In July 2023, Washington State enacted House Bill 1110, a transformative step in tackling the state’s housing crisis by allowing “middle housing” — duplexes, triplexes, fourplexes, sixplexes, townhomes, courtyard apartments and cottage housing — in areas traditionally zoned for single-family homes. All of these changes have understandably caused some confusion as cities across the region work to comply.
Seattle King County REALTORS®, in partnership with Washington REALTORS®, has been hard at work creating a stand-alone website, REALTORS®+Housing, aimed at helping brokers navigate the zoning changes across the four Puget Sound counties: King, Snohomish, Pierce and Kitsap.
What the law mandates
HB 1110 sets a tiered zoning mandate based on city population and proximity to transit:
- Cities 25,000 to 75,000: Duplexes allowed on all lots; fourplexes required within a quarter mile of transit or when one unit is affordable.
- Cities over 75,000: Fourplexes permitted statewide; sixplexes near transit or if two units are affordable.
- Under 25,000 (urban growth areas near major metros): At least duplexes statewide.
The law also eases parking mandates near transit — no minimum parking within half a mile and capped at one spot per unit on smaller lots.
Anticipated benefits
1. Expanded housing supply
By allowing additional units per lot, HB 1110 works to boost housing stock — a critical strategy to slow escalating rents and home prices.
2. Housing diversity and affordability
“Missing middle” housing offers more accessible entry points for renters, first-time buyers, seniors and multigenerational families.
Encouraging higher density near transit promotes walkability, reduces car dependency and carbon emissions and dismantles exclusionary zoning — a legacy of racial and economic segregation.
3. Economic and social gains
More homes near urban centers support local builders and enhance quality of life by offering more diverse, affordable housing types, which allow for residents to live and work closer together.
What brokers need to know
Effective growth management policies are essential to maintaining vibrant, livable communities. HB 1110 is a major step towards solving Washington’s housing crisis. Brokers should know the city’s overall zoning but should dial in on the individual lot’s feasibility. Remember, just because a lot is zoned a certain way does not mean the maximum allowable units are feasible on that lot.
Brokers should avoid generalizations and avoid promising what a site can accommodate. Some of the issues that potentially limit the amount of units on a site include:
- Covenant codes and restrictions that are recorded on title (sometimes prohibit splitting the lot or putting multiple structures on the site).
- Utilities — availability and accessibility (costs associated may be prohibitive); septic, wells.
- Fire codes.
- Environmental issues (trees, wetlands, geologic hazards, slopes, etc.)
- Access issues/irregular lot shapes.
Additionally, brokers should have their list of trusted advisors that can help clients determine the viability of additional units on the property. These include attorneys, planners, engineers and architects who have specific knowledge that will help determine the feasibility of the property.
In the coming weeks, SKCR will be creating a feasibility checklist of things to consider when shopping potential to clients. You will be able to find the checklist on the REALTORS®+Housing website.
Brenda Nunes is a member of Seattle King County REALTORS®.