Madison is one of the Midwest's most ADU-friendly cities. Madison General Ordinances (MGO) Chapter 28 (Zoning Code) permits accessory dwelling units (ADUs) by-right in most residential districts (TR-C1, TR-C2, TR-C3, TR-C4, TR-V1, TR-V2, TR-U1, TR-U2, SR-C1, SR-C2, SR-V1, SR-V2) following the 2013 zoning code rewrite. Permits are filed with the City of Madison Building Inspection Division through the Accela permit portal. Wisconsin Uniform Dwelling Code (SPS 320-325) applies.
Madison General Ordinances Chapter 28 (Zoning Code) Section 28.151 establishes accessory dwelling units as a permitted accessory use in all Traditional Residential (TR) and Suburban Residential (SR) districts. ADUs may be attached, detached, or located above a detached garage. Standards: ADU floor area limited to 800 square feet or 75 percent of the principal dwelling floor area, whichever is less; ADU must use the same address with a unit designation; one off-street parking space required for the ADU; maximum height of 25 feet for detached ADUs; setbacks follow accessory structure standards (typically 3 feet side/rear) under Section 28.135. Building permits issue through Madison Building Inspection Division using the Accela Citizen Access portal (accela.cityofmadison.com). Required: zoning verification, building permit, electrical permit (Wisconsin DSPS oversight under Wis. Stat. 101.862), plumbing permit (licensed master plumber under Wis. Stat. 145), HVAC permit. Wisconsin Uniform Dwelling Code SPS 320-325 sets minimum residential standards. Cold-climate construction requires frost-protected foundations to 48-inch frost depth. Historic district review through the Madison Landmarks Commission applies in Mansion Hill, Third Lake Ridge, University Heights, Marquette Bungalows, and other designated districts.
Unpermitted ADU construction violates MGO Chapter 28 and triggers stop-work orders under MGO 28.183, with daily forfeitures of $100 to $1,000 per offense. Wisconsin DSPS may impose separate penalties for unlicensed plumbing or electrical work under Wis. Stat. 145 and 101.862. Building Inspection may issue raze orders for unsafe structures. Liens may be filed for unpaid fines and corrective work costs.
Madison, WI
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See how Madison's adu permits rules stack up against other locations.
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