In a move that promises a profound reshaping of the city's housing landscape, Seattle officials are in the process of dismantling decades of single-family zoning to comply with landmark state legislation aimed at addressing Washington’s housing crisis.

Driving the change is a sweeping 2023 state law that effectively ended traditional single-family zoning in many of Washington's cities. The law requires municipalities, such as Seattle, to permit a wider variety of "middle housing"—including duplexes, townhouses, and fourplexes—on all residential lots.

The city’s ambitious "One Seattle Plan" serves as the blueprint for this transformation. However, the path from a state mandate to a local reality has been a complex negotiation involving legal deadlines, neighborhood concerns, and the urgent need for more housing. While an interim plan is in place, a broader permanent version is expected to receive final approval in the remaining months of this year.

This change reflects a nationwide trend of cities legalizing "missing middle" housing to ease their affordability crises. The push for density consistently sparks fierce local opposition, creating a tense showdown between the need for new homes and the powerful desire to preserve neighborhood character.

California, which faces an even more severe housing crisis, is a prime example of this struggle, as cities there actively contest state-mandated density increases at the behest of neighborhood groups.

Seattle’s Housing Crisis

Seattle’s home prices and living costs rank among the highest in the United States. The city's robust economy, driven by major tech companies, has fueled high demand for housing; however, the supply has not kept pace, resulting in soaring prices.

As of this year, Seattle's cost of living is approximately 45% higher than the national average. Housing is the primary driver, costing over 109% more than the U.S. average, according to data from the Council for Community and Economic Research.

The national housing advocacy group Up for Growth calculated last year that the Seattle region had a housing deficit of more than 71,000 units.

Abiding by the Law

Under the Washington law, cities had until June 30 to update their comprehensive zoning plans. Seattle began work on its plan last year.

The One Seattle Plan takes that type of deliberate and tailored approach—bringing a greater diversity of housing types to every neighborhood, uplifting the voices of neighbors and vulnerable communities, and building a city where teachers, baristas, and working families can afford to live," Seattle Mayor Bruce Harrell said when the first draft was announced last March.

During his State of the City address in February this year, Harrell said the proposal would double Seattle’s zoning capacity and create at least 120,000 homes.

This is the most ambitious comprehensive plan update in our city’s history, and it is also the most necessary to deliver needed housing diversity and capacity at a scale that will make a difference,” he said.

Faced with a critical deadline to comply or have a state-designed model ordinance forced upon them, the Seattle City Council took a crucial first step in May, passing a "bare-bones" framework to meet the state's minimum requirements. With that vote, building four homes became legal on any residential lot across the city, and sixplexes were permitted near frequent transit routes.

Potential Upzoning Impact

Upzoning isn't new to Seattle. In the 1990s, the city upzoned select areas to create “urban villages” with new development. Most of the higher density was concentrated in southeast Seattle, while the rest of the city saw little to no upzoning.

This experience provides a real-world model for the potential effects of the city's current, more expansive, rezoning efforts.

A Seattle case study of urban villages published in September found that allowing low-rise multifamily zoning boosted the housing supply by 2.5% annually in affected markets. Over the past 30 years, replacing single-family homes with townhomes has created more than 20,000 new units, providing more affordable homeownership options for a younger, more diverse population, according to a study by American Enterprise Institute fellows Tobias Peters, Edward Pinto, and Joseph Tracy.

To fully realize the benefits of rezoning and increase housing supply effectively, policymakers must carefully consider the impact of other restrictive policies,” they wrote. “While zoning reforms are essential for addressing housing shortages, they must be implemented in a way that minimizes regulatory barriers and allows for the efficient development of higher-density housing.”

A Path to Permanence

While celebrated by housing advocates as a historic rezoning, Seattle’s temporary measure was just the prelude to a much more detailed and contentious debate over the city's permanent legislation.

That permanent plan is where the real work lies. It's not just about allowing more units; it's about defining the future character of Seattle's neighborhoods.

As Harrell transmitted the proposed permanent legislation to the City Council, the complexities emerged. The Select Committee on the Comprehensive Plan began wading through the details, balancing the state's density mandate against local priorities.

Opposition has been particularly sharp against the designation of new "Neighborhood Centers," which are intended to be zones of increased density and commercial activity around transit. Groups have mobilized in numerous neighborhoods to fight this designation.

Debates also intensified over development standards. An early proposal to retain the large front and rear yard setbacks typical of single-family homes was met with fierce opposition from housing advocates and builders, who argued such rules would make it economically impossible to construct the newly allowed multiplexes.

A compromise was eventually reached, reducing setbacks for lots with more units. Other critical issues, including the preservation of the city’s tree canopy and potential affordability requirements, remain central to the ongoing discussions.

As of October, the interim law is in effect, but the final shape of Seattle's housing future is still being forged in council chambers. The Select Committee is deliberating on the permanent legislation, with a final vote anticipated before the end of the year.

The initial rezoning may have been the easy part; the much more challenging task is crafting a permanent plan that guides how Seattle will grow into a denser, more affordable, and equitable city over the next 20 years.