Showing ordinances that apply to Port Costa, CA
Port Costa is an unincorporated community (population 190) in Contra Costa County, California. Because Port Costa is not an incorporated city, it does not have its own municipal code. Instead, Contra Costa County ordinances apply directly to properties here. The retaining walls rules below are the ones that govern your area.
Retaining walls over 3 to 4 feet of retained earth require a building permit and engineered design in unincorporated Contra Costa County. Walls with surcharge (buildings, driveways, slopes above) typically require a permit at any height. Setbacks and drainage must meet county grading standards.
Contra Costa County's building code (based on the California Building Code) exempts from permit requirements most retaining walls of 4 feet or less measured from the bottom of the footing to the top of the wall, provided there is no surcharge (no building, driveway, pool, or significant slope above that loads the wall). Walls over 4 feet or any wall with surcharge require a permit and typically an engineered design stamped by a licensed civil or structural engineer. In the hilly portions of Contra Costa — Alamo, Blackhawk, Kensington, El Sobrante, Orinda fringe, and the San Ramon-Danville foothills — expansive clay soils and landslide risk often push grading-permit thresholds lower and drive engineering requirements. Drainage must direct water away from neighbors and not create erosion onto adjacent parcels (grading ordinance). Walls in mapped landslide, fault, or Alquist-Priolo zones receive additional scrutiny. Adding a fence on top of a retaining wall is permitted, but combined height (retained earth + fence) is calculated for fence-permit thresholds and for sight-distance rules. Unpermitted walls that fail can create personal-injury liability and insurance issues; the county can require removal or retrofit of non-compliant walls.
Contact your local code enforcement office for specific penalty information.
See how Port Costa's retaining walls rules stack up against other locations.
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