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

Retaining walls in unincorporated Riverside County are regulated primarily through building-permit rules administered by County Building and Safety. Under the California Building Code adopted by the County, a retaining wall is exempt from a building permit only when it is 'not over 4 feet in height measured from the bottom of the footing to the top of the wall, unless supporting a surcharge or impounding Class I, II or IIIA liquids.' So a retaining wall taller than 4 feet, or any wall holding back a slope load or liquids, requires a permit. The County's own exemption handout treats masonry/block walls more strictly, exempting only 'Block walls not over 3' in height from grade (measured 4 ft from the bottom of the footing to top of the wall).' For taller or load-bearing walls, the County generally requires an engineered design - block walls over 6 feet typically need engineering submitted for approval. Riverside County Zoning Ordinance No. 348 does not set a separate retaining-wall height cap, but where a retaining wall sits in a required yard, the yard-encroachment limits of Section 18.19 and any specific-plan standards still apply. Because soil and slope conditions vary across the county's hillside and desert terrain, engineering review protects against failure.