Wisconsin Uniform Dwelling Code: Stairs & Guards

Wisconsin is one of the few states that doesn’t adopt the IRC at all. It runs its own Uniform Dwelling Code (UDC) — Wis. Admin. Code SPS 320–325 — a wholly state-authored prescriptive code for one- and two-family dwellings, mandatory statewide and administered by the DSPS. The code text is updated on a rolling basis via the Wisconsin Administrative Register, so always check the current version.

Stair, handrail and guard requirements live under SPS 321.04, using Wisconsin’s own section numbering rather than the IRC’s. One confirmed figure: under SPS 321.16, stair landings and footings must sit below the frost penetration level, or at minimum 48 in below grade — deeper than the IRC’s general footing provisions, reflecting Wisconsin’s cold-climate frost line. Beyond that footing figure, don’t assume Wisconsin’s stair or guard numbers match the IRC — go to SPS 321.04 directly rather than the US stair & guard rules, which describe the IRC baseline only.