Auburn, WA Accessory Structures: Garage Conversions (2026)

Converting a garage to habitable space in Auburn requires a change-of-use building permit from Community Development under ACC 15.36. The converted space must meet current 2021 IRC habitability standards: minimum ceiling height 7 feet, egress window in any sleeping room (minimum 5.7 sq ft openable, 20 inch width, 24 inch height, 44 inch sill height), smoke and CO alarms, insulation to current energy code (WSEC 2021), heating capable of maintaining 68 degrees F, and proper electrical and plumbing permits if added. If the converted space is independent with its own kitchen, bath, and entrance, it is classified as an ADU and must follow ACC 18.31.120 (see ADU rules). Washington HB 1337 generally eliminates the requirement to replace lost garage parking within one-half mile of a major transit stop. Beyond that radius, Auburn may still require one replacement space. Converted garages that become bedrooms or family rooms within the primary dwelling do not create ADUs and do not face parking replacement issues. Lot coverage, setbacks, and design standards still apply to any exterior modifications such as new window openings, infill walls, or removed garage doors.