Santa Clara County, CA Building Setbacks & Zoning: Lot Coverage Limits (2026)

Lot coverage in the County Zoning Ordinance is calculated as the ratio of all building footprints on a lot, including accessory structures over 120 square feet, divided by gross lot area. In R1 the maximum is 40 percent, in the RR Rural Residential district 35 percent, and in the HS Hillside combining district coverage drops on a sliding scale from 25 percent on gentle slopes to 15 percent on slopes above 30 percent. Hillside parcels also face Floor Area Ratio caps, typically 0.35 to 0.45 of gross lot area for the first 20000 square feet with smaller marginal ratios above that. State law under Government Code 66323 allows a detached ADU up to 800 square feet and 16 feet tall to be approved ministerially even if it causes the parcel to exceed local coverage or FAR limits, which is a major tool for homeowners in Saratoga, Los Gatos, and Monte Sereno foothill areas. Driveways, decks under 30 inches, uncovered patios, and pools do not count toward coverage. Pergolas and covered porches do count if they have a solid roof. Exceeding coverage without a variance is a zoning violation enforced under Division B28 with stop work orders and daily fines.