Encouraging Backyard Cottages

What's Happening Now

The City is proposing to remove regulatory barriers and make it easier for property owners to create accessory dwelling units (ADUs) and increase the number of variety of housing choices in Seattle's 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).

On May 10, 2018, the City issued a Draft Environmental Impact Statement (EIS) that analyzes three alternatives for Land Use Code changes and identifies the potential environmental impacts of each alternative. The Draft EIS comment period closed on June 25, 2018. We are now preparing the Final EIS, which we will include responses to all substantive comments received on the Draft EIS. Visit the ADU EIS website to learn more or make a comment on the Draft EIS.

Since 2010, the City has allowed backyard cottages in all single-family zones. 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 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.

Accessory dwelling units 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

Removing regulatory barriers will help property owners permit and construct ADUs, broadening the mix of housing options available in single-family zones.

Environmental Impact Statement

In partnership with the City Council, we are completing the environmental review process to study the effects of removing barriers to creating ADUs. On May 10, 2018, we issued a Draft Environmental Impact Statement. Visit the ADU EIS website to learn more. 

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.

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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.

Draft Environmental Impact Statement

On May 10, 2018, the City issued a Draft EIS analyzing three alternatives for Land Use Code changes related to ADUs. Visit the ADU EIS website to learn more, review the analysis, and make a comment on the Draft EIS.

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