Egress Window Well (IRC R310.2.3)
The window well an egress window opens into, whose minimums are exactly tangent.
Example
You enter
- Well width (in) 36
- Well horizontal projection from the wall (in) 30
- Well vertical depth (in) 60
- Permanently affixed ladder or steps? no
- Does the well let the window open FULLY? yes
You get
- Area (ft²) 7.5
- Area deficit (ft²) 1.5
- Projection needed (in) 36
- Width needed (in) 43.2
- Minimums area (ft²) 9
Details, formula, and sources
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.
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).
Both provisions are short prescriptive sentences reproduced in state adoptions, building-department handouts, and window-well manufacturers' free code guides. No table is reproduced.
Estimate. AHJ and licensed professional govern.
Field names used by the API: well_width_in, well_projection_in, well_depth_in, has_ladder, opening_fully_opens, area_sf, area_deficit_sf, projection_needed_in, width_needed_in, minimums_area_sf
- Area not less than 9 sq ft of horizontal areaIRC R310.2.3
- Dimensions minimum horizontal projection AND width of 36 in - exactly tangent to the 9 sq ftIRC R310.2.3
- Full opening the well must allow the escape opening to be fully openedIRC R310.2.3
- Ladder trigger vertical depth greater than 44 inIRC R310.2.3.1
- Ladder dimensions 12 in inside width, 3 in projection, 18 in maximum vertical spacingIRC R310.2.3.1
- Encroachment the ladder may encroach into the required dimensionsIRC R310.2.3.1