Shoreline will consider legalizing new duplexes and triplexes in all of its residential neighborhoods, though a decision won’t be made for many months and the details are still up for debate.

In a split vote Monday night, Shoreline’s City Council directed the city’s planning department to study and conduct public outreach about the potential change, which one leader described as a natural evolution for the suburb north of Seattle and another said could be a radical step.

Similar proposals are under discussion in cities across the region and at the state level; a bill that would have legalized “missing middle” housing like duplexes and triplexes near transit lines in communities throughout Washington failed in February after attracting widespread attention.

The planning amendment proposed by Shoreline Councilmember Chris Roberts would “explicitly allow duplexes and triplexes” on lots in the city’s low-density residential zones. Currently, only single-family houses are allowed on most lots in those neighborhoods, due to units-per-acre density limits (basement apartments and backyard cottages are also allowed, though only when the property owner lives on-site).

Shoreline’s planning department will analyze the potential change, both in terms of effects to the environment and in terms of policy options. The council could allow duplexes and triplexes on every lot or only in certain circumstances, said Jim Hammond, a city spokesperson. For example, the council could choose to allow triplexes only on corner lots, Hammond said. 

The planning department will also undertake an extensive public engagement process with a racial equity component, geared to involve people of all backgrounds and then make recommendations to the city’s planning commission, Hammond said. The commission, in turn, will hold public hearings and then make recommendations to the council.


All that will take months, if not years, said Steve Szafran, one of Shoreline’s senior planners. Planning amendments are normally sent to the council to approve or reject in November or December each year. But the proposed amendment is an unusually substantial one, so the planning department’s work may stretch into 2023, Szafran said.

Roughly 70% of Shoreline is currently zoned for low-density residential development, with apartments and businesses allowed near Aurora Avenue North, around the light-rail stations under construction at 145th Street North and 185th Street North, and in other select spots.

That means the amendment proposed by Roberts could, theoretically, triple the housing allowed on most lots in the city, Mayor Keith Scully said Monday.

Duplexes and triplexes are needed in Shoreline and in nearby communities because of a housing shortage in the region, Roberts said, with more than 40,000 additional units needed now and more than 800,000 needed by 2050, according to the Puget Sound Regional Council.

The council member described growing up near a duplex and living in a two-unit building during graduate school. Those structures blended in with single-family houses, he said. Shoreline can complement his high-level planning amendment with more technical development codes to ensure that new duplexes and triplexes in the city look appropriate, Roberts added, calling the change a natural evolution for Shoreline.

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The planning department advised the council to hold off on Roberts’ request and to instead study duplexes and triplexes as part of a major planning update due in 2024. That update will include other topics and “allow for greater public participation,” the department wrote.

Deputy Mayor Betsy Robertson opposed Roberts’ request, characterizing the idea as “not fully baked.” Mayor Scully backed the request, saying Shoreline needs to check out more housing options. But he said he would hesitate to support allowing duplexes and triplexes on every lot.

“This will be a different city if you start seeing triplexes popping up” in large numbers, Scully said. “Studying this to see if there’s a way we can do it without radically changing the city, for me, makes sense.”

The vote was 4-3, as councilmembers Eben Pobee and John Ramsdell joined Roberts and Scully in supporting the request. Councilmembers Doris Fujioka McConnell and Laura Mork joined Robertson in opposition.