Below are some of the highlights of the 2006 IRC (International Residential Code), Section R310, as it pertains to windows below ground level.

WINDOWS

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"

LADDERS

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).