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

Lot coverage and minimum lot dimensions in unincorporated Sonoma County are set district-by-district in Chapter 26 of the Zoning Code. For the R1 Low Density Residential district, Section 26-20-030 establishes a maximum lot coverage of forty percent (40%) - that is, buildings may cover up to 40% of the total lot area - and the section notes that lot coverage may be waived by the planning director for swimming pools. The same R1 standards set a minimum lot size of six thousand (6,000) square feet and a minimum average lot width of sixty feet (60'); residential density in R1 is between one and six units per acre as shown in the general plan.

Accessory buildings placed in required yards on the rear half of the lot may not occupy more than thirty percent (30%) of the width of the rear yard (swimming pools are excepted). These figures are specific to R1; other zoning districts - higher-density residential such as R2 and R3, rural residential, agricultural and commercial zones - have their own coverage percentages, minimum lot sizes and density ranges. For comparison, the R3 High Density Residential district allows up to 60% lot coverage. Because coverage limits, minimum lot size and density all depend on your parcel's zoning district and general-plan designation, confirm the numbers for your specific zone with Permit Sonoma before planning an addition or new structure.