Councilmember O’Brien Unveils Bill to Encourage Backyard Cottages, Mother-in-Law Units
SEATTLE – Councilmember Mike O’Brien (District 6, Northwest Seattle) released a proposal today that would make it easier for more homeowners to build backyard cottages and mother-in-law units in Seattle. As the city faces an affordable housing crisis, Councilmember O’Brien developed the legislation to increase the housing supply by encouraging low-impact housing options that fit within the scale and character of Seattle’s single-family neighborhoods.
As of December 2015, 221 backyard cottages had been constructed or permitted in Seattle since Council authorized their use in 2009, despite approximately 75,000 single-family lots that are eligible to build one. Councilmember O’Brien heard feedback that current regulations put significant burdens on homeowners deciding to build backyard cottages or mother-in-law units.
Backyard cottages, also called detached accessory dwelling units (DADUs), are separate living spaces on the same property as an existing single-family house. Mother-in-law units, also referred to as accessory dwelling units (ADUs), are separate living units generally located within a single-family house. Both are currently allowed in single-family zones.
Councilmember O’Brien’s bill makes a series of changes to the existing backyard cottage and mother-in-law unit building code, including:
- Allowing both a backyard cottage and mother-in-law unit on the same lot, which provides additional housing options while maintaining the character and appearance of the property.
- Increasing the height limit for backyard cottages by 1-2 feet, depending on lot width, which would allow enough livable space to make two-bedroom units more feasible. Setback requirements from property edges would not change.
- Removing the requirement for owners to include an off-street parking space for backyard cottages or mother-in-law unit. Currently, this requirement often requires removal of green space on the property. Feedback found the parking requirement was prohibitive in creating new backyard cottages, as additional parking spaces were either unnecessary or unable to fit on the lot. For single-family lots outside urban villages or urban centers, the one required off-street parking space for a single-family house requirement will still apply.
- If a backyard cottage is only one-story, its floor area may cover up to 60% of the rear yard (currently 40%), creating a large enough livable space for those unable to use stairs. Existing setback requirements from the lot edge would not change.
- Requiring that the property owner live on-site for at least one year after a backyard cottage or mother-in-law unit is created, rather than the current requirement that the owner live on-site at least 6 months out of every year in perpetuity. The requirement prevents speculative developers from acquiring property and building backyard cottages that don’t fit the character of the neighborhood, while allowing the owner future flexibility for those who don’t want, or are unable to continue living on-site.
- Allowing backyard cottages on lots 3,200 square feet or greater in area (currently 4,000 square feet), which would make approximately 7,300 additional parcels eligible to provide this additional housing option.
- Increasing the maximum gross floor area of a backyard cottage to 1,000 square feet (currently 800 square feet), which would provide more livable area and increase the likelihood of two-bedroom backyard cottages to better serve families with children.
- If a backyard cottage is built above a garage, the garage square footage will no longer count toward the maximum floor area, which often results in an unreasonably small living space.
- Additional changes available here.
“With these amendments to the existing code, we could see thousands of new housing units that simultaneously fit into the context of a neighborhood and serve property owners,” said Councilmember O’Brien. “By expanding the availability of backyard cottages and mother-in-law units, someone might be able move to a neighborhood they otherwise couldn’t afford while helping a homeowner who needs an extra source of income to afford to stay where they are. It’s a win-win.”
The legislation was developed utilizing feedback from neighborhood community meetings, from architects, and from current backyard cottage owners. A summary of the public feedback is available here. The former Seattle Department of Planning & Development, now known as the Office of Planning & Community Development, also conducted an analysis of current backyard cottages in Seattle and a review of peer cities’ backyard cottage model.
“We primarily designed and built the space above our existing garage as a way of expanding our living space,” said Janice Reebs, a backyard cottage owner in the Sunset Hill neighborhood. “After reading the new proposed changes for backyard cottages, there are definitely some new rules which would have greatly benefited this particular project.”
“As someone who has designed both ground-up and garage conversion backyard cottages, and who created my own DADU, these code changes will make it much easier to design the most flexible spaces for homeowners who would like to create another housing unit on their property,” said Sheri Newbold, a backyard cottage architect at live-work-play.
The SEPA environmental determination on the draft proposal was published May 19, 2016. Comments may be submitted through June 2, 2016. The proposal is scheduled for consideration in the Council’s Planning, Land Use & Zoning Committee in July.
* Note: The News Advisory included building statistics as of October 2015. Through December 2015, 221 backyard cottages and mother-in-law units have been constructed or permitted, according to the Office of Planning & Community Development.
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Jasmine Marwaha, Councilmember Mike O’Brien’s Office, 206-684-8800
Dana Robinson Slote, Council Communications, 206-615-0061
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