Summit Law Blog

Washington has been grappling with a housing shortage for years, as home prices and rents continue to outpace income growth. To help address the crisis, Washington passed House Bill 1110, often referred to as the “middle housing” bill, in 2023.

What is HB 1110?

HB 1110 requires many cities, including Seattle, to allow a wider range of housing types in areas traditionally reserved for single-family homes. These include duplexes, triplexes, fourplexes, fiveplexes, sixplexes, townhomes, stacked flats, courtyard apartments, and cottage housing.

The bill introduced a tiered system for what cities should allow based on their population and location:

• Tier 1 Cities | Population: 25,000 - 75,000
  • 2 dwelling units per lot
  • 4 dwelling units per lot within 1/4 mile walking distance of a major transit stop
  • 4 dwelling units per lot if at least one unit is affordable housing 
• Tier 2 Cities | Population: 75,000+
  • 4 dwelling units per lot
  • 6 dwelling units per lot within 1/4 mile walking distance of a major transit stop
  • 6 dwelling units per lot if at least two units are affordable housing 
• Tier 3 Cities | Population: under 25,000 and located in an urban growth area where there is another city with 275,000+
  • 2 dwelling units per lot

How Will HB 1110 Be Implemented?

Although HB 1110 officially took effect on July 23, 2023, most cities are only beginning to see its impact. This is because the law requires local governments to adopt new middle housing ordinances within six months of completing their next comprehensive plan update, as mandated by the Growth Management Act (GMA). In other words, cities couldn’t immediately change their zoning laws when the bill passed—they had to update their long-term plans first. Jurisdictions like King, Snohomish, and Pierce County finalized their updates in December 2024, which means new zoning ordinances are expected by mid-2025. Other parts of the state will follow on a staggered timeline, with some updates not due until 2026 or 2027.

The Benefits of HB 1110

HB 1110 is widely seen as a major step toward addressing Washington’s housing affordability crisis. By legalizing middle housing in areas traditionally reserved for single-family homes, the bill opens the door to more diverse, lower-cost housing options. This approach can help increase supply, reduce pressure on rents and home prices, and make it easier for first-time homebuyers, renters, and multigenerational families to find homes in desirable neighborhoods.

Beyond affordability, HB 1110 advances walkability, sustainability, and social equity by promoting compact, transit-oriented development and reversing decades of exclusionary zoning practices that have fueled racial and economic segregation. The bill also empowers property owners, giving them greater flexibility to develop their land and potentially generate additional income.

Challenges and Criticisms of HB 1110

Despite its promise, HB 1110 faces pushback and implementation hurdles. Some cities and residents are concerned about losing local control over zoning decisions, increased traffic and parking demand, and the potential strain on infrastructure such as sewers, schools, and utilities. Critics also argue that simply allowing more units doesn't guarantee affordability. Overwhelming infrastructure could lead to potential increases in utility fees for residents, increasing the cost of living rather than reducing it.

Without additional subsidies or tenant protections, new middle housing could still be priced out of reach for many. Additionally, in many wealthier or historically exclusionary neighborhoods, resistance to change remains strong, with fears that increased density could alter the character of the community or affect their property values.

Takeaway

HB 1110 marks a significant change in Washington housing. While it may not necessarily completely remove single-family zoning, it certainly is a step towards reshaping neighborhoods to allow for more diverse and affordable housing options. Its success will depend on effective local implementation, adequate infrastructure planning, and policies that ensure affordability.

Resistance from some communities and the risk of unintended consequences remain challenges, but HB 1110 lays important groundwork for a more inclusive and sustainable housing future in Washington.