Auburn, WA Building Setbacks & Zoning: Lot Coverage Limits (2026)

Lot coverage in Auburn is the percentage of a site covered by principal and accessory buildings and is regulated in the bulk standards tables of ACC Title 18. In common R-5 zones the maximum lot coverage is around 35 to 40 percent, with smaller-lot R-7 and R-10 zones allowing up to 45 to 55 percent coverage. Decks under a specified height, paved walkways, unroofed patios, and pools are generally excluded from coverage, though they may count toward separate impervious surface limits used for stormwater review. Accessory dwelling units and detached garages are counted in lot coverage calculations. Critical areas, shoreline buffers along the Green River and White River, and tree-retention standards under ACC Title 16 can further reduce buildable area, effectively lowering the practical coverage. The city also enforces minimum pervious landscaping requirements and front-yard landscaping in several zones. When calculating lot coverage, the full parcel area is used, including easements but not public rights-of-way. Additions that push coverage over the maximum require either a smaller footprint, a lot consolidation, or a variance heard by the hearing examiner. Detailed zone tables and site-specific guidance are available from Auburn Community Development at (253) 931-3090.