HB 1110 and Middle Housing in King County What It Means for Zoning Infill Lots and ADUs

For decades, much of King County’s residential land has followed a simple rule: one house on one lot. Washington’s middle housing law changes that pattern. HB 1110 does not end local zoning, but it does require many cities to allow more homes in neighborhoods that were once limited mostly to detached single-family houses.That shift matters in places like Seattle, Bellevue, Kirkland, Redmond, Renton, Shoreline, Bothell, Kent, and other King County cities where land is scarce, housing demand is high, and small infill projects can shape the next generation of neighborhoods.The law opens the door for duplexes, triplexes, fourplexes, sixplexes in some locations, cottage housing, townhomes, stacked flats, and courtyard apartments. It also works alongside recent accessory dwelling unit laws that make backyard cottages and basement apartments easier to permit in urban areas.This article is informational only and is not legal, planning, or design advice. Local codes still matter, and every lot needs its own review.Middle housing rules will shape familiar neighborhood blocks, not just large development sites.What HB 1110 changes in residential zoningHB 1110 is Washington’s middle housing law...