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Clearing the Path for More Backyard Cottages in Seattle

Mayor Jenny A. Durkan today heralded the Hearing Examiner ruling on the Final Environmental Impact Statement that clears the path for more accessory dwelling units (ADUs), or backyard cottages, across Seattle.

“Seattle faces an affordability and housing crisis, and we are acting to increase the supply of housing options as quickly as possible. We need to use every tool in our toolbox to boost the supply of housing – and that includes knocking down barriers for homeowners to build more backyard cottages and in-law units. We must address the significant financial barriers and lengthy, complicated permitting process for backyard cottages in Seattle,” said Mayor Durkan. “Now, we will continue listening to community on how we can best move forward and giving homeowners – not developers – more flexibility and renters more choices.”

In her ruling, Seattle Deputy Hearing Examiner Barbara Dykes Ehrlichman found that the City’s environmental analysis, or Environmental Impact Statement, of several additional policy options to encourage ADUs adequately explores the potential outcomes. The ruling clears the way for legislative action on a proposed ordinance.

To streamline the City permitting process for ADUs, Mayor Durkan has directed City departments to offer pre-approved backyard cottage designs to save owners time and money. As Council discusses and adopts new ADU standards this summer, the Seattle Department of Construction and Inspections will issue a call for submissions of cottage plans for pre-approval. A jury of volunteer members of the Seattle Design Commission, Planning Commission, Design Review Boards, and Construction Code Advisory Board will recommend plans to be reviewed and pre-approved by SDCI. Pre-approved cottage plans will be available to the public by the end of the year.

ADUs inside the home have been allowed in Seattle since 1994. Backyard cottages were first piloted in 2006 and allowed citywide in 2010. They provide the only new housing options other than a detached house in Seattle’s single-family zones.

The City’s environmental analysis found that with these policy options, we can expect about twice as many ADUs constructed over 10 years – up to 4,400 from less than 2,000 under current rules. The analysis also found the number of existing detached houses demolished to make way for larger homes would decline by 22 percent.

The Office of Planning and Community Development is asking the public to submit comments on ADUs by emailing The City Council public hearing on its ADU proposal, another opportunity for public comment, is scheduled for June 11 at City Hall.