Accessory Dwelling Units

The Washington State Department of Commerce is seeking your input on Accessory Dwelling Units (ADU).

New amendments to RCW 36.70A.070 require local governments, in their housing element updates, to consider the role of ADUs in meeting housing needs. Many bills about ADUs have also been presented in the last few years. As a result, Commerce set aside funding to update our ADU guidance which was first developed in 1994, and is still referenced in statute (RCW 43.63A.215).

The guidance update will include:

  • Recommendations for cities may include considerations related to parking, size, and design, and use as short-term rentals, affordability incentives or other tools to encourage the development and affordability of ADUs.
  • A recommended approach for counties may include considerations in rural and resource lands, design, use for family, farm help, and short-term rentals, and suggestions in Limited Areas of More Intense Rural Development (LAMIRDS) and unincorporated urban growth areas.
  • A sample presentation and editable handouts for local government staff to use as they work on local Accessory Dwelling Unit ordinances.
  • Two recorded webinars to train local government staff planners on the ADU recommended policies: one for cities and one for counties.

Draft guidance is expected in late 2022. If you have specific recent experience in developing ADU regulations and would like to get involved to share your knowledge, please contact Anne Fritzel at or Catherine McCoy at

More information will be added to the Growth Management Planning for Housing webpage and the Housing EZView website as it becomes available.