Tiny home rules in Seattle, WA — covering tiny houses on wheels (THOWs), park model RVs, and tiny home on foundation builds — determine where they are legal and how they get permitted.
Seattle allows tiny houses on permanent foundations as Detached Accessory Dwelling Units (DADUs) under SMC 23.42.022 and SMC 23.44.041, subject to the same code as any DADU. Tiny houses on wheels (THOWs) are treated as recreational vehicles and may not be used as residences in city residential zones. Sanctioned tiny house villages exist only as transitional encampments under SMC 23.42.054.
Under SMC 23.42.022 and SMC 23.44.041, a tiny house in Seattle qualifies as a DADU only if built on a permanent foundation and meeting Seattle Residential, Building, Mechanical, Electrical, and Energy codes. DADUs may be up to 1,000 sq ft and up to 32 ft in height in Neighborhood Residential and RSL zones, with up to two ADUs allowed per lot under HB 1337 compliance. Tiny houses on wheels (THOWs) are classified as recreational vehicles and prohibited as full-time dwellings on lots inside Seattle city limits; they cannot be parked and inhabited in residential zones the way an ADU can. Sanctioned tiny house villages operate as transitional encampments under SMC 23.42.054, which allows encampments on property owned or controlled by a religious organization in any zone without a separate land use permit, and on non-religious sites with a Type I Master Use Permit. Permit costs for a DADU tiny house typically run $2,500-$4,000 through the SDCI portal, with an 8-12 week review timeline.
Living in a tiny house on wheels in a Seattle residential zone is treated as illegal occupancy of an RV/vehicle and is subject to removal and SDCI notice of violation. Unpermitted tiny-house DADU construction triggers a stop-work order and penalties. Transitional encampments operating outside SMC 23.42.054 standards are subject to permit revocation and shutdown.
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Side-by-side rule comparisons with other cities in King County.
See how other cities in King County handle tiny homes.
See how Seattle's tiny homes rules stack up against other locations.
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