Alameda County, CA Fence Regulations: Retaining Walls (2026)
Key Facts
- No-permit height
- Up to 4 feet
- Tire walls
- Prohibited countywide
- Wood walls
- Barred near property lines
- Sections
- County Code §§ 15.08.060, 15.08.250
Summary
Unincorporated Alameda County exempts retaining walls under 4 feet from permitting, but taller walls need a permit, and the county bans tire retaining walls outright.
4. Retaining walls that are not over 4 feet (1219 min) 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.
5. Water tanks supported directly on grade if the capacity is not greater than 5,000 gallons (18 925 L) and the ratio of height to diameter or width does not exceed 2:1.
6. Raised decks, platforms, ramps, sidewalks and driveways accessory to Group R-3 and U occupancies not more than 30 inches (762 mm) above adjacent grade, and not over any basement or story below and are not part of an accessible route.
7. Painting, papering, tiling, carpeting, cabinets, counter tops and similar finish work.
8. Temporary motion picture, television and theater stages sets and scenery.
9. Prefabricated swimming pools accessory to a Group R-3 occupancy that are less than 24 inches (610 mm) deep, are not greater than 5,000 gallons (18 925 L) and are installed entirely above ground.
10. Shade cloth structures constructed for nursery or agricultural purposes, not including service systems.
11. Swings and other playground equipment accessory to detached one- and two-family dwellings.
12. Window awnings in Group R-3 and U occupancies, supported by an exterior wall that do not project more than 54 inches (1372 mm) from the exterior wall and do not require additional support.
Full Breakdown
Under Alameda County Code § 15.08.060, retaining walls up to 4 feet high, measured from the bottom of the footing to the top, don't need a building permit, unless the wall supports a surcharge or holds back hazardous liquids, in which case a permit is required regardless of height. Section 15.08.250 adds two county-specific standards for walls that do need engineering review: retaining walls built of tires are prohibited outright, and wood may not be used for a retaining wall at or near a property line. These rules apply only in unincorporated areas such as Castro Valley and San Lorenzo, not inside any of the county's fourteen incorporated cities.
Violations & Fines
Building a retaining wall over 4 feet without a permit, or constructing one from tires, violates county code and can trigger a stop-work order and mandatory removal or retroactive permitting.
Frequently Asked Questions
How tall can a retaining wall be without a permit in Alameda County?
Can I build a retaining wall out of old tires?
Sources & Official References
Other rules in Alameda County
California rules heatmap·Compare Alameda County to another location·View the California fence regulations overview
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