Middle Housing in Washington

This page shares guidelines and technical support materials for local governments in Washington required to address infill housing as a part of their comprehensive plan and development regulations. 

Graphic depiction of small houses to duplex houses all the way up to high rise apartments
Graphic depicting middle housing types that could be included in more diverse residential neighborhoods.

Middle Housing Overview

During the 2023-24 legislative session, HB 1110 (2023) was adopted to implement middle housing across the state.

Middle housing is a term for buildings that are compatible in scale, form and character with detached single-family houses. Examples include: duplexes, triplexes, fourplexes, fiveplexes, sixplexes, courtyard apartments, cottage housing, and townhomes. These building types are typically “house-scale”; that is, the buildings are similar in bulk and form as single-family detached houses.

Middle Housing Model Ordinances

RCW 36.70A.636(1) and (2) direct Commerce to provide technical assistance, including publishing model ordinances, to implement the middle housing legislation. The model ordinance(s) were required to be published by January 23, 2024.

The published model ordinances include both HB 1110 requirements, and optional development standards to facilitate middle housing development. Local jurisdictions may adjust optional standards not specified in HB 1110 based on local preferences. To account for differing middle housing requirements based on a city’s population, one model ordinance has been prepared to assist cities 25,000 in population and greater, and the second ordinance for those cities less than 25,000 in population.

A User Guide accompanies the middle housing model ordinances that provides background on the content of the model ordinances, link to resources and other guidance related to HB 1110 implementation.

Model Ordinances and User Guide:

Model Ordinance Development Process

Preparation of the model ordinances followed a public engagement process that included online open houses, focus group meetings, a public webinar, public comment period, presentations at conferences and a local government technical advisory committee. The following Middle Housing Public Engagement Report summarizes the public outreach process.

Forthcoming Model Ordinance update – summer 2024

In 2024, the Legislature passed HB 2321 (2024), amending part of HB 1110 (2023). Commerce will be updating the middle housing model ordinances and user guide to address these changes and also respond to issues raised since the January 2024 publication. 

Middle Housing and Accessory Dwelling Unit Empirical Parking Study Guidance

House Bill 1110 (Middle Housing) and House Bill 1337 (Accessory Dwelling Units) passed in 2023 set maximum off-street parking requirements that local governments may impose on middle housing and accessory dwelling units.

Both bills identify instances where the maximum off-street parking requirements would not apply. One of these instances is if a local government submits an “empirical parking study” to Commerce, which Commerce must then review and decide whether or not to certify (see RCW 36.70A.635(7) and RCW 36.70A.681(2)(b)(i)).

Both bills require Commerce to develop guidance to assist cities and counties on items to include in the empirical parking study. Commerce has hired the consulting firm of Toole Design to prepare empirical parking study guidelines for local governments to use in making a certification request to Commerce.

Schedule details and materials

Commerce formed a local government staff Technical Committee to review and provide feedback as Toole Design developed the draft parking study guidance and related documents. Technical Committee slide presentations are posted here:

Open Comment Period from May 22 – June 21, 2024

The draft empirical parking study guidance document is available for a 30-day public comment from May 22, 2024 to June 21, 2024.

  • Draft empirical parking study guidance (PDF) (Available May 22, 2024)
  • Draft empirical parking study application checklist (PDF) (Available May 22, 2024)

Submitting Comments

Please use our public comment form to submit comments.

  • Public Comment Form (Smartsheet)

Public Comment webinar on parking guidance

A public webinar to present the draft empirical parking study guidance document will be held on Thursday, May 30, 2024 from 3:00pm to 4:00pm.

Middle Housing Grants

The 2023-2025 State Operating Budget, SB 5187, directs Commerce to administer grants and provide technical assistance to cities or counties for actions relating to adopting ordinances that plan for and accommodate housing. Commerce has made approximately $4.5 million available in statewide grants to implement HB 1110 supporting the development of middle housing. 

In a recent press release, Commerce announced middle housing awards for 68 jurisdictions. Limited middle housing grant funds still remain to support middle housing implementation work. However, these funds must be spent by June 15, 2025. 

Accessory Dwelling Units (ADU) and Resources

While ADUs are not defined as middle housing, they provide infill housing that fit into residential neighborhoods. HB 1337 (2023) requires all local governments planning under the GMA to allow at least two ADUs per lot within urban growth areas, with some limitations. Final guidance and additional resources for local government planners are available here:

Additional Middle Housing

Middle Housing Tools

Before the adoption of HB 1110 (2023), Commerce developed information and tools to help local governments with an interest in middle housing. Please contact us if you need any of the following in an editable format.

Quick Links

Contact

For Middle Housing guidance and technical assistance, please contact: 

Dave Osaki, AICP 
Middle Housing Lead
Dave.Osaki@commerce.wa.gov

For ADU guidance and technical assistance, please contact:

Anne Fritzel, AICP
Housing Section Manager
Anne.Fritzel@commerce.wa.gov