Below are some of the highlights of the 2006 IRC (International Residential Code), Section R310, as it pertains to windows below ground level.
Sill height of window above floor: Not to exceed 44 inches. Minimum opening area: = 5.7 sq. ft. Minimum opening height: ≥ 24" Minimum opening width: ≥ 20"
WINDOW WELLS/AREA WELLS
Required where window opening sill height is below ground elevation. Horizontal dimensions: ≥ 9 sq. ft. Horizontal projection: ≥ 36"
Required on window wells deeper than 44" and must be permanently attached. Ladder may encroach into well up to 6". Step distance between rungs: ≤ 18". Rungs: 12" wide or greater and must project a minimum of 3" away from wall but maximum of 6".
GRATES AND COVERS
Shall be removable without special tools.
Code sponsored by: The International Code Coucil, the Building Officials Code Administration (BOCA), the Uniform Building Codes (UBC), and the Southern Building Code Congress International (SBCCI).