Egress Window Well (IRC R319.4.1)
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
Checked against published worked examples from: International Code Council.
Details, formula, and sources
Scope9 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 or tablearea = 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.
Source and editionIRC R319.4.1 [R310.4.1 in IRC 2021] (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 R319.4.2 [R310.4.2 in IRC 2021] (ladder and steps).
Free accessBoth provisions are short prescriptive sentences reproduced in state adoptions, building-department handouts, and window-well manufacturers' free code guides. No table is reproduced.
What governsEstimate. AHJ and licensed professional govern.
API field nameswell_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 R319.4.1 [R310.4.1 in IRC 2021]
- Dimensions minimum horizontal projection AND width of 36 in - exactly tangent to the 9 sq ftIRC R319.4.1 [R310.4.1 in IRC 2021]
- Full opening the well must allow the escape opening to be fully openedIRC R319.4.1 [R310.4.1 in IRC 2021]
- Ladder trigger vertical depth greater than 44 inIRC R319.4.2 [R310.4.2 in IRC 2021]
- Ladder dimensions 12 in inside width, 3 in projection, 18 in maximum vertical spacingIRC R319.4.2 [R310.4.2 in IRC 2021]
- Encroachment the ladder may encroach into the required dimensionsIRC R319.4.2 [R310.4.2 in IRC 2021]