Glenn County, CA Fence Regulations: Retaining Walls (2026)

Retaining walls in unincorporated Glenn County are regulated chiefly through the California Building Code that the county adopts and enforces. Under the 2022 California Building Code Section 105.2, a retaining wall that is not over 4 feet in height, measured from the bottom of the footing to the top of the wall, is exempt from a building permit, unless the wall supports a surcharge (such as a slope, driveway, or structure above it) or impounds flammable liquids. A retaining wall over 4 feet, or any wall supporting a surcharge regardless of height, requires a building permit through the Glenn County permit counter and typically engineered plans. Where a retaining wall is combined with a fence on top, the building-permit analysis considers the wall and fence together, and the fence portion still must meet Title 15 zoning standards (including the sight-distance rule near intersections). Glenn County's Title 15 also addresses how height is measured at grade changes, and on parcels with slopes the county may require drainage and structural review. Always confirm the currently adopted building code edition and any local amendments with Glenn County Planning & Community Development Services before construction, because retaining structures carry safety and liability exposure.