‘Missing Middle Housing’ Bill Passes in Washington Senate

The legislation would permit duplexes and, in some cases, fourplexes in residential areas in most Washington towns.

1 minute read

April 12, 2023, 12:00 PM PDT

By Diana Ionescu @aworkoffiction


The Washington State Senate passed a bill permitting duplexes to be built in most Washington cities as part of the legislature’s effort to increase the housing supply and slow the rise of housing costs, reports Joseph O’Sullivan in Crosscut. According to O’Sullivan, “State officials estimate another 1 million housing units will be required in the next two decades to keep up with growth.” 

The bill requires localities with populations between 25,000 and 75,000 to allow duplexes in residential neighborhoods. The bill also permits fourplex construction in cities with over 75,000 people.

House Bill 1110, which was amended before the Senate vote, will go back to the House for a final vote. The bill is one of many pieces of zoning reform legislation proposed in Washington and other states that aim to boost housing production and remove barriers created by restrictive local zoning codes.

Tuesday, April 11, 2023 in Crosscut

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Cover CM Credits, Earn Certificates, Push Your Career Forward

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

June 11, 2025 - Diana Ionescu

Metrorail train pulling into newly opened subterranean station in Washington, D.C. with crowd on platform taking photos.

Congressman Proposes Bill to Rename DC Metro “Trump Train”

The Make Autorail Great Again Act would withhold federal funding to the system until the Washington Metropolitan Area Transit Authority (WMATA), rebrands as the Washington Metropolitan Authority for Greater Access (WMAGA).

June 2, 2025 - The Hill

Large crowd on street in San Francisco, California during Oktoberfest festival.

The Simple Legislative Tool Transforming Vacant Downtowns

In California, Michigan and Georgia, an easy win is bringing dollars — and delight — back to city centers.

June 2, 2025 - Robbie Silver

Color-coded map of labor & delivery departments and losses in United States.

The States Losing Rural Delivery Rooms at an Alarming Pace

In some states, as few as 9% of rural hospitals still deliver babies. As a result, rising pre-term births, no adequate pre-term care and harrowing close calls are a growing reality.

4 hours ago - Maine Morning Star

Street scene in Kathmandu, Nepal with yellow minibuses and other traffic.

The Small South Asian Republic Going all in on EVs

Thanks to one simple policy change less than five years ago, 65% of new cars in this Himalayan country are now electric.

6 hours ago - Fast Company

Bike lane in Washington D.C. protected by low concrete barriers.

DC Backpedals on Bike Lane Protection, Swaps Barriers for Paint

Citing aesthetic concerns, the city is removing the concrete barriers and flexposts that once separated Arizona Avenue cyclists from motor vehicles.

June 15 - The Washington Post