Egress Window Well (IRC R310.2.3)
The window well egress-window-check names and skips, and it has the same shape as its sibling: minimums that are exactly tangent. 9 sq ft of horizontal area with a minimum projection AND width of 36 in -- and 36 x 36 is precisely 9 sq ft, so the smallest compliant well is square and anything narrower fails on the dimension no matter how far it projects. Reports the partner dimension either way. Two more conditions: the well must let the escape opening open FULLY, which an outward-swinging sash can defeat in a shallow projection while every measurement still reads compliant, and a well over 44 in deep needs a permanently affixed ladder -- 12 in inside width, 3 in projection, 18 in maximum rung spacing, and the code lets it encroach into the required dimensions, so it is not a reason to build the well bigger.
Formula and source
area = width x projection / 144; pass requires area >= 9 sq ft AND width >= 36 in AND projection >= 36 in AND the opening able to open fully; projection needed = max(36, 1296 / width); width needed = max(36, 1296 / projection); a ladder is required where the vertical depth exceeds 44 in, with rungs of not less than 12 in inside width, not less than 3 in projection, and not more than 18 in vertical spacing.
IRC R310.2.3 (window wells - minimum horizontal area of 9 sq ft, minimum horizontal projection and width of 36 in, and an area allowing the emergency escape and rescue opening to be fully opened) and R310.2.3.1 (ladder and steps).
Audience
This tile is built for carpentry and the adjacent professions in the Carpentry and Construction group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.