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EIS Report Confirms: Backyard Cottages Are Key to Building Inclusive, Multi-generational Neighborhoods

On Thursday, the Seattle City Council released the Final Environmental Impact Statement (EIS) that evaluates the potential environmental impacts of proposed changes to the City’s Land Use Code intended to remove barriers to the creation of accessory dwelling units (ADUs) in single-family zones (also known as backyard cottages or in-law apartments).

The results of the analysis indicate that all of the action alternatives would increase the production of ADUs citywide compared to the No Action alternative and would reduce the number of teardowns of single-family homes.  The Preferred Alternative analyzed in the Final EIS represents the changes Councilmember O’Brien intends to include in legislation he plans to introduce in early 2019.

ADUs are small secondary dwelling units inside, attached to, or in the rear yard of a single-family house. An attached ADU (AADU), often called an in-law unit or basement apartment, is contained within or attached to a single-family house. A detached ADU (DADU), often called a backyard cottage, is a separate structure allowed in the rear yard of certain single-family-zoned lots. DADUs can be new structures or created through conversion of an existing structure, like a garage.

The Environmental Impact Statement (or EIS), which commenced in October 2017, represents the capstone on a multi-year effort to explore policy changes that would spur creation of ADUs.

“Based on comments we received and the analysis that was conducted, we believe that backyard cottages will allow homeowners to increase the number and variety of housing choices in single-family zones,” said O’Brien, who now chairs the Council’s Sustainability and Transportation committee.  “What’s more, the addition of ADUs will afford homeowners and renters alike a mix of housing types at prices accessible to people at a variety of incomes. This includes family members who want to age ‘in place’, or increase their income through a long-term rental.”

In 2009, DADUs were allowed Citywide.  In 2015, Councilmember O’Brien directed city staff to explore policy changes that spur the development of more backyard cottages.

O’Brien added, “In just the last few years, I have heard from more than 200-plus Seattlites who are waiting and ready to build ADUs — and with the sound research and solid analysis that informed the final EIS, today we are one step closer to helping them attain that goal and make their dreams a reality.”

TIMELINE & Next Steps

  • Between 1900 and the 1950s, ADUs were commonly allowed under single-family zoning provisions. Gradually, this type of housing fell out of favor, and ADUs were no longer allowed in single-family zones.

  • 1994 Accessory dwelling units first introduced to Seattle. The city only allowed units that were attached or inside an existing home, such as an in-law suite.

  • 2006 Seattle allows backyard cottages, or detached accessory dwelling units, in Southeast Seattle.

  • 2009 Detached backyard cottages allowed citywide.

  • 2014: City Council adopted Resolution 31547 directing DPD staff, now at the Office of Planning and Community Development (OPCD), to explore policy changes that would spur creation of both ADUs and DADU

  • Sept. 2015: Councilmember O’Brien directs city staff to explore policy changes that spur the development of more backyard cottages in context of Mayor’s Housing Affordability and Livability agenda

  • May 2016: Office of Planning and Community Development evaluates potential environmental impact of proposed changes. Issues a determination of non-significance.

  • June 2016: The determination of non-significance is appealed.

  • Dec. 2016: Seattle Hearing Examiner calls for a full review of potential environmental impacts of the proposal.

  • October 2017: City begins to evaluate potential environmental impacts to proposed changes. From October 2 to November 16, 2017, we took input on what we should study in the EIS

  • May 10, 2018: City releases draft Environmental Impact Statement

  • May 10, 2018 – June 25, 2018: Public Comment Period on the draft EIS

  • October 4, 2018: Issue final EIS

Following the completion of this year’s Budget discussions, Council will embark on the process to craft legislation which will be informed by additional public comment opportunities.  The resulting council bill is expected to remove some barriers to building ADUs, including changes to off-street parking rules, owner-occupancy requirements, and design standards. With these policy changes, more backyard cottages and in-law apartments can be built throughout Seattle neighborhoods.

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