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

The unincorporated county addresses retaining walls in its Title 18 Zoning Code setback rules. Section 18.30.040(C) exempts retaining walls less than three feet in height above finished grade from the minimum setback requirements, meaning a low retaining wall may be placed without observing the zone's structure setbacks. Walls three feet or higher above grade are not exempt and must meet applicable setback standards. Building-permit requirements for retaining walls come from the California Building Code, which Merced County enforces. Under CBC Section 105.2, a retaining wall is exempt from a building permit only if it is not over 4 feet (1219 mm) in height measured from the bottom of the footing to the top of the wall, and does not support a surcharge or impound hazardous liquids. So a retaining wall over 4 feet measured from the footing, or any wall retaining a sloping surcharge or additional load, requires a permit and engineering. Note the two thresholds differ: the 3-foot zoning exemption is measured above finished grade for setback purposes, while the 4-foot building-code threshold is measured from the bottom of the footing for permitting. Property owners should confirm both the setback exemption and permit requirement with Merced County Planning and Building & Safety.