ADU Laws in Wisconsin (2026)
Wisconsin state ADU law details, key provisions, preemption status, and recent legislative changes for accessory dwelling units.
Law Name
State ADU Law
Preempts Local Ordinances
No — local rules may be stricter
Has State Law
Yes
Key Provisions
Wisconsin does not have a comprehensive statewide ADU preemption law as of 2026
ADU regulation is left to local municipalities under Wisconsin Statutes Chapter 62 (Cities) and Chapter 66 (General Municipality Law)
Milwaukee, Madison, Green Bay, and Kenosha set their own local ADU ordinances
Wisconsin Legislature has considered ADU reform but comprehensive statewide by-right ADU mandates had not been enacted as of 2026
Madison has been progressive on housing density and has allowed ADUs in residential zones through local action
Milwaukee has been exploring ADU provisions as part of its housing revitalization strategies
Legislative History
2023 — Wisconsin ADU Reform Bills (proposed, not enacted)
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.
Official Sources
Source: Wisconsin State ADU Law. Last verified April 5, 2026. View source