Middle Housing in Washington

This page shares definitions, guidelines and technical support materials for local governments in Washington with an interest in pursuing middle housing as a part of their comprehensive planning and local 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 single-family neighborhoods.

Middle Housing Overview

Middle housing is a term for homes that are at a middle scale between detached single-family houses and large multifamily complexes. Examples include: duplexes, triplexes, fourplexes, fiveplexes, sixplexes, courtyard apartments, cottage clusters, and townhomes. These types are typically “house-scale”; that is, the buildings are about the same size and height as detached houses. During the 2023-24 legislative session, HB 1110 (2023) was adopted to implement middle housing across the state.

HB 1110 (2023) Middle Housing Model Ordinances

HB 1110 (2023) directs Commerce to provide technical assistance including model ordinances, for implementing the bill.

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

The User Guide provides background on the content of the model ordinances and also provides additional guidance related to HB 1110 implementation.

Publication of the model ordinances follows a public engagement process. Public engagement included focus groups, a technical committee comprised of city planning staff, online open houses, presentations at conferences and other public events, and a public webinar that accompanied a 30-day public comment period. 

MAKERS Architecture and Urban Design has been selected to lead a team to develop middle housing model ordinances with the Department of Commerce, supported by Kimley-Horn, ECONorthwest and Ogden Murphy Wallace. The model ordinances will be shaped by stakeholder engagement along with the team’s expertise in middle housing policy, land use planning, development regulations and economic analysis.

Current project materials:

Final Versions – Model Ordinances (January 23, 2024)

Model Ordinance Development Process

Middle Housing Ordinance documents – 30 day comment period (November 6 – December 6, 2023)

Middle Housing Model Ordinance Workshop Materials

Model Ordinance Development Schedule

House Bill 1110 requires Commerce to publish model ordinances by January 23, 2024. 

The illustration below summarizes the process and timeline that went into preparing and publishing the model ordinances. 

Public Outreach

Schedule details and materials

The time frame to publish the final model ordinances was brief; however, community engagement will be part of the process and included, as examples, the following:

In addition to the above, Commerce held several online drop-in open houses where the public visited, asked questions and offered comments on HB 1110.

The public engagement process will be summarized in the form of a public engagement report to be published and posted on this webpage.

If you would like to receive more information on the Model Ordinance process, please sign up for our mailing list using this online form.

Middle Housing Grants


The 2023-2025 State Operating Budget (Senate Bill 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 will make approximately $4.5 million available in statewide grants to implement House Bill 1110 (2023) supporting the development of middle housing. One round of funding is complete and a second round has just started.

Grant window open

Commerce has opened a second round with applications due on Nov. 22, 2023 at 5 PM and then on a rolling basis as funds remain available. This second round will be for the remaining $1.5 million available to implement HB 1110 (2023). Completed application should be submitted to gmsgrants@commerce.wa.gov by the deadline. Please see the following materials and guidance for grantees.

Application Materials 

Commerce hosted a pre-application workshop in August. The following materials and video recording of the workshop may be found here. 

Grant requirements

Middle Housing grants are available to cities and counties that are subject to the requirements of HB 1110 (2023) during their next periodic review update cycle (2024-2027) under the Growth Management Act.

Cities and counties not subject to HB 1110 may also apply for activities related to implementing middle housing. However, priority for grant funding is reserved for communities required to implement. 

Maximum grant amounts are between $35,000 and $75,000, and they are dependent on population and whether the community received funding from the 2021-23 Middle Housing Grant program. 

Accessory Dwelling Units (ADU) and Resources

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

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.