Washington Statewide ADU Preemption Under HB 1337

Effective 2024, RCW 36.70A.681 requires Growth Management Act jurisdictions to allow at least two accessory dwelling units (one attached and one detached, or two attached/detached) on residential lots within urban growth areas. The law caps minimum lot size, prohibits owner-occupancy requirements, bans off-street parking mandates within a half-mile of major transit, and prohibits design standards stricter than those for principal dwellings. Local ADU ordinances inconsistent with these state minimums are unenforceable.

Local rules conflicting with RCW 36.70A.681 are preempted and unenforceable; aggrieved property owners may seek judicial relief.