows
Vinyl windows measured for the opening and installed with exterior sealing and finishing.
Explore replacement windows →Entry Doors
Steel and fiberglass door systems with colour, glass and configuration options.
Explore entry doors →Patio Doors
Sliding patio door replacement with a clean, weather-tight professional finish.
Explore patio doors →Exterior Capping
Custom-bent aluminum finishing for suitable window and door exteriors.
Explore exterior capping →Customer reviews
View EliteCraft on Google ↗Trusted for communication, workmanship and cleanup.
★★★★★“Communication was smooth from start to finish, and the new windows made a huge improvement in comfort.”
Carlie H.
★★★★★“Professional, courteous and efficient throughout the project, with a thorough cleanup afterward.”
William O.
★★★★★“Quick and amazing results. The team completed twelve windows in two days.”
Chelsea L.
Ready to start?
Send photos for an egress, window or door quote.
For egress work, include one interior photo, one exterior photo and rough clear-opening measurements.