Washington Statewide ADU Preemption Under HB 1337

Accessory dwelling units — Limitations on local regulation. (1) In addition to ordinances, development regulations, and other official controls adopted or amended to comply with this section and RCW 36.70A.680 , a city or county must comply with all of the following policies: (a) The city or county may not assess impact fees on the construction of accessory dwelling units that are greater than 50 percent of the impact fees that would be imposed on the principal unit; (b) The city or county may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy the accessory dwelling unit or another housing unit on the same lot; (c) The city or county must allow at least two accessory dwelling units on all lots that are located in all zoning districts within an urban growth area that allow for single-family homes in the following configurations: (i) One attached accessory dwelling unit and one detached accessory dwelling unit; (ii) Two attached accessory dwelling units; or (iii) Two detached accessory dwelling units, which may be comprised of either one or two detached structures; (d) The city or county must permit accessory dwelling units in structures detached from the principal unit; (e) The city or county must allow an accessory dwelling unit on any lot that meets the minimum lot size required for the principal unit;