Mountlake Terrace Council adopts middle‑housing code amendments to comply with state law

The Mountlake Terrace City Council voted unanimously Wednesday to adopt a package of nine zoning ordinances that rewrite large portions of the city’s residential code to implement state middle‑housing requirements and the city’s recent comprehensive plan updates.

City and consultant staff told the council the amendments are intended to expand housing types, regulate scale and design, and offer incentives for public benefits such as affordable units and tree retention. "This is our third review of code requirements to our code language to meet legislative requirements for middle housing," said Christie, Community Economic Development Director. Heidi Oian, the consultant, said chapter 19.3 (residential districts) is the most consequential: "That's the place where all of the density is allowed to change."

The ordinance package includes a new chapter (19.3) with dimensional standards and bonuses, a new residential design chapter (19.32) with objective design criteria, consolidated definitions (19.15), a residential affordability incentives chapter (3.96) that implements the state middle‑housing bonus, updates to the ADU standards to comply with state ADU rules, and reorganized parking and EV charging requirements.

Under the adopted affordability bonus rules summarized by staff, projects using the bonus must record a 50‑year covenant or deed restriction and provide affordable units substantially similar to market units. The draft also allows increased floor area ratio and lot coverage for projects that provide public benefits such as on‑site tree retention, new mid‑block connections, shared driveways, sustainability certification, or improved parking courts. "It sets a 50 year term, requires a covenant or deed restriction, requires affordable units have to be substantially similar to the market rate units," Oian said.

The council heard questions about neighborhood compatibility, capacity and the limits of local authority under state law. Council member Woodard asked which chapter will have the greatest effect; staff and the consultant pointed to chapter 19.3. Council members also discussed accessory dwelling units (ADUs): staff said the code will allow up to two ADUs per lot (subject to building code minimums of 200 square feet and a 1,000 square foot maximum), allow garage conversions, and will not require additional parking for ADUs in line with state law. "We can no longer require owner occupancy of the primary residence," the consultant said, noting several ownership and subdivision mechanisms (short plats or condominium conversion) exist for ownership changes.

Council members asked about priorities and implementation. The city manager and staff said the ordinances implement decisions made during the comprehensive plan update and represent the tiering approach adopted last year. Several council members expressed support for the package as a tool to expand housing choices and long‑term affordability. Council member Murray said the package aligns with the council’s vision and the county’s housing need projections. "I think this is a great proposal," Murray said during discussion.

The council moved and seconded the ordinance package (motion by Council member Murray; second by Council member Woodard) and then voted to adopt the recommended code amendments for middle housing. The motion passed unanimously.

What the action does and next steps: The adopted amendments change residential zoning standards and incentives immediately under the city code. Staff said additional implementation and refinement will continue in the upcoming housing action plan, scheduled for July and August, where further program details and implementation priorities will be developed.

Authorities cited in the staff presentation and in the adopted text included state middle‑housing legislation (referred to as HB 1110 in the presentation), state ADU changes (referred to as HB 1337), and the Mountlake Terrace municipal code chapters cited in the presentation (for example chapters 19.3, 19.32, 19.15, 19.23, 19.35, 19.125, 19.126 and a new chapter 3.96). The city will track compliance, including required annual reporting for affordability covenants.

The council and staff plan follow‑up work in the housing action plan and will return to council for any major implementation decisions or refinements.