Mountlake Terrace planning commissioners review middle-housing rules, ADU limits under new state law

Mountlake Terrace planning commissioners spent their March 10 meeting focused on draft development-code changes and the city’s housing action plan aimed at implementing recent Washington state middle-housing and accessory-dwelling-unit (ADU) laws.

The meeting, convened by Chair Bautista, featured consultants from Methune and Echo Northwest presenting code options and asking the commission for direction on what housing types to allow, how to measure and incentivize density, and how to protect trees and neighborhood character while meeting state requirements such as those in House Bill 1110 and House Bill 1337. Commissioners did not take any formal votes.

Why it matters: the state law requires jurisdictions to allow more middle-housing types and to permit ADUs under new minimums and it sets deadlines that the city must meet. The commission’s decisions will shape how new housing can fit into existing Mountlake Terrace neighborhoods, affecting site layout, parking, tree canopy and the visual scale of infill development.

Presenters told commissioners the city already rezoned residential neighborhoods into four new R zones under the comprehensive plan and now must adopt matching development standards. Consultant Heidi Oian of Methune said the team will both draft code and run “test fits” to check how different standards play out on typical Mountlake Terrace lots. “I am Heidi Oian. I’m a partner at Methune. I practice both architecture…