Encouraging Backyard Cottages

What's Happening Now

We are working with the City Council on an Environmental Impact Statement (EIS) to study the potential effects of removing barriers to creating accessory dwelling units (ADUs) in single-family zones. ADUs include backyard cottages, known as detached accessory dwelling units (DADUs), and in-law apartments, known as attached accessory dwelling units (AADUs). Currently, we're in the scoping phase of the EIS, and we want your input on what to consider and analyze as we explore allowing more ADUs in Seattle's neighborhoods. Visit the ADU EIS website to learn more.

Since 2010, the City has allowed backyard cottages in all single-family residential neighborhoods. To encourage more of this housing type, in 2014 the City Council adopted Resolution 31547 directing us to explore changes that could make them easier to build and allow them on more lots in Seattle. Last year, Councilmember Mike O'Brien released a draft proposal for removing barriers to backyard cottages and in-law apartments. After reviewing an appeal of the environmental review, in December 2016 the Hearing Examiner reversed the Determination of Non-Significance (DNS) and directed us to prepare an EIS. Before Councilmember O'Brien released his proposal, we co-hosted two public meetings in January and February 2016. During our outreach, we received hundreds of comments about how we can make it easier for people to create ADUs.

Project Benefits

Encouraging backyard cottages can increase the supply and variety of housing options in single-family neighborhoods. Backyard cottages share many characteristics with small single-family houses: a single unit with no shared walls in quiet residential neighborhoods. Due to their smaller size and lack of additional land cost, backyard cottages can offer a more affordable housing option in neighborhoods where homes are unaffordable for many people.

Backyard cottages also offer a good housing option for various household types, including families with children and multi-generational households. Families can respond to changing needs for living space by adding a backyard cottage or an in-law apartment. Property owners can also rent their ADU to earn additional income that makes it easier for them to remain in their neighborhood.

End Result

Once code barriers are removed, it will be easier for property owners to get permit and construct ADUs, broadening the mix of housing options available in single-family areas.

Environmental Impact Statement

In partnership with the City Council, we are beginning the environmental review process to study the effects of removing barriers to creating ADUs.

Community Meetings

In January and February 2016, we co-hosted two community meetings with Councilmember Mike O'Brien to discuss policy options that could remove barriers to creating backyard cottages and ADUs. Thank you to everyone who attended and shared your ideas and feedback. On the Project Documents page, you can read a summary of what we heard and review our meeting materials.

Sign up for email updates on the progress of our work and additional opportunities for public comment.

Tell Us Your Story

We're interested in hearing about the experiences of those who have built, considered building, or lived near a backyard cottage or ADU. Please contact Nick Welch at nicolas.welch@seattle.gov to tell us your story.

SEPA Draft Legislation

In May 2016, Councilmember Mike O'Brien published draft legislation for environmental review under the State Environmental Policy Act (SEPA), along with the following materials:

Following an appeal of the environmental review, the Hearing Examiner issued a decision directing us to prepare an Environmental Impact Statement (EIS). 

Community Meetings

City Council Lunch and Learn

Reports