Green Bay Egress Windows Wisconsin's Egress Rules Are Not the IRC: What the UDC Actually Requires for a Green Bay Basement Bedroom
August 14, 2026
Green Bay Egress Windows spends a surprising amount of time un-teaching the internet. Search “egress window requirements” and nearly every result recites the International Residential Code: 5.7 square feet of net clear opening, a 44-inch maximum sill height, a 9-square-foot window well. Those numbers are real - and they are not Wisconsin’s law. One- and two-family homes here are governed by the state’s own Uniform Dwelling Code (SPS 320–325), and its egress rules in SPS 321.03(6) differ from the IRC on almost every figure that matters. If you’re planning a basement bedroom in Green Bay, De Pere, Howard, Suamico, or Bellevue, the UDC is the code your municipal inspector carries. Here’s what it actually says.
First: why Wisconsin is different at all
Most states adopt the IRC (with amendments) as their residential building code. Wisconsin never did. The state wrote its own Uniform Dwelling Code, in force since June 1, 1980, and it applies statewide to one- and two-family dwellings - administered not by the state directly but by municipal inspection offices. In our service area that means the City of Green Bay’s Building Inspection division, De Pere’s Building Inspection Division, Howard’s Code Administration department, Suamico’s Building Inspection/Zoning office, and Bellevue’s Community Development department each review plans, issue permits, and inspect against the UDC.
The practical consequence: national how-to content, IRC-spec “egress kits,” and advice from contractors who work across the state line in IRC territory can all be confidently wrong about your basement. Sometimes they’d make you overbuild. Occasionally - and this is worse - they’d let a detail pass that Wisconsin actually regulates.
What triggers the requirement
Start with when you need an egress window at all. Under SPS 321.03(5)(b), a basement used for sleeping needs a second exit, and the standard way to provide it is an egress window complying with SPS 321.03(6) located in each bedroom. Each is the operative word: finish two basement bedrooms and each sleeping room needs its own compliant opening. A rec room, office, or gym doesn’t trigger the rule - but the moment a room is used or listed as a bedroom, it does, and appraisers and home inspectors apply exactly that logic.
The window itself: 20 by 24, either way up
The heart of the Wisconsin standard is SPS 321.03(6)(b)1:
“The nominal size of the net clear window opening shall be at least 20 inches by 24 inches irrespective of height or width.”
Read that twice, because it’s doing two unusual things. First, there is no square-footage requirement - no 5.7, no 5.0. The minimum is dimensional: the clear opening must be at least 20 inches in one direction and 24 in the other. Second, “irrespective of height or width” means the orientation is your choice: 20 wide by 24 tall complies, and so does 24 wide by 20 tall. That’s roughly 3.3 square feet - dramatically smaller than the IRC’s 5.7 - which means windows that would flunk an inspection in Minnesota or Michigan can be fully legal here.
Two companion rules keep the measurement honest. SPS 321.03(6)(b)2 says no portion of the window - “stops, stools, meeting rails and operator arms” - may infringe on the required opening: you measure the hole a person actually climbs through, not the sash size on the order sheet. And SPS 321.03(6)(a) requires the window be openable from the inside without the use of tools or the removal of a sash; storm windows and screens must open from inside too. A compliant window painted shut, or covered by a screwed-on storm, is a non-compliant exit.
The sill: 60 inches, with a platform rule the IRC doesn’t have
The IRC caps sill height at 44 inches. Wisconsin allows 60 inches - but with a mechanism all its own in SPS 321.03(6)(d): if the lowest point of the clear opening sits more than 46 inches above the floor, you must install a permanent platform below it - a flat surface at least 20 inches wide and 9 inches deep, positioned no more than 46 inches directly below the opening, with its top no more than 24 inches above the floor, built to support a 200-pound live load.
This is a genuinely homeowner-friendly difference. Green Bay’s older housing - the pre-war east and west sides, the Astor neighborhood, the block ranches that ring the city - is full of basements where dropping a sill to 44 inches would mean deeper cuts, deeper wells, and more money. The UDC’s higher sill allowance plus a built-in step can make a compliant opening out of a wall the IRC would send back to the saw. It’s also a trap in reverse: that loose step stool under the window doesn’t count. The platform must be permanent.
The window well: width rules, not area rules
Below grade, the UDC regulates the areaway - its word for the window well - in SPS 321.03(6)(e), and again the logic differs from the IRC’s 9-square-foot minimum:
- Width: the areaway must be at least as wide as the window it serves. (A national kit well narrower than your window fails here regardless of its total area.)
- Projection: at least 36 inches, measured perpendicular from the below-grade wall.
- Ladder: required when the bottom of the areaway is more than 46 inches below adjacent grade or the top of the enclosure - and given Green Bay sill depths and our 48-inch-class frost footings, most egress wells here cross that line. Rungs must have at least 12 inches of inside width, project at least 3 inches from the wall behind them, rise no more than 12 inches between rungs, extend to within 12 inches of grade, and carry a 200-pound concentrated load. The ladder may infringe on the required well area by at most 6 inches.
- Water: the areaway “shall be constructed such that water entering the areaway does not enter the dwelling.” In Brown County clay, that sentence is the whole drainage specification - gravel bed, footing-tile tie-in or dry well, graded backfill. It’s also why well construction is where cheap installs fail.
Side-by-side, for the skimmers
| Requirement | Wisconsin UDC | IRC R310 |
|---|---|---|
| Net clear opening | ≥ 20” × 24”, either orientation (~3.3 sq ft) | ≥ 5.7 sq ft; ≥24” high, ≥20” wide |
| Max sill height | 60” (permanent platform required above 46”) | 44” |
| Well size | Width ≥ window width; ≥36” projection | ≥9 sq ft; ≥36” × 36” |
| Ladder trigger | Well bottom >46” deep | Well >44” deep |
What this means for your project
Don’t spec from national content. A Green Bay basement bedroom lives or dies by SPS 321.03, and your municipal inspector reviews against it - each of the five communities we serve runs its own office, which is why the permit filing is part of every install we do.
Don’t assume smaller-is-cheaper means smaller-is-better. The 20-by-24 minimum is a legal floor. Most homeowners still choose larger casements or sliders for light, easier exit, and resale optics in a market where buyers have seen IRC-sized openings. We quote both.
Older homes get a judgment call. The UDC applies to homes built since mid-1980; on Green Bay’s substantial pre-1980 stock, the municipal office decides how standards apply to remodel work - in practice, new openings get built to current UDC specs, because that’s what the inspector signs.
Nobody guarantees an inspection. We build to the text quoted above and handle the permit end to end, but the sign-off belongs to your city or village. Treat any contractor’s “guaranteed to pass” as the warning it is.
If you’re planning a basement bedroom - or fixing one an inspector just flagged - the code compliance upgrades page shows how we scope against this checklist, the pricing page publishes every number, and the form gets you a free on-site measure with the UDC math done on your actual wall.