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

Lot coverage in Bellevue measures the portion of the lot covered by buildings and other structures, while impervious surface adds driveways, patios, and walkways. LUC 20.20.010 sets zone-based maximums: R-1 lots generally cap coverage at 35 percent, R-4 and R-5 at 35 to 40 percent, and denser R-7.5 and R-10 at 40 to 50 percent. Total impervious surface caps are often higher (55 to 70 percent) but trigger stormwater flow-control requirements once crossed. Critical areas overlays can reduce effective coverage because buffers must remain pervious. Eaves and covered porches typically count toward building coverage. Lot-coverage calculations are done during building permit review using the surveyor-certified lot area. Additions that push coverage over the cap may need to be redesigned, shifted, or paired with removal of other impervious features. Owners planning pools, patios, or ADUs should budget coverage carefully, especially on small lots where every square foot counts. Violations discovered later (e.g., a shed added without permit) can require removal or formal after-the-fact permitting with fines.