Milwaukee treats an accessory dwelling unit (ADU) as a smaller unit on the same lot as a one- or two-family home. The City’s ADU guidance says the use is a limited use in a number of residential, residential-office, business, shopping, commercial-service, and industrial districts. Check the exact zone in the City’s property map and the current zoning code.
Match the ADU form to the principal residence
Milwaukee’s screening rules differ by form:
- Internal and attached ADUs are allowed only within or attached to a single-family residence.
- A detached ADU is allowed only where the property has a single-family or two-family residence.
- No more than one ADU may be located on a property, and the ADU must be smaller than the principal residence.
- At permit submission, an owner must occupy the existing principal residence as their primary residence. The ordinance quotation on the City page describes an exception when the ADU and a new principal dwelling are constructed at the same time.
The allowed limited-use districts listed by the City are RS1–RS6, RT1–RT4, RM1–RM7, RO1–RO2, LB1–LB3, RB1–RB2, NS1–NS2, CS, and IM. A district match alone does not answer the form and dwelling conditions.
Check overlays, historic review, and services
The City says a parcel overlay may add rules, and exterior work in a historic district can require Historic Preservation Committee review. Milwaukee’s guidance also states that a detached ADU needs a direct sewer and water-main connection separate from the principal home’s sewer-main connection. Confirm the applicable utility route, current code, zone, and historic status with the City; this article is a screen, not a permit determination.