Accessory Dwelling Units (ADUs) are an affordable type of infill housing. They are small, include a bedroom, kitchen and bathroom, and can be either attached or detached from the main house on the property.


Recently in Olympia, Washington, there has been energy put into creating more assistance from the City level for homeowners who want to and build an ADU on their property. This is being brought on by a small ad hoc group made up of community members and students and members of the City Planning Department.

This group, sometimes referring to themselves as the Accessory Dwelling Program Committee, is dedicated to facilitating the creation of an ADU program in Olympia similar to the program that was set up in Santa Cruz in 2003. This program will include:
  • A manual available through the City planing department that will help guide homeowners step-by-step through the entire process of building an ADU. 
  •  A menu of prototype designs (pre-approved by City) that will and help them begin forming ideas for what they want their ADU to be like allowing homeowners save time and money during the design process. 
  • More promotion of ADUs and increasing awareness of ADUs as a viable and affordable housing option.

Quick Facts About ADUs in Olympia:
  • ADUs are permitted in all residential districts.
  • The ADU shall have a gross floor area of no more than eight hundred (800) square feet, and no more than the following equivalent ratios:
    • forty percent (40%) of the gross floor area of the primary residence and accessory dwelling unit combined, or 
    • sixty-six and two-thirds percent (66 2/3%) of the gross floor area of the primary residence alone; excluding any garage area, except as authorized by Section 18.04.060(A)(7).
  • The property owner must live on the site as his/her principal residence (in either the main house or the ADU) 
This blog was created as an online resource for information on ADUs and other uses of small home design by Cameron Hostetter for an independent learning contract at the Evergreen State College in Olympia, WA.