WA SB5413

Counties may permit detached accessory dwelling units (DADUs) outside urban growth areas, limited to one per parcel with a maximum size of 1,296 square feet, located within 150 feet of the principal unit and sharing the same driveway

DADUs must comply with water supply requirements under RCW 19.27.097, demonstrate adequate sewage/septic capacity, meter all water withdrawals, and stay within domestic use limitations under RCW 90.44.050

Short-term rental use of a DADU requires the primary unit to be owner-occupied

Counties allowing DADUs must implement code enforcement measures including voluntary compliance with double permit fees, civil infractions of at least $1,000 for unpermitted construction, and a three-year permit ban for violators

Counties must track and annually report DADU permits to the department, update comprehensive land use plans during required reviews to account for actual and projected DADU development, with amendments permitted no more than once every five years