Plan Commission approves accessory dwelling unit zoning rules, including owner-occupancy verification at permit stage

The Milwaukee City Plan Commission voted unanimously April 7 to recommend approval of zoning-code provisions to permit accessory dwelling units (ADUs) across the city (file 240,999). The ordinance defines ADUs, sets size and siting standards, and requires at least one owner of the principal dwelling to occupy the principal unit at the time an ADU building permit is submitted.

Department of City Development staff said ADUs historically existed across Milwaukee and that many other U.S. cities have recently legalized them. Staff outlined three ADU forms covered by the amendment: internal (for example a basement or attic conversion), attached additions and detached secondary structures (such as a cottage or a unit above a garage). The proposed ordinance establishes minimum and maximum unit sizes (minimum 300 square feet; maximum 1,000 square feet for internal/attached ADUs; maximum 1,300 square feet for detached ADUs), maintains standard setback and height relationships, and imposes no additional off-street parking requirement.

To address stakeholder concerns about speculative conversions and absentee landlords, the ordinance requires proof of owner occupancy at the time of filing for the ADU permit. Acceptable verification methods listed in the hearing included motor-vehicle registration, state ID, voter registration, a federal or state income-tax return or utility bill. The measure also prohibits exterior fire egress on the primary facade above the second floor to reduce front-stair installations that have raised neighborhood objections.

Sponsors, including Common Council President Michael Perez and Alderman Ormond Baumann, urged the commission to approve the measure as a tool to expand housing options and support intergenerational living. Staff and several councilmembers noted that jurisdictions with ADU rules generally see gradual, scattered uptake — not an immediate wave of new units — which allows the city to adjust regulations if needed.

Commissioner Willie Smith moved to approve file 240,999; Commissioner Jesus Gonzales seconded. The motion passed on a roll-call vote, all five commissioners voting aye.

Following the commission’s approval, sponsors and staff said they will continue to monitor implementation and explore complementary programs, such as outreach and potential incentives, to encourage equitable uptake by small and emerging local developers and homeowners.