How to Choose the Right Egress Window Size
Choosing the right egress window size is one of the most important steps when finishing a basement,
adding a bedroom, or renovating an older home. An improperly sized egress window can fail inspection,
delay permits, reduce home value, and--most importantly--compromise safety.
This guide explains egress window size requirements, window styles, window well dimensions, and
common mistakes so you can get it right the first time.
What Is an Egress Window?
An egress window is a code-required emergency exit window designed to allow occupants to escape and
first responders to enter during a fire or emergency. Egress windows are required in:
- Basement bedrooms
- Finished basements
- Sleeping rooms in most residential homes
Local codes may vary, but most municipalities follow International Residential Code (IRC) standards.
Minimum Egress Window Size Requirements
Most building codes require the following minimum dimensions:
-
Minimum clear opening area:
- 5.7 square feet (above grade)
- 5.0 square feet (at grade)
- Minimum opening width: 20 inches
- Minimum opening height: 24 inches
- Maximum sill height: 44 inches from the floor
Important: These measurements refer to the clear opening when the window is
fully open--not the glass size or rough opening.
Best Window Types for Egress Compliance
Not all window styles meet egress requirements, even if the window appears large.
Common egress-approved window styles include:
- In-swing casement windows (most efficient for egress)
- Sliding windows
- Single-hung in-swing windows
- Double-hung windows (often problematic)
Casement windows are often the best choice because the entire window opens, making it easier to meet
code requirements with a smaller frame.
Egress Window Well Requirements (Below-Grade Windows)
If the egress window is below ground level, a window well is required.
Typical window well code requirements include:
- Minimum area: 9 square feet
- Minimum projection from foundation: 36 inches
- Minimum width: 36 inches
- Permanent ladder or steps required if depth exceeds 44 inches
Even a correctly sized egress window can fail inspection if the window well does not meet code.
Common Egress Window Mistakes to Avoid
- Measuring the window glass instead of the clear opening
- Choosing double-hung windows that do not open wide enough
- Installing the window sill too high
- Forgetting window well clearance and ladder requirements
- Installing a casement window that conflicts with window well code
- Assuming older homes are exempt from egress rules
Note: Fixing these mistakes often requires cutting concrete again, which can
significantly increase project costs.
How to Choose the Right Egress Window Size
- Verify local building code requirements
- Select an egress-approved window style
- Confirm manufacturer clear-opening specifications
- Design the window well at the same time
- When in doubt, choose a slightly larger window
Properly sized egress windows improve:
- Fire safety
- Emergency access
- Natural light and ventilation
- Home resale value
- Legal bedroom classification
Final Thoughts: Egress Window Size Matters
Choosing the correct egress window size is not just about passing inspection--it is about protecting
lives and adding long-term value to your home. Planning ahead helps prevent costly rework and ensures
your renovation meets safety standards.
