Establishing limitations on detached accessory dwelling units outside urban growth areas.

SB 5470 establishes rules for detached accessory dwelling units (secondary housing units) on single-family properties outside urban growth areas in Washington. It limits each parcel to one such unit, caps size at 1,296 square feet (excluding garages), requires water/sewer capacity documentation, and mandates units be within 150 feet of the main home. Counties must annually track permits and short-term rentals, update land use plans to account for these units, and prohibit short-term rentals unless the main home is owner-occupied. The bill applies to rural and suburban areas where counties currently allow such units.