What Is an ADU?
An ADU is a second, self-contained home on your lot with its own entrance, kitchen and bath.
A Second Home on Your Property
An ADU — Accessory Dwelling Unit — is a fully self-contained living space that exists on the same lot as a primary residence. It has its own entrance, kitchen, bathroom, and sleeping area. It functions as a complete home. If you already know the definition and want the Madison sequence, see how to build an ADU in Madison.
ADUs are also called: Accessory Dwelling Units, Tiny Homes, In-Law Suites, Granny Flats, Backyard Cottages, Coach Houses, Secondary Suites. The terminology varies — the concept is the same.
Under Wisconsin and local zoning law, an ADU is a permitted land use on most single-family residential lots in Dane County — subject to size limits, setbacks, and municipality-specific requirements that we navigate for you.
Four Types. One Specialist.
The Case for Adding an ADU
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