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

Glenn County Code Section 15.37.110, in the R-1 Single Family Residential Zone chapter, sets the coverage ceiling in a single sentence: 'the maximum lot coverage shall be 40% of the total lot area,' with a reduced 30 percent ceiling for areas where slopes are greater than 30 percent. The lower slope-based figure reflects the county's grading and erosion concerns on hillside parcels within the R-1 district, forcing a smaller building footprint where steep grades increase runoff and slope-stability risk. This coverage figure was added by Ordinance 1200 Section 3 in 2008, layered onto the R-1 zone's earlier 2006 Ordinance 1183 framework that set the zone's yard and height standards.

The same 40 percent standard, again reduced to 30 percent on steep slopes, is repeated in the neighboring R-M Multiple Residential zone at Section 15.38.120 and in the CC Community Commercial District at Section 15.40.080, so the ratio is the county's general residential and commercial coverage benchmark rather than a one-off R-1 number. Lot coverage is calculated against the parcel's total lot area and includes the building footprint together with attached and accessory structures counted toward that footprint; the Planning and Building Department checks this figure as part of building permit and site plan review under Chapter 15.13.