Manteca, CA Fence Regulations: Retaining Walls (2026)

California Residential Code R105.2 and California Building Code 105.2 exempt retaining walls up to 4 feet in exposed height (measured from the bottom of the footing to the top of the wall) from permit requirements, so long as no surcharge load is applied. San Joaquin County Building Services enforces this through Development Title §9-1200: any retaining wall over 4 feet, or any wall of any height supporting a driveway, structure, swimming pool, or sloping ground above the wall, requires a building permit and engineered plans stamped by a California-licensed civil or structural engineer. Drainage behind the wall (gravel backfill with perforated pipe) is required to prevent hydrostatic pressure failure. Setbacks follow the zoning district fence standards, typically 3 to 5 feet from side and rear property lines for walls over 6 feet. Properties along the San Joaquin Delta, Calaveras River, Mokelumne River, and former peat-soil ag lands (Terminous, Thornton, Holt area) require geotechnical investigation for any retaining wall over 3 feet due to liquefaction potential under CBC 1803. Walls over 6 feet combined with fence heights require a separate fence permit. Engineered wall design must meet CBC 1807.1 for lateral soil pressures.