Encouraging Backyard Cottages

A backyard cottage (detached accessory dwelling unit) above a garage.
Removing barriers to permitting and constructing backyard cottages (detached accessory dwelling units).

What's Happening Now

Available on Councilmember Mike O’Brien’s website is a draft of legislation that would remove barriers to the creation of backyard cottages and ADUs. This draft legislation is published for SEPA review purposes and reflects the many comments and suggestions we received during several months of outreach, Thank you to everyone who provided input on backyard cottages and accessory dwelling units (ADUs).

In January and February 2016 we co-hosted two public meetings with Councilmember Mike O'Brien. We received hundreds of comments and ideas about how we can make it easier for people to create backyard cottages and accessory dwelling units (ADUs). Read a summary of what we heard, and view meeting materials on our Project Documents page.

Since 2010, the City of Seattle has allowed backyard cottages, also called detached accessory dwelling units (DADU) in all single-family residential neighborhoods. However, as of December 2015 only about 220 DADUs had been constructed.

In 2014, the City Council adopted Resolution 31547 directing us to explore changes that would increase the number of ADUs and DADUs in Seattle. Since then, we have considered a range of changes that could make it easier to build a DADU or that would allow them on more lots. To understand the barriers to building new DADUs and options for removing them, we have been hearing from residents who have built, or would like to build, a DADU to learn about their experience. For more information, visit our Get Involved page.

Project Benefits

By encouraging more backyard cottages and ADUs, we can help increase the supply and variety of housing options in single-family neighborhoods. DADUs are a type of housing with many of the structural characteristics of a small single-family house: a single unit with no shared walls in a lower-density residential neighborhood. Due to their smaller size and lack of additional land cost, DADUs can be a more affordable housing option in neighborhoods where homes are often unaffordable.

DADUs are also a good housing option for a variety of households, including families with children and multi-generational households. Families can respond to changing needs for living space by adding a backyard cottage. Property owners can also rent their DADU to earn additional income that makes it easier for them to remain in a neighborhood when they might otherwise be priced out.

End Result

Once code barriers are removed, property owners will be able to more easily get a permit to construct a backyard cottage or ADU on their lot. This helps broaden the housing options available in single-family residential zones.

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