Bellevue permits accessory dwelling units under Land Use Code (LUC) 20.20.120, substantially amended by Ordinance 6746 (2023 ADU Reform LUCA). Washington HB 1337 (RCW 36.70A.681) requires Bellevue to allow up to two ADUs per lot in urban growth areas, and the city's middle-housing LUCA is being adopted to comply by the June 30, 2025 statewide deadline.
LUC 20.20.120 governs ADUs in Bellevue. The 2023 ADU Reform (Ordinance 6746) eliminated registration and noticing requirements, removed design controls beyond standard single-family standards, increased maximum size to 1,200 sq ft or 40 percent of the structure (whichever is larger), allowed condominium-style separate sale, and removed owner-occupancy. Building permits are still required and are filed through MyBuildingPermit.com, the regional permitting portal Bellevue uses. Attached ADUs must be located within or attached to the primary structure and follow the same height and setback rules. Washington HB 1337 (RCW 36.70A.681 through .696) requires Bellevue, as a city subject to the Growth Management Act, to permit at least two ADUs per lot in urban growth areas, with implementation in Bellevue handled through the Middle Housing LUCA. A pre-occupancy inspection by a land use planner is required before final occupancy. The 2021 I-Codes (WA State Building Code, WAC 51-50) apply effective March 15, 2024.
Constructing an ADU without permits is a Land Use Code violation under LUC 20.40 (Enforcement) and Bellevue City Code Title 1.18. Civil penalties run up to $500 per day per violation. The city may issue stop-work orders, require removal, and assess double permit fees on retroactive applications. Occupancy without final inspection sign-off is a separate violation.
Bellevue, WA
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Bellevue, WA
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Bellevue, WA
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Bellevue, WA
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Side-by-side rule comparisons with other cities in King County.
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