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

In May 2016, Councilmember Mike O'Brien released a draft proposal for removing barriers to backyard cottages and ADUs. Following this proposal, an appeal of the environmental review of this proposal was submitted. The hearing on this appeal began in August 2016 and concluded in December 2016. The Hearing Examiner reversed the Determination of Non-Significance (DNS) and directed us to prepare an Environmental Impact Statement (EIS) to analyze further how the proposal could potentially negatively affect the environment. The complete Findings and Decision document is available on the Hearing Examiner website.

We are currently reviewing the Examiner's decision and its implications. We are considering various options for this proposal, but we don't have any specific dates at this time.

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 backyard cottages and accessory dwelling units (ADUs).

Since 2010, the City of Seattle has allowed backyard cottages, also called detached accessory dwelling units (DADU) 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 it easier to build a DADU and that would allow them on more lots in Seattle. 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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