On June 30, Seattle’s new rules for neighborhood zoning will take effect, allowing four to six units of housing on lots that once allowed only a standalone single-family house. The change brings Seattle into compliance with the Washington State Legislature’s 2023 “missing middle” zoning law.
The goal is to encourage development that’s denser than a single house per lot, but less dense than an apartment complex, to provide some of the 112,000 new units of housing Seattle’s projected to need by 2044.
The hope is that the duplexes, cottage apartments and other “missing” housing types allowed by the rezone will cost less to buy and rent than single-family homes. In Seattle, single-family homes currently sell for an average of $969,000, according to Zillow.
Under Seattle’s new law, adopted by the City Council on May 27, developers can build up to four units of housing on any residential lot. They can build up to six units on lots within a quarter-mile of major transit stops.
In addition, developers can build up to six units if two of the units are sold or rented at below-market rates. Experts say it’s unlikely many market-rate builders will use the affordable-housing bonus since they need market-rate prices to make their project costs pencil out, but nonprofit developers like Habitat for Humanity could use it to build more homes.
The law passed in May is actually an interim rezone set to expire in a year. Thanks to a cascade of delays, including legal challenges to the broader comprehensive plan update, the city was up against the state’s July 1 deadline for implementing missing-middle zoning.
The interim law is not drastically different from the proposed permanent changes. The permanent version does allow more than six units of housing on larger lots: A 10,000-square-foot lot, for example, could have up to eight units. The proposed permanent version also includes additional incentives for affordable-housing developers as well as for construction of stacked flats, which are essentially small apartment or condo buildings with one unit per floor. (Think Boston’s famed triple-deckers or Chicago’s two-flats.)
The change from one home to four per lot may sound dramatic, but Seattle already allows three units on any lot with the addition of two accessory dwelling units. Nonetheless, the missing-middle rezone is a significant change to land use that will help transform the city’s neighborhoods.
Cascade PBS spoke to developers and architects who specialize in missing middle-scale projects to get a sense of the impact the new zoning will have and what kind of housing Seattle can expect under the new rules.
What will get built?
The interim missing-middle law allows for nine types of housing. Five of them are “plexes” ranging from two-unit duplexes up to sixplexes. It also allows cottage apartments, which are typically small one- or two-story buildings that ring a central courtyard, and cottage houses, which are small detached single-family homes. The final two housing types are townhomes, which are already prevalent in Seattle’s low-rise zones, and stacked flats.
Though the vision of the state missing-middle law is to encourage a variety of housing types, architect Geoff Piper expects Seattle’s new missing-middle zoning to produce mostly detached townhomes similar to the ones already being built. Piper is a principal and owner at Fivedot, an architecture firm that specializes in residential and small-scale commercial projects and designed one of Seattle’s pre-approved backyard cottage plans.
“The conversations we’ve had with smaller-scale developers is there’s still a cultural and market preference for [standalone] housing,” said Piper. “We have three projects where we’re essentially building 1,000-1,200-square-foot separate buildings with three to four [buildings] on a lot.”
Josh Cohen
Matt Hutchins agrees that the new development standard encourages townhomes, which he expects will be what primarily replaces single-family homes in Seattle. Hutchins is a principal at CAST Architecture and a longtime housing advocate.
“On one hand that’s great for just overall supply and getting as much new housing out there as we can,” Hutchins said. “On the other hand, it’s not necessarily the highest and best use for some of these sites. What we really want is diversity of housing options, and townhouses don’t serve 100% of people. Because of stair access and an aging population, we need to have a mix of housing.”
Neither Piper nor Hutchins expect many, if any, stacked flats to be built under the interim zoning rules. Hutchins’ firm designed a six-unit, stacked-flat-style project in Spokane which adopted a missing-middle rezone in 2022 with less-restrictive rules about building size.
CAST’s Spokane project has two two-bedroom units on each floor of a three-story building. Under the state’s model missing-middle code, which Seattle’s interim rezone follows, the project would have to be 21% smaller, reducing each unit to one bedroom, and making the project financially unfeasible for developers.
Piper said that from an architectural standpoint, designing a 1200-1400-square-foot single-floor home is more ideal than a skinny, three-story townhome with lots of stairs.
The proposed permanent missing-middle legislation includes some incentives for stacked flats on larger lots, but Piper and Hutchins are hoping the City Council goes further to encourage development beyond townhomes.
The end of single-family homes?
The city’s new missing-middle zoning eliminates the requirement that developers build only a single home on most lots in Seattle. But Piper said single-family homes won’t be disappearing any time soon.
There’s still market incentive for standalone single-family homes, since many people still prefer them over a home with shared space, he said. And beyond that, it doesn’t make financial sense to tear down existing structures to build new missing-middle housing on every lot.
“It’s not like one neighborhood is going to get blown apart or, you know, one street could change all that much,” said Piper. “It’s going to be slow. I think people are overestimating the quantity and the speed at which this is going to happen.”
He said a larger lot with a small, aging post-War home on it is a likely candidate for redevelopment. Piper expects a property like that would make a good space for three or four townhomes that sell in the $650,000-to-$750,000 range. Not cheap, but less expensive than the $1 million-plus price tag of so many Seattle single-family homes.
Josh Cohen
When will developers start building?
For many developers and architects in Seattle, the uncertainty of the comprehensive plan delays and interim missing-middle law put new projects on hold. Hutchins said a townhome project can take 18 to 30 months from design to completing construction.
Potential builders don’t want to spend the time and money designing, permitting and constructing a new project when the zoning rules might change in the near future.
With the passage of the interim missing-middle bill, Piper thinks the logjam might start to clear. He said his firm had put four or five projects on hold while waiting for the interim rules to pass. Now that the law’s in place, those projects are moving forward, and his firm is getting interest from developer clients.
Other architects and developers are still feeling tentative, because the permanent missing-middle proposal allows for additional density on larger lots and additional incentives, and because the City Council could make further changes to the rules before the law is finalized. The Council intends to adopt the permanent version of the rezone this fall.
Leah Martin, a partner at design/build firm Allied8, said about 20% of her company’s projects remain in a holding pattern while they wait for the permanent legislation to work its way through the Council. The possibility that development code could change in the permanent legislation, leading to the added cost of revising the project design, is a risk not all clients are willing to take, said Martin.
“I wish they’d jumped in with both feet and passed the final rules,” Hutchins said of the City Council. “Having the interim step creates uncertainty. There’s a lot of potential development capacity they’ve left on the table for later.”
