Egress Window
An egress window provides an emergency escape and rescue opening from a home. Egress requirements are especially important in sleeping rooms and basements.
What Makes a Window an Egress Window?
The key measurement is the net clear opening the actual unobstructed space available when the window is fully open. Overall window size alone does not determine whether it qualifies.
Common Residential Measurements
Minimum clear opening width: 20 inches.
Minimum clear opening height: 24 inches.
Minimum net clear opening: generally 5.7 square feet.
Maximum sill height: generally 44 inches above the finished floor.
Meeting the minimum width and minimum height alone does not create a 5.7-square-foot opening. The required clear-opening area must also be satisfied. Code requirements and exceptions should always be verified for the specific project and jurisdiction.
Why Does Window Style Matter?
Two windows with the same overall dimensions can provide very different clear openings. A double-hung window retains one sash in the opening, while a casement may provide a larger clear opening from a smaller overall unit.
Can Replacement Change Egress?
Yes. A replacement installed inside an existing frame can reduce the usable clear opening because the new frame occupies some of the opening. Egress should be considered before changing a window that serves as an emergency escape and rescue opening.
Basement Windows and Wells
Below-grade egress windows may also need a properly sized window well so the window can fully open and a person can escape. Deeper wells may require permanently installed steps or a ladder.
Related Window Terms
Casement Window • Double-Hung Window • Pocket Replacement • Full-Frame Replacement • Window Sill • Rough Opening • Tempered Glass