This bill creates a new section in chapter 36.70A RCW and amends two city planning provisions (RCW 35.21.990 for cities and RCW 35A.21.440 for code cities) to change land use rules around adding housing in commercial and mixed-use buildings near high-capacity transit. It requires cities and code cities that plan under RCW 36.70A.040 to allow conversion or addition of housing units in ground-floor commercial or retail space inside defined "station areas" except where a site is locally designated as a "major pedestrian corridor," and it limits any city’s designation of major pedestrian corridors to no more than 10% of its mixed-use or commercial zoned area. The bill also requires an expedited process to allow deviations from street-level use standards when those standards would reduce housing unit counts. The bill limits what local governments may impose on adding housing within existing buildings: it prohibits new density caps within the existing building envelope (allowing up to 50% more density), new parking requirements specific to added units, additional permitting or design standards beyond those generally applicable, and requirements for transportation concurrency or environmental studies based solely on adding residential units in existing buildings. It also requires zoning that allows greater height and density in all commercial and mixed-use zones for developments built using mass timber products, and it clarifies that permits need not be approved if life-safety standards cannot be met. Key definitions included are "station area" (lots in an urban growth area within specified walking distances of certain rail stations or designated bus rapid transit stops), "existing building" (certificate of occupancy at least three years before the permit application), and "mass timber products" (by reference to RCW 19.27.570). Cities and code cities must adopt or amend the required ordinances and controls for commercial or mixed-use zoned buildings no later than six months after their next periodic comprehensive plan update; the amendments include preemption language that conflicts with local development regulations if the required rules are not timely adopted. The text provided does not define "major pedestrian corridor" and relies on cross-referenced statutes (e.g., RCW 36.70A.130, RCW 35.58.2795, chapter 43.21C RCW) for implementation details, so the full scope and interaction of these changes with existing state and local law is not fully clear from these extracts alone.

If enacted, cities would have to make it easier to add housing inside existing commercial or mixed-use buildings near high-capacity transit stations by allowing ground-floor housing in most station-area commercial spaces, limiting how much area can be carved out as protected "major pedestrian corridors," and barring many common local barriers like new parking mandates, extra permits or special design rules for those added units. Owners and developers of qualifying existing buildings could likely add up to 50% more units inside the current building envelope with fewer local hurdles, and projects using mass timber could get zoning allowances for extra height and density, though buildings still must meet life-safety rules. The groups most affected are city planning and permitting departments, which must revise ordinances within six months after their next periodic comprehensive plan update or face state preemption, and building owners/developers, who would gain lower regulatory costs and faster options to add housing. Cities will need staff time to change codes and may lose some local control over street-level uses and parking/transport impacts; transit agencies matter only insofar as their plans and environmental findings determine which stops qualify. The bill leaves open key details—especially what counts as a "major pedestrian corridor" and how the timing ties to each city's plan update—so some implementation questions remain.