Retaining Walls: Carson vs Santa Monica
How do retaining walls rules compare between Carson, CA and Santa Monica, CA?
Carson and Santa Monica have similar restriction levels.
Carson, CA
Los Angeles County
Carson follows California Building Code (Title 24 CCR Part 2) adopted by reference in Carson's Building Code chapter. A building permit is required for any retaining wall over 4 feet measured from the bottom of the footing to the top of the wall, or for any retaining wall supporting a surcharge (sloped backfill, driveway load, or impounded fluids). Engineered plans by a licensed civil/structural engineer are required at permit threshold.
View full Carson rules →Santa Monica, CA
Los Angeles County
Retaining walls in Santa Monica over 4 ft in Seismic Design Category D, E, or F cannot be constructed of wood. Fence height on top of retaining walls is measured from lowest grade within 3-ft radius. Engineering required for significant walls.
View full Santa Monica rules →Key Facts Comparison
| Fact | Carson | Santa Monica |
|---|---|---|
| Permit threshold | Over 4 ft (bottom of footing to top) OR any surcharge | - |
| Governing code | Carson Building Code adopting CBC/CRC (Title 24 CCR) | - |
| Engineering | Stamped plans required at/above permit threshold | Required for significant walls |
| Height measurement (combined w/ fence) | From higher adjacent grade | - |
| Inspection | Footing, reinforcement, drainage, final | - |
| Wood Prohibited | - | SDC D/E/F over 4 ft |
| Height Measurement | - | From lowest grade within 3 ft |
| Seismic | - | AWPA U1 treatment required |
Highlighted rows indicate differences between cities.
Carson FAQ
Do I need a permit for a 3-foot landscape retaining wall in my Carson backyard?
Generally no, provided it's under 4 ft from footing bottom to top AND not supporting a surcharge (sloped soil pushing on it, driveway, or structure). If any of those apply, you need a permit.
Can I stack a fence on top of a retaining wall to get more privacy?
Yes but combined height is measured from the higher adjacent grade under Carson's zoning code, so the fence above counts toward the 6-ft (or 8-ft where allowed) overall height limit.
Who designs the wall?
Walls over 4 ft or with surcharge require engineered plans by a California-licensed civil or structural engineer; Carson Building & Safety will not accept owner-drawn plans for these walls.
Santa Monica FAQ
Do I need a permit for a retaining wall?
In Santa Monica, walls over 4 feet typically require a building permit and engineered plans. Shorter walls may be exempt.
How close to the property line can I build a retaining wall?
Setback requirements vary. Check Santa Monica zoning code for specific distances from property lines.
Compare other topics
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