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An aerial photo showing residential scale density and infill

Residential scale density with possible urban infill volume solutions in white.
Map data: Google
Diagram by Ariel Scholten

Seattle is plagued with the twin challenges of rapidly rising population growth yet persistently increasing housing shortages. Last year, as the Puget Sound Business Journal reported, the US Census found that the Seattle metro area gained over 1,000 people per week between 2010 and 2016. Meanwhile, according to the Seattle Times, as of April 2017 the median home price in Seattle had soared to $722,000. Our biggest difficulty is that these changes create a need for significantly higher density, while at the same time, a collection of neighborhoods are resisting healthy growth.

In Seattle, housing challenges range from homelessness to affordable housing availability. Renters who wish to buy must grapple with an expensive and increasingly competitive housing market, in part due to a scarcity of properties available for purchase. Nearly two-thirds of the city’s developable land is zoned for detached single-family homes, but all of that has already been developed, and we have no good mechanisms to infill additional for-sale dwellings. Where density is permitted, some people feel that it overwhelms adjacent neighborhoods with a lack of transition and appropriately scaled new buildings.

To address these issues, a variety of solutions warrant more attention, including the development of condominiums, cooperative housing, DADUs, and ADUs, or the modest upzoning of single-family residential neighborhoods to allow duplexes, triplexes, and row houses. These innovations don’t face design hurdles as much as urban planning and public policy barriers.

For example, even in neighborhoods where property owners wish to densify, zoning regulations cause tension and inhibit them from responding to the market. Seattle’s Wallingford neighborhood provides a case in point. Home to families, singles, and students (many of whom are longtime Seattle residents), Wallingford is known for early 20th-century craftsman-style houses, mixed-use residential zones, and an abundance of parks and schools. The neighborhood is currently facing increasing density in the form of higher-rise buildings, as well as proposals to upzone areas to accommodate multifamily structures, which some residents feel will compromise Wallingford’s scale and character. However, other neighborhood residents are thinking creatively and proposing an alternative to six-story zoning, whereby a larger area would be modestly upzoned with infill. For example, single-family zoning could be altered to allow limited infill, such as changing setback regulations, lot coverage rules, or lot subdivision limitations. These are all useful levers to increase density and affordability while simultaneously preserving the neighborhood’s character.

A diagram showing residential typology in Seattle's Wallingford neighborhood

Typical residential typology with modern urban infill in Seattle’s Wallingford neighborhood. Diagram by Ariel Scholten

This concept has roots in other parts of the world. Historically dense cities such as Amsterdam, Paris, Brussels, Boston, and Philadelphia have been able to achieve significant densities through four-story walk-ups and row houses. In Germany and East Asia, a technique called land readjustment is being used to densify existing development while accommodating current residents. Through readjustment, existing development is assembled into an “overlay” plot with new development retrofitted into the open spaces between buildings.

What would it take for ideas like these to be tested in Seattle? Through new regulations and guided procedures, homeowners in single-family residential neighborhoods could convene with neighbors, plan and subdivide plots, and infill side yards with newly built narrow homes. Current homeowners would see revenue from the projects while overseeing the development process, while new owners would have affordable housing solutions. Further, an array of different architecture types would pave the way for an evolved and increasingly eclectic neighborhood character, giving significance to the Seattle craftsman but weaving in new styles and technologies along the way. The urban fabric would strengthen and grow with the help of the community rather than continue to separate it.

The lack of affordable housing in Seattle is divisive and unsustainable. In contrast, the simple act of allowing for lot subdivision or readjustment, with active participation of property owners and their neighbors, can help promote responsible, forward-looking development. Creating more flexible frameworks for infill in single-family neighborhoods can unlock the door to creative and beautiful solutions, not just for the folks who live here now, but for all those who want the opportunity.