Egress windows

Where egress is requiredR310.1#

Every sleeping room requires one emergency escape and rescue opening. Basements with habitable space or containing one or more sleeping rooms also require an egress opening, even if the basement is not finished.

Minimum dimensionsR310.2.1#

The emergency escape opening must provide a minimum net clear opening of 5.7 square feet. Grade-floor openings and basement openings with direct access to an egress well may use 5.0 square feet.

Minimum clear opening height is 24 inches. Minimum clear opening width is 20 inches. Meeting both minimum dimensions does not satisfy the area requirement on its own.

Sill heightR310.2.2#

The bottom of the clear opening must be no more than 44 inches above the finished floor.

Window wellsR310.2.3#

Window wells serving basement egress openings must have a horizontal area of at least 9 square feet, with a minimum horizontal projection and width of 36 inches. The well must allow the emergency opening to fully open.

A well deeper than 44 inches requires a permanently affixed ladder or steps. The ladder or steps may encroach up to 6 inches into the required dimensions of the well.

Common inspection flags#

The most common egress window failures:

• Net clear opening calculated on rough opening instead of the actual unobstructed opening
• Casement windows where the sash hardware reduces clear width below 20 inches
• Sill height measured from the top of the rough opening instead of the finished floor
• Window well ladder missing in a well deeper than 44 inches