Retaining Walls: Altadena vs South Gate
How do retaining walls rules compare between Altadena, CA and South Gate, CA?
Altadena and South Gate have similar restriction levels.
Altadena, CA
Los Angeles County
Retaining walls in unincorporated LA County under 4 ft from footing to top are exempt from building permits unless supporting a surcharge. Walls in required yards cannot exceed 6 ft. In coastal areas, retaining walls must be terraced and landscaped with native species before the rainy season (Oct 15-Apr 15).
View full Altadena rules →South Gate, CA
Los Angeles County
Retaining walls in South Gate are regulated under Chapter 9.02 (Building Code), which adopts the California Building Code (Title 24). Walls retaining more than 4 feet of fill, measured from the bottom of footing to the top of wall, require a building permit and engineered design. Zoning setbacks and combined fence-on-wall height limits in Chapter 11.25 also apply.
View full South Gate rules →Key Facts Comparison
| Fact | Altadena | South Gate |
|---|---|---|
| Permit Exempt | Under 4 ft height | - |
| Yard Maximum | 6 ft in required setbacks | - |
| Coastal | Must terrace and landscape | - |
| Engineering | Soils report for taller walls | Licensed CA civil/structural engineer for permitted walls |
| Permit threshold | - | Retains >4 ft fill (bottom of footing to top of wall) |
| Code authority | - | South Gate MC Ch. 9.02 adopts CA Building Code (Title 24) |
| Zoning treatment | - | Combined wall + fence height counted as single structure under Ch. 11.25 |
Highlighted rows indicate differences between cities.
Altadena FAQ
Do I need a permit for a retaining wall in LA County?
Only if the wall exceeds 4 feet from footing to top. Walls over 4 feet need a building permit and engineered plans from a licensed engineer. Contact Building & Safety at (626) 458-3171.
Can I build multiple short walls instead of one tall one?
Tiered walls with less than the height of the lower wall between them are measured as a single wall for permit purposes. This prevents circumventing the 4-foot permit threshold.
What if my retaining wall is failing?
A failing retaining wall is a safety hazard. Contact Building & Safety at (626) 458-3171 immediately. You may need emergency repairs and a geotechnical evaluation. You are liable for damage to adjacent properties.
South Gate FAQ
Do I need a permit for a retaining wall?
Yes if the wall retains more than 4 feet of fill (measured from the bottom of the footing to the top of the wall) or if it supports a surcharge such as a driveway, pool, or upslope soil. South Gate adopts the California Building Code through Chapter 9.02.
Can I put a 6-foot fence on top of my retaining wall?
Possibly, but the combined height of the wall and the fence is treated as a single structure for South Gate's Chapter 11.25 height limit. A 4-ft retaining wall plus a 6-ft fence (10 ft total) would exceed the standard 6-ft side-yard limit and require a variance.
What engineering is required?
Walls over 4 feet need a stamped design from a California-licensed civil or structural engineer. The plans must address soil bearing, drainage, weep holes, and any surcharge load before South Gate Building & Safety will issue the permit.
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