Accessory Structures in Madison, WI (2026)
9 verified accessory structures rules for Madison, Wisconsin, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Madison legalized accessory dwelling units citywide in 2013 under MGO 28.151. ADUs are allowed in all residential districts subject to size, owner-occupancy, and parking standards. One of the first Midwestern cities to embrace ADUs.
Accessory Structures: Adu Rules
Few RestrictionsADU Permits
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 ADU Permits
Few RestrictionsADU Impact Fees
Madison does not charge development impact fees on residential ADUs. Wisconsin Statute 66.0617 authorizes municipal impact fees broadly but requires a fee study demonstrating new capacity need. Madison currently imposes only standard building permit fees through the Building Inspection Division. Madison Water Utility charges connection fees only if a new service line is installed.
Madison ADU Impact Fees
Few RestrictionsADU Owner Occupancy
Madison does not require owner-occupancy for ADU properties under MGO Chapter 28. Property owners may build an ADU and rent both units to separate tenants. The Common Council removed the owner-occupancy requirement in 2020 amendments to Section 28.151. Wisconsin has no state preemption on owner-occupancy. Condominium and HOA covenants under Wisconsin Statute Chapter 703 may impose private restrictions.
Madison ADU Owner Occupancy
Few RestrictionsADU Rental Restrictions
Madison allows long-term rental of legal ADUs without special licensing. Short-term rentals (under 30 days) require a Tourist Rooming House license under MGO Chapter 9 and Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) ATCP 72 license. Wisconsin Act 59 (2017) preempts outright STR bans but allows reasonable regulation. Madison's STR ordinance limits non-owner-occupied STRs.
Madison ADU Rental Restrictions
Some RestrictionsShed Rules
Madison requires a zoning permit for sheds over 150 square feet and a building permit for structures over 200 square feet. Setbacks are typically 3 feet from side and rear lot lines per MGO 28.
Accessory Structures: Shed Rules
Some RestrictionsGarage Conversions
Garage conversions to habitable space require a building permit in Madison and must meet WI Uniform Dwelling Code for egress, insulation, and ventilation. Converting to an ADU follows MGO 28.151 with parking replacement if required.
Accessory Structures: Garage Conversions
Some RestrictionsCarport Rules
Madison treats carports as accessory structures under MGO 28 zoning. Permits are required and setbacks and coverage limits match detached garage rules. Cloth or canopy carports are generally prohibited as permanent structures.
Accessory Structures: Carport Rules
Some RestrictionsTiny Homes
Tiny homes on foundations are allowed in Madison if they meet WI Uniform Dwelling Code and zoning minimum dwelling size. Tiny houses on wheels are treated as RVs and not allowed for permanent residence outside RV parks.
Accessory Structures: Tiny Homes
Some Restrictions2017 Wis. Act 67 (county and municipal conditional use permits)
Conditional use permits. (a) In this subsection: 1. “Conditional use” means a use allowed under a conditional use permit, special exception, or other special zoning permission issued by a county, but does not include a variance. 2. “Substantial evidence” means facts and information, other than merely personal preferences or speculation, directly pertaining to the requirements and conditions an ...
Looking for Dane County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Madison city rules.
Accessory Structures in Dane County →