If you’ve been hearing more conversations about “middle housing” in Seattle, House Bill 1110 is the reason why.

Passed by the Washington State Legislature in 2023, HB 1110 is a statewide effort to expand housing options in neighborhoods that have traditionally allowed mostly single-family homes. The goal is simple but significant: create more housing choices, increase affordability over time, and allow cities to grow in a way that better matches today’s needs.

So what does that actually mean for Seattle?

Under HB 1110, the City of Seattle is required to update zoning rules in many residential areas, specifically those currently classified as Neighborhood Residential (NR) or Residential Small Lot (RSL). These updates will allow a wider range of housing types on lots that previously allowed just one home.

Instead of only detached houses, the city must now allow “middle housing.” This includes options like duplexes, triplexes, fourplexes, townhomes, cottage-style homes, stacked flats, and small courtyard-style apartments. The law requires cities to allow at least four homes on every residential lot. In areas close to major transit stops, or where some homes are set aside as affordable units, that number increases to six.

The bill also aims to reduce common barriers that have historically made it difficult to build these types of homes. That includes streamlining design review, limiting parking requirements, and adjusting development standards that can unintentionally block smaller-scale multi-unit projects.

Seattle has until June 30, 2025, to bring its zoning into compliance with these new state requirements.

To do that, the city is rolling HB 1110 into a broader planning effort called the One Seattle Plan. Led by the Office of Planning and Community Development, this comprehensive plan looks ahead 20 years and focuses on how Seattle can grow while improving housing supply, affordability, and neighborhood inclusivity.

Beyond adding housing, the One Seattle Plan also addresses equity. It acknowledges the city’s history of exclusionary zoning and discriminatory practices like redlining, and it aims to make neighborhoods more accessible across income levels and backgrounds. Allowing more housing choices in more areas is a key part of that effort.

In the coming months, the city will release draft updates outlining how Neighborhood Residential zones may change to meet the requirements of HB 1110. These drafts will be followed by public comment periods, community meetings, and additional opportunities for residents to weigh in before anything is finalized.

Later phases will include proposed zoning maps and specific legislation that spell out exactly how these changes will be written into city code.

For homeowners, buyers, and investors, HB 1110 represents a meaningful shift. It opens the door to more flexible use of residential property, encourages gentle density near transit, and reflects a growing emphasis on walkable, connected neighborhoods.

As Seattle continues to evolve, this legislation marks a step toward a housing landscape that offers more options while shaping a city designed for the long term.

This post was based on information found on The City of Seattle.