ADU Permits: Madison vs Sun Prairie
How do adu permits rules compare between Madison, WI and Sun Prairie, WI?
Madison, WI
Dane County
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.
View full Madison rules →Sun Prairie, WI
Dane County
No data available yet for Sun Prairie.
Key Facts Comparison
| Fact | Madison | Sun Prairie |
|---|---|---|
| Code Authority | MGO 28.151 | - |
| By-Right Districts | All TR and SR zones | - |
| Max Size | 800 sq ft or 75% of primary | - |
| Max Height | 25 feet detached | - |
| Filing Portal | Accela Citizen Access | - |
| State Code | Wisconsin SPS 320-325 | - |
Highlighted rows indicate differences between cities.
Madison FAQ
Are ADUs allowed in Madison single-family neighborhoods?
Yes. Madison's 2013 zoning code rewrite permits ADUs by-right in all Traditional Residential (TR) and Suburban Residential (SR) districts under MGO 28.151. This includes most single-family neighborhoods such as Atwood, Schenk-Atwood, Tenney-Lapham, Sherman, and the near-east and near-west sides.
How big can my Madison ADU be?
MGO 28.151 limits ADUs to 800 square feet or 75 percent of the principal dwelling floor area, whichever is less. Detached ADUs are capped at 25 feet height. One off-street parking space is required. Wisconsin Uniform Dwelling Code SPS 320-325 sets minimum residential construction standards.
Sun Prairie FAQ
No FAQs available.
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