Retaining walls over 4 feet in height (measured from bottom of footing to top) require a building permit and engineered plans in unincorporated Alameda County under the California Building Code.
Alameda County enforces the California Building Code for retaining walls. Walls retaining more than 4 feet of unbalanced fill (measured from the bottom of the footing to the top of the wall) require a building permit, engineered plans stamped by a licensed civil or structural engineer, and inspections. Walls supporting a surcharge (such as a driveway, structure, or sloping backfill) may require a permit regardless of height. In the East Bay hillside areas including Castro Valley, San Lorenzo foothills, and unincorporated Fairview and Sunol, soils investigation may be required due to expansive clays, landslide risk, and seismic considerations along the Hayward Fault. Drainage behind walls must comply with grading ordinance requirements to prevent saturation and failure. Permits are issued by the Alameda County Public Works Agency Building Inspection Division at (510) 272-6984.
Contact your local code enforcement office for specific penalty information.
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Side-by-side rule comparisons with other cities in Alameda County.
See how other cities in Alameda County handle retaining walls.
See how Sunol's retaining walls rules stack up against other locations.
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