Middle Housing (WA State House Bill 1110)

Recent Updates  

On June 23rd, the Marysville City Council adopted Interim Ordinances to address the requirements of Washington State’s House Bill (HB) 1110 on Middle Housing, HB 1337 on Accessory Dwelling Units, and HB 5258 on Unit Lot Subdivisions. The Interim Ordinances will be in effect until the fall of 2025 when final regulations are adopted. 

Public Hearings on the Interim Ordinances will be held before the Marysville City Council on Monday, July 14, 2025, at 7 pm at 501 Delta Avenue, 2nd Floor Council Chambers. For additional information, please review the notice linked to the right. Final regulations are being completed and will be considered by the Planning Commission on Tuesday, August 12, 2025, at 6:30 pm at 501 Delta, Avenue, 2nd Floor Council Chambers. 

Accessory Dwelling Units (WA State House Bill 1337) & Unit Lot Subdivisions (WA State House Bill 5258)

The City will also be adopting State-mandated regulations pertaining to Accessory Dwelling Units (House Bill 1337) and Unit Lot Subdivisions (House Bill 5258), which are also discussed on this webpage.

What is Middle Housing?

Middle housing is a range of housing types that include two or more attached, stacked, or clustered homes that are compatible in scale and form with detached single-family homes and neighborhoods. Middle Housing consists of a variety of housing types that are in between the size and number of dwelling units for single-family residences and apartments as shown in the image below.

Public Notice

  1. NOPH Final Regs Middle Housing ULS ADUs and Northpointe Rezone PDF.pdf
  2. NOPH Interim Ordinances - Middle Housing ULS ADUs (3).pdf
  3. Notice of Application- Middle Housing Amendment
  4. Open House - Middle Housing
  5. SEPA-DNS Middle Housing ADUs and ULS -CA23011 & CA25-0003

Jurisdictions in Washington State are required to allow at least six of the nine Middle Housing types listed below.*

Duplexes

Triplexes

Fourplexes

Fiveplexes

Stacked flats

Sixplexes

Courtyard apartments

Townhouses

Cottage housing

*Please note that the examples linked above are to provide a visual representation and general insight into Middle Housing. Specific local standards and architectural appearance will differ.

How many units are allowed on each lot?

Two to four units are allowed on each lot as outlined below.

HB 1110 breaks cities into three levels or “tiers” based on their population in 2020. The City of Marysville is a Tier 2 City meaning that it had a population of between 25,000 and 75,000 in 2020. By 2030, the City will transition to a Tier 1 City and will need to allow more units. Tier 2 cities are required to allow dwelling units as shown in the table below:

Lot circumstances Units allowed*
Lot zoned for residential use 2
Lot located within 1/4 mile walking distance to a major transit stop** 4
One unit is affordable housing*** 4

*A dwelling unit is a building, or a portion of a building, that has independent living facilities including a kitchen, sleeping, and bathroom facilities, and is designed for residential occupancy. The ‘units allowed’ in this table are the minimum density. If the zoning permit higher densities, than more units would be allowed.

**Marysville currently does not have a major transit stop in the city but will when Community Transit’s SWIFT Bus Rapid Transit comes to the City (estimated by 2029).

***To qualify for the one additional unit, the applicant must commit to renting or selling the required unit as affordable housing for a minimum of 50 years.

What else does HB 1110 (Middle Housing Statute) Require?

HB 1110 requires that cities:

  • Allow zero lot line short subdivisions if the number of lots created is equal to the density shown in the table above;
  • Ensure that development regulations are objective and that development regulations are not more restrictive than the regulations that apply to single-family units;
  • Modify off-street parking standards so that:
    • Off-street parking is not required for Middle Housing within one-half mile walking distance of a major transit stop;
    • Require only one off-street parking per unit for Middle Housing on lots less than 6,000 square feet (before any zero lot line subdivisions or lot splits); and
    • Require no more than two off-street parking spaces per unit for middle housing on lots greater than 6,000 square feet (before any zero-lot line subdivisions or lot splits).

Does Marysville already have Middle Housing?

While Marysville does not currently have all Middle Housing types, a variety of Middle Housing is present within the community. Some examples of existing and proposed Middle Housing include:

This duplex on Armar Road

These townhomes on Soper Hill Road

This cottage housing proposed near Sunnyside Boulevard

What are some of the benefits of Middle Housing?

While Middle Housing is not widespread in Marysville, it provides the following benefits:

  • Provides more ownership and rental housing options to meet different income and life-stage needs (e.g. young adults, families, single-person households, empty nesters, etc.);
  • Middle Housing provides an ownership option that is generally more affordable than a single-family residence and has fewer maintenance responsibilities;
  • Enables more housing units to be built on less land enabling the more efficient use of land and delivery of infrastructure such as water, sewer, and roads; and
  • It is a more compact development type that encourages homes to be located near amenities promoting walking, bicycling, and transit use.

Washington State’s HB 1337 establishes several new requirements for Accessory Dwelling Units. Accessory dwelling units are small houses that are accessory to single family residences. The key provisions of HB 1337 include: 

  • Allowing two accessory dwelling units accessory to single family residences.
  • Eliminating the owner occupancy requirement for accessory dwelling units. 
  • Allowing conversion of existing accessory structures to accessory dwelling units

What does HB 5258 (Unit Lot Subdivision statute) require?

Washington State’s HB 5258 (Unit Lot Subdivisions statute) requires that cities allow Unit Lot Subdivisions up to their short subdivision threshold for townhouses and other Middle Housing types. Unit lot subdivisions allow a parent parcel to be divided into smaller unit lots that are fee simple lots that can be owned separately. The setback, building, and impervious coverage allowances are based on the parent parcel. Divisions of land using the unit lot subdivision process can result in smaller lots than the general minimum lot size allowed for the zone. Unit lot boundaries can be drawn around structures or through the walls that separate a structure into individual units as shown in the images below. 

More information on Unit Lot Subdivisions is available HERE . 

Image of an example of a Unit Lot Subdivision with a duplex and accessory dwelling unit
Image of examples of Unit Lot Subdivisions with triplexes, cottage units, and townhouse units

What amendments are proposed to address the Middle Housing, Accessory Dwelling Unit, and Unit Lot Subdivision statutes?

Various amendments are proposed to the 2024 Comprehensive Plan and the Marysville Municipal Code (MMC) to address the Middle Housing (HB 1110), Accessory Dwelling Unit (HB 1337), and Unit Lot Subdivision (HB 5258) statutes. These amendments include, but are not limited to: 

  • Amending the MMC to allow two (2) dwelling units on all lots primarily designated for residential, and four (4) dwelling units on all lots primarily designated for residential when the property is either within ¼ mile of Community Transit’s Bus Rapid Transit (which is expected to arrive in the City around 2029), or when one designated affordable housing unit is provided.
  • Amending the MMC to allow the following Middle Housing types: duplexes, triplexes, fourplexes, townhouses, courtyard apartments, and cottage housing. Not proposed are fiveplexes, sixplexes, and stacked flats.
  • Reducing parking for Middle Housing uses to zero (0) parking spaces per unit for units located within ¼ mile of Bus Rapid Transit, one (1) parking space per unit for lots that are equal to or under 6,000 square feet, and two (2) parking spaces per unit for lots that are over 6,000 square feet as required by State law. It should be noted that a parking study is being conducted to potentially increase parking to ensure adequate parking and safety within residential areas; however, proposed parking increases are subject to Washington State Department of Commerce review and approval.
  • Allowing two accessory dwellings units accessory to single family residences. 
  • Eliminating the owner occupancy requirement for accessory dwelling units.
  • Adopting a Unit Lot Subdivision ordinance that allows for subdivision of a parent lot into nine (9) unit lots. Please note the total number of unit lots which will ultimately be allowed may potentially be increased.

To address the requirements of HB1110 and HB 1337, various supporting Comprehensive Plan and MMC amendments are needed. The most significant of these changes is the Comprehensive Plan map amendment and rezone of the R-4.5 Single Family Medium Density, R-6.5 Single Family High Density, R-8 Single Family High Density Small Lot, and WR-R-4-6 Whiskey Ridge, High Density Single Family into a new zone called Neighborhood Residential (NR) (see existing and proposed maps below). This change is proposed due to the State’s requirement that Middle Housing density be calculated as units per lot rather than units per acre, which reduces the differences among these zones. 

An amendment is also proposed to add the Residential Mobile Home Park (R-MHP) designation, which is currently on the City’s Zoning Map to the Comprehensive Plan Map. 

Drafts of the proposed Comprehensive Plan and Marysville Municipal Code amendments are available by following the instructions below:

  • Please visit the following webpage: Public Document Portal
    • NOTE: If a cookies error is encountered, click the "Sign Out" hyperlink. This will prompt a public login; select the "Sign in" button. Once the page refreshes, select "Planning Seach" under the "Community Development" subheading.
  • Search by the Planning Project Number CA23-011 in the “CD - Project Number” field.

Existing

Image of existing zoning map before adoption of single residential zoning, Neighborhood Residential

Proposed

Image of zoning map after adoption of single residential zoning, Neighborhood Residential

How can I provide input?

A Visual Preference Survey was conducted from mid-December 2024 to mid-February 2025 to obtain community feedback on preferred architectural design elements as well as which six of nine Middle Housing types the community would prefer to see within Marysville. 

The results of this survey are available here: Visual Preference Survey Results

Community Development staff hosted Open Houses in May and June to provide information on the State mandated Middle Housing, Accessory Dwelling Unit, and Unit Lot Subdivision regulations and to accept public feedback. 

A Planning Commission work session will be held on July 8, 2025, at 6:30 pm at 501 Delta, Avenue, 2nd Floor Council Chambers. A Public hearing on the recently adopted Interim Ordinances pertaining to Middle Housing, Accessory Dwelling Units, and Unit Lot Subdivisions will be held on Monday, July 14, 2025, at 7 pm at 501 Delta Avenue, 2nd Floor Council Chambers. Final regulations are being completed and will be considered by the Planning Commission at a Public Hearing on Tuesday, August 12, 2025, at 6:30 pm at 501 Delta, Avenue, 2nd Floor Council Chambers. We welcome you to attend these meetings and Public Hearings. 

What is the Middle Housing project schedule?

Public Outreach Public Feedback Analyzed and Standards Drafted Planning Commission work sessions and Public Hearing City Council review and adoption
Dec. 2024 - Feb. 2025 Feb. - July 2025 Feb. – Aug. 2025 Sept. or Oct. 2025

Further questions, comments or concerns?

Please email planning@marysvillewa.gov or call us at 360-363-8100 and make an appointment to meet with us.