Westminster, CA Fence Regulations: Retaining Walls (2026)

Retaining walls in the incorporated City of Westminster are subject to both the city's wall-height measurement rules and California's statewide permit thresholds. Westminster Municipal Code Section 17.300.030 governs walls used as fences and sets out how height is measured: along an interior property line, from the higher natural or established grade of the two abutting properties, and from the abutting right-of-way grade if the wall is within five feet of a public right-of-way. Because a retaining wall by definition holds back a grade difference, that measurement rule directly affects how much wall is counted toward the zoning height limit. The building-permit question is governed by the California Building Code: under CBC Section 105.2, masonry or concrete walls not over four feet in height measured from the bottom of the footing to the top of the wall are exempt from a building permit, while taller walls — or any wall retaining a surcharge such as a slope or driveway load — require a permit and engineered design. Westminster does not appear to publish a city-specific retaining-wall height cap separate from these standards, so property owners should treat four feet (from footing) as the state permit threshold and confirm zoning compliance and any required engineering with the city's Building and Planning Divisions before construction.