Green Bay, WI Accessory Structures: ADU Rules (2026)

Green Bay's zoning power is granted by Wis. Stat. Sec. 62.23 and exercised through Chapter 44 of the Code of Ordinances. The definitions division (Chapter 44, Article III, Division 2) defines an Accessory Dwelling Unit as a residential dwelling unit on the same parcel as a single-family, two-family duplex, or two-family semi-detached dwelling that provides complete independent living facilities for one family, consistent with the Wisconsin Uniform Dwelling Code (administered by Wisconsin DSPS under Wis. Admin. Code Chapters SPS 320-325). Article VI of Chapter 44 governs Residential Districts. Under the December 2025 zoning code update reported by Wisconsin Public Radio, accessory dwelling units are allowed in all residential districts subject to issuance of a Conditional Use Permit, rather than as a permitted use by right. The same package of amendments allowed duplexes in single-family zones and three- to four-unit buildings with conditional permits, reduced certain lot size minimums, and adjusted height standards in higher-density districts. Once a CUP is granted, the ADU does not count as an additional accessory structure on the property, so an owner can still have a typical detached accessory building (garage, shed) in addition to the ADU. Building permits for the ADU itself are issued through the city Inspection Division, and the structure must meet the Wisconsin Uniform Dwelling Code (one- and two-family) or Wisconsin Commercial Building Code as applicable. Specific dimensional standards (size cap, setbacks, height, parking) are set by the current text of Chapter 44, Articles VI and VII, and by the conditions imposed in the CUP.