What Does HB 1110 (“Middle Housing”) Actually Mean for Your Neighborhood?

If you live in a city or suburb across Washington State, you’ve likely heard about House Bill 1110. Passed by the legislature to address our chronic statewide housing shortage, HB 1110 effectively lifts single-family-only zoning restrictions in most major urban centers.

While headlines often announce “the end of single-family zoning,” the reality on the ground is much more subtle, deliberate, and evolutionary.

As a housing economist, I analyze real estate trends through price elasticity, capital flows, and demographic shifts rather than neighborhood rumor mills. Here is what HB 1110 actually does, what it doesn’t do, and how it will transform local communities over the next decade.

The Mechanics: What Is HB 1110?

HB 1110 requires Washington cities planning under the Growth Management Act (GMA) to allow “middle housing” on lots previously restricted to single detached homes. Middle housing includes duplexes, triplexes, fourplexes, fiveplexes, sixplexes, townhomes, stacked flats, courtyard apartments, and cottage housing. Larger cities must allow at least six of these nine types, while the smallest covered cities must allow at least four.

The state establishes a tiered framework based on population and proximity to transit:

To prevent cities from using soft barriers to block these homes, HB 1110 limits off-street parking mandates and requires design review to be administrative rather than subject to lengthy public review boards.

Timing and local flexibility. Cities don’t all move at once. Each must comply shortly after its periodic comprehensive plan update, so deadlines are staggered by region. Most central Puget Sound cities came under the requirements in mid-2025, and other regions follow on later schedules. A city that misses its deadline doesn’t escape the law. The state’s model ordinance takes effect directly until local rules are adopted. Cities may also apply the density requirements to at least 75% of qualifying lots rather than every lot, subject to limits on which areas can be excluded. That flexibility is one reason implementation can look different from one neighborhood to the next.

Myths vs. Market Realities

There is widespread confusion about how HB 1110 will unfold in practice. Three common misconceptions deserve a closer look:

Myth 1: Single-family homes are now illegal.Reality: HB 1110 dictates what a city must allow, not what a property owner must build. Property owners retain the right to construct, remodel, or sell traditional detached single-family homes.

Myth 2: Neighborhoods will be bulldozed overnight.Reality: Redevelopment moves incrementally. In Oregon and California, which passed similar reforms earlier, middle housing projects have replaced only a small fraction of a percent of eligible lots each year. In a typical neighborhood of 1,000 homes, that translates to a handful of infill projects annually, not wholesale transformation. Land prices, construction costs, financing, and lot configuration all limit how many parcels actually pencil out and in many instances, the math doesn’t work.

Myth 3: HB 1110 overrides every private deed restriction.Reality: It doesn’t. Homeowners association governing documents created after the law took effect in July 2023 cannot prohibit middle housing. However, HB 1110 does not reach back to rewrite covenants recorded before then. Many older single-family plats carry Covenants, Conditions, and Restrictions (CC&Rs) that limit a lot to one detached home, and those can still block multi-unit projects on those parcels. (If you’re considering a middle housing project, check your title report before you check the zoning code.)

The Neighborhood Impacts: What to Expect

A Shift Toward Infill Ownership Option

The primary target of middle housing is young families, downsizers, and local workers who are priced out of single-family homes but don’t want to live in high-rise apartment complexes. Cities complying with HB 1110 must also allow unit lot subdivisions. These let developers build attached townhomes or duplexes on a single parcel and sell each unit separately as fee-simple ownership.

Instead of a single lot selling one house for $1.1 million, that same lot might host three townhomes priced at $600,000 each, providing a lower entry point into competitive neighborhood housing markets.

Minimal Infrastructure and Parking Volatility

A primary concern among residents is street parking and traffic congestion. However:

• Lots within ½ mile walking distance of a major transit stop are exempt from mandatory off-street parking requirements, encouraging transit use.

• Outside those areas, lots of 6,000 square feet or less can be required to provide no more than 1 parking space per unit, while larger lots are capped at 2 spaces per unit.

  
  

Long-Term Moderation of Property Values

There is little evidence that middle housing pulls down the value of existing homes. In fact, single-family lots with favorable zoning and flat topography often see land values rise because developers will pay a premium for multi-unit development potential. What middle housing does do, over a 10-to-20-year horizon, is slow the rate of regional price appreciation by adding needed housing supply.

What This Means for Homeowners and Buyers

 If you own a single-family home: You gain development flexibility, provided your lot isn’t restricted by older covenants. You might build a duplex to live in one unit and rent the other, create space for aging parents, or eventually sell to a builder at a potential land premium.

If you are trying to buy a home: You will see a broader diversity of listings over time. Townhomes, cottage courts, and triplexes offer opportunities to buy in desirable, walkable neighborhoods near strong schools and amenities without paying single-family peak prices.

The Bottom Line

HB 1110 is not a magic wand that will solve Washington’s housing affordability crisis overnight, nor is it a threat to single-family neighborhoods.

Instead, it is a structural zoning reform designed to restore “gentle density.” Over time, it allows our cities to grow organically, adding context-sensitive housing choices, supporting small local businesses, and giving the next generation of Washingtonians a realistic path to housing stability.

What questions do you have about how your specific city or neighborhood is implementing HB 1110?