ADU Rules in Wisconsin (2026)
ADU rules in Wisconsin — no statewide ADU law. Regulation is entirely local. Key provisions and city-specific frameworks for accessory dwelling units.
Law Name
Preempts Local Ordinances
No — local rules may be stricter
Has State Law
No — regulation is local
Statewide Preemption Status Unconfirmed
No statewide preemption statute was confirmed for this jurisdiction — regulation is local. Local governments retain full authority to set their own rules.
Local Control Framework
Wisconsin does not have a comprehensive statewide ADU preemption law as of 2026 · Source
ADU regulation is left to local municipalities under Wisconsin Statutes Chapter 62 (Cities) and Chapter 66 (General Municipality Law) · Source
Milwaukee, Madison, Green Bay, and Kenosha set their own local ADU ordinances · Source
Wisconsin Legislature has considered ADU reform but comprehensive statewide by-right ADU mandates had not been enacted as of 2026 · Source
Madison has been progressive on housing density and has allowed ADUs in residential zones through local action · Source
Milwaukee has been exploring ADU provisions as part of its housing revitalization strategies · Source
Legislative History
2023 — Wisconsin ADU Reform Bills (proposed, not enacted) · Source
Wisconsin Legislature considered bills to allow ADUs by right statewide but comprehensive ADU preemption had not been enacted as of 2026. Local municipalities retain full authority over ADU regulations under Wisconsin's zoning enabling statutes. · Source
Source: Wisconsin Local Zoning Authority. Last verified April 5, 2026. View source