Bill > HB1345

This bill establishes limitations on detached accessory dwelling units (ADUs), which are separate housing units on the same property as a main home, when they are located outside of designated urban growth areas. Counties that choose to allow these detached ADUs in such areas must adhere to specific regulations, including limiting each parcel to only one ADU (attached or detached), ensuring adequate water supply and groundwater mitigation, and metering water usage for each dwelling. The detached ADU's size is capped at the equivalent of an expansion to create an attached ADU, with a maximum of 1,296 square feet, excluding garages and unfinished basements. It must share the same driveway as the main home and be located within 150 feet of it, and cannot be placed on lots smaller than one acre. The bill also mandates that counties have code enforcement measures for unpermitted ADUs, including penalties and a three-year prohibition on new ADU permits for repeat offenders. Furthermore, counties must track and report ADU permits, update their comprehensive land use plans to account for ADU development and projected growth, and limit population growth targets allocated to detached ADUs, with specific percentages for rural and non-rural counties. These provisions aim to manage the development of ADUs outside urban centers while ensuring they do not exceed underlying density allowances in comprehensive plans.

Housing and Urban Affairs

https://app.leg.wa.gov/billsummary?BillNumber=1345&Year=2025&Initiative=false