Egress Window

An egress window is a window that meets minimum size requirements established by the International Residential Code (IRC) to allow occupants to escape (and rescuers to enter) in an emergency such as a fire. The IRC mandates egress windows in every sleeping room and in every finished basement used as a sleeping area.

Egress Window Code Requirements (IRC R310)

To qualify as an egress window, the opening must meet ALL of the following minimums when the window is fully open:

• Minimum opening height: 24 inches
• Minimum opening width: 20 inches
• Minimum net clear opening area: 5.7 square feet (5.0 sq ft for ground floor)
• Maximum sill height: 44 inches above the finished floor

Note: these are the opening dimensions when the window is fully open — not the overall window size. A window that is large enough when closed may still fail egress if the opening mechanism doesn’t provide the required clear opening.

Window Types and Egress Compliance

• Double-hung — only the lower sash opens; must be large enough that the lower sash alone meets the opening requirement
• Casement — opens to nearly 90°; generally easiest to make egress-compliant
• Sliding — only half the window width opens; the half that opens must meet the requirements
• Awning/hopper — rarely meet egress requirements due to limited opening height or restricted angle

Basement Egress Windows

Installing an egress window in a basement wall typically requires cutting through the foundation, excavating a window well, and installing the window well drain system. This is a significant construction project costing $3,000–$6,000 in the Columbus area, but it is required to legally use a basement room as a sleeping area.