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Thurston County facilities are open to the public with safety measures to slow the spread of COVID-19 and protect public and employee health. Learn more here.

Accessory Dwelling Unit (ADU) Ordinance

On December 15, 2020 the Board of County Commissioners adopted Ordinance 15952 to allow Accessory Dwelling Units (ADUs) in rural, unincorporated areas of Thurston County when all regulations and standards pertaining to ADUs can be met.  ADUs are also allowed in the Urban Growth Areas of Olympia, Lacey, Tumwater, and Grand Mound.  Click on the following links to view the ordinances. 

What is an ADU
An ADU is a small, separate, home built on the same lot as a single-family home.  ADUs can be an addition to a single-family home, a conversion of a basement, an attached or detached garage or outbuilding, or a new detached structure. An ADU includes a kitchen, bedroom(s), and bathroom. ADUs are smaller in size than the main home on the lot.

Permitting Information
Conduct the research before making application for an ADU.  The following links will assist with your research potentially saving you time and money.

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