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ADU Focus Group

Accessory Dwelling Unit (ADU) Policy

Thurston County is developing standards to allow accessory dwelling units (ADUs) in the rural, unincorporated areas of Thurston County.

What is an ADU?

An accessory dwelling unit (ADU) is a small, separate living unit on the same lot as a single-family home. An ADU has all the basic facilities for day-to-day living independent of the main home, such as a kitchen, sleeping area, and a bathroom.

As the term "accessory" implies, ADUs are generally smaller in size than the main residence on the lot. ADUs are sometimes called "mother-in-law apartments" or "granny flats" because they are often used to house extended family. Typically, an ADU can be attached to the main home, detached, or an internal conversion, such as of a basement.

The County is currently exploring the types of ADUs that will best meet both state law and the needs of Thurston County residents.

Types of ADU
Image by City of St. Paul

Contact Us

Interested Parties: If you would like to be added to our Web Mail list, please click here.

Staff Contact: Krosbie Carter, Thurston County Associate Planner. Phone: (360) 786-5505 Email: carterk@co.thurston.wa.us


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