Washington Accessory Apartments Statute




Accessory Dwelling Units

Washington state law requires all counties planning under the Growth Management Act, counties with populations over 125,000, and cities with populations over 20,000 to adopt zoning standards that conform to the state’s model accessory dwelling unit (ADU) ordinance. The state’s model ordinance addresses the relationship of ADUs to other applicable codes, water supply and sewage, lot coverage and setbacks, ADU type, the number of permissible ADUs per residence, owner occupancy, ADUs in new and existing dwellings, ADU size, ADU appearance, ADU entrances, parking requirements, and reasonable accommodations for disabilities.