The International Residential Code (IRC) is a comprehensive residential code that creates minimum regulations for one- and two-family dwellings of three stories or less. It currently requires all finished basements and basement bedrooms have a minimum of two exits. The first is normal basement steps to the first floor, and the second is an emergency-egress window or door to the outside of the dwelling.
- Minimum width of clear opening: 20 inches*
- Minimum height of clear opening: 24 inches*
- Minimum net clear opening: 5.7 sq. ft. or 5.0 sq. ft. for ground floor windows
- Maximum sill height above floor: 44 inches
Note that 20 in. x 24 in. does not provide a net clear opening of 5.7 sq. ft. A 20 in. wide opening would require a height of 42 in. A 24 in. high opening, would require a width of 35 in.
Window Well Requirements
Egress Window Wells are required when the window is below ground elevation. The wells must have a minimum horizontal projection of 36 inches and a vertical width of 36 in. (9 sq. ft. of surface area required). These must include ladders on window wells deeper than 44″. The ladders can’t encroach on the well more than 6″ and each rung must be 12″ wide, 3″ from the well wall, and cannot be more than 18″ apart. The well cover must be removable without the use of special tools.
Types of Egress Windows
Double Hung Window–slide vertically, but require large sizes to meet IRC guidelines.
Casement Out-swing Window: Pro’s – Many inexpensive Windows are available; Con’s – Usually not made with egress hinges, many don’t open 90 degrees, requires the use of wider widows and wells, could interfere with well covers if the window is partially above top of the well, limited or no warranty
Egress 48” Sliding Basement Window: Pro’s – 8” to 12” jamb depths, meets IRC 20” clear opening requirement, meets Energy Star requirements, 10 year warranty; Con’s – more expensive
Single Hung In-swing Window: with egress hinges this window provides traditional operation of the window while also allowing for in-swing, meaning the window can be smaller and still meet IRC requirements.
Casement In-swing Window: Pro’s – uses egress hinges to meet 5.7 sq. ft. IRC requirement, but can only be opened inward.