Mill Creek staff outline state-mandated 'middle housing' code changes, timeline for updates

At the Feb. 4 Mill Creek City Council meeting, Jeff Ryan, director of community development and planning, gave a housing policy primer and described specific code changes the city must adopt to comply with state laws that expand “middle housing.” Ryan said the city must update its municipal code to meet requirements in several 2023–2024 state laws and aim to complete that work before the June compliance deadline.

Ryan told the council the objective of his presentation was to explain housing terminology, supply-and-demand basics, and how recent legislation affects local review, parking and unit types. “Housing is kind of at the center of almost all municipal problems in a lot of ways,” Ryan said. He described “middle housing” as accessory dwelling units (ADUs), duplexes, townhomes, fourplexes and sixplexes and said many of those types already exist in Mill Creek.

The presentation laid out four state authorities that drive the changes: the state Growth Management Act (1990) and three more recent bills discussed by Ryan as HB 1110, HB 1337 and HB 5258. According to Ryan, the state requirements that will affect Mill Creek include allowing at least two dwelling units per lot (or two ADUs/one ADU plus one principal unit options), administrative (staff-level) design review for middle housing in residential zones, updated parking standards near frequent transit, allowance for unit lot subdivisions, and an increase in maximum ADU size to 1,000 square feet. Ryan also said HOAs with restrictions recorded before 07/23/2023 are exempt from some requirements.

Ryan offered local market context the council said would inform decisions: 2024 data for Mill Creek showed median single-family sale prices just north of $1,000,000 and multifamily/condo median sales just under $600,000. He said 45% of the city’s housing tenure is renter-occupied (citing the comp plan) and estimated that to afford a single-family purchase in the region a household would need a roughly $264,000 annual income. Ryan emphasized those figures to frame trade-offs between zoning, density and the city’s revenue mix.

Council members asked clarifying questions. Council Member Vince pressed on the historical framing Ryan used for zoning and sought assurance the presentation did not mean the city would remove single-family zoning citywide. Mayor Pro Tem Vignell and Council Member Cavalieri asked about parking changes tied to transit; Ryan said the state’s parking exemptions apply within about a half-mile walking distance of a major transit stop. On the question of whether condos generate more property tax revenue than rental apartments, Ryan said the tax result is “probably the same,” though specifics can vary by abatements or tax programs.

Ryan described how the state changes will be implemented administratively in Mill Creek and gave a proposed schedule: present the draft code to the planning commission in March, seek council adoption in April, and submit for state (Commerce) certification in May so the city meets the June compliance deadline. He characterized the regulatory lift as modest for Mill Creek compared with other jurisdictions because some middle housing already exists and the city’s comp plan and zoning already allow several of the affected housing types.

Ryan and council members also discussed how the rules could interact with the city’s subarea planning and a future bus-rapid-transit (BRT) line. Council members noted that higher-density subarea proposals discussed previously exceed middle-housing definitions (sixplex and below) and asked whether proposed state transit-oriented rules would limit local parking minimums in those locations; Ryan said pending state bills could further change parking requirements around BRT stops.

Ryan cautioned that while code must be updated, the market still determines whether projects get built. He said many ADUs and small middle-housing projects are difficult to finance under current construction costs and that, historically, Mill Creek has allowed ADUs for years but seen few built. “Most likely, what we’re talking about for how it’s gonna manifest would be an accessory dwelling unit that would be built like a backyard flat,” Ryan said.

Ending: Ryan said staff intends to proceed on the timeline presented and bring a formal draft to the planning commission in March; he flagged possible subsequent state changes (including transit-oriented parking legislation) as items the council’s legislative committee will monitor.