Planning for Middle Housing

Middle housing is intended to be compatible with single-family neighborhoods while providing more dwelling units per lot. It supports housing affordability and increases housing stock while generally utilizing existing infrastructure. The following documents replace the prior January documents which can be requested from Commerce.

• Middle Housing Update Deadlines (PDF)
• User Guide for Middle Housing Model Ordinances (PDF)
• Model Ordinance for cities 25,000 and over (PDF)
• Model Ordinance for cities under 25,000 (PDF)
• Middle Housing resources on EZView (EZview.wa.gov)
• Middle Housing Checklist (Word)

For those communities seeking a time extension or the use of the substantially similar alternative for compliance, please utilize the following. The guidance in the Fact Sheets is interim, until such time the Washington Administrative Code (WAC) update addressing housing bills is adopted in early 2025. The adopted WAC will identify the final alternative pathway review and application processes.

• Time extension to address displacement fact sheet (PDF)
• Time extension due to lack of infrastructure capacity fact sheet (PDF)
• Substantially similar alternative (PDF)

Jurisdictions making an application to Commerce for a time extension certification or substantially similar approval referenced above must complete and submit the following application form and applicable checklist with their application. The check boxes in the application submittal checklists are to be used to confirm that all required information is provided with the application.

• Application form (Word)
• Application checklist – Time extension to address displacement (Word)
• Application checklist – Time extension to address infrastructure capacity (Word)
• Application checklist – Substantially similar alternative (Word)

While ADUs are not defined as middle housing, they provide beneficial infill housing which fit into residential neighborhoods. Furthermore, two (2) ADUs are required to be permitted on lots within urban growth areas, with some limitations.

ADU resources

• ADU Guidance (PDF)
• ADU Checklist (Word)
• More Accessory Dwelling Unit (ADU) Materials (EZview.wa.gov)

Certain residential uses (i.e. middle housing, ADUs, co-living) have standards related to the amount of parking that may be required. In addition, improvements to parking areas that serve residential development are subject to certain requirements.

• Residential Parking Checklist (Word)

Empirical parking study guidance

Both Middle Housing and Accessory Dwelling Unit requirements include options for developing an empirical parking study to determine appropriate parking requirements (outside of the requirements of state statute). The following documents provide guidance to local governments in developing an Empirical Parking Study and in making a certification request to Commerce.

• Draft empirical parking study guidance (PDF)
• Draft empirical parking study application checklist (PDF) 

Neighborhood infill development guidance is provided to assist cities in proactively understanding public works, engineering, and infrastructure issues as redevelopment occurs. The neighborhood infill development guidance addresses potential barriers to the development of neighborhood infill housing, provides examples of proactive solutions, and provides resources for planners to lead discussions with service providers.

• Neighborhood Infill Guidance – Related Disciplines

Manufactured/mobile home communities (MHCs) are residential areas that house multiple manufactured or mobile homes with shared infrastructure and amenities.

As communities across the state plan for housing that meets the needs of all income segments, they should take a careful look at this naturally occurring source of affordable housing.

Commerce has prepared the following guide to help local governments consider preserving this housing type.

• Manufactured/Mobile Home Community Preservation for Local Governments

• General Middle Housing FAQ (PDF)
• Jurisdictions subject to Chapter 332, Laws of 2023 (PDF)
• Middle Housing Building Types (PDF)
• Middle Housing Lot and Block Models (PDF)
• Middle Housing – Introduction (PPT)
• Middle Housing Study (PPT)
• Middle Housing – What, How and Where? (PPT)
• Middle Housing – How Do We Get More? (PPT)
• Middle Housing Summary of Resources (PPT)
• Middle Housing Presentation Videos
• Middle Housing appraiser engagement FAQ (PDF)

• Middle Housing Pro forma: Puget Sound Region Final (Excel)
• Middle Housing Pro Forma: Feasibility Attainability Slides (PDF)
• Middle Housing Pro Forma: Presentation Recording
• Appendix A: Middle Housing Market Assessment (PDF)
• Appendix B: Pro Forma Calibration and Assumptions (PDF)
• Appendix C: Middle Housing Pro Forma User Guide (PDF)
• Appendix D: Middle Housing Sensitivity Testing (PDF)

• Middle Housing Placetype Atlas (PDF)
• Middle Housing User Guide (PDF)
• Middle Housing Objective Design  Standard Basic Toolkit (PDF)
• Middle Housing Objective Design Standard Detailed Toolkit (PDF)