Retaining Walls: Mountain View vs Palo Alto
How do retaining walls rules compare between Mountain View, CA and Palo Alto, CA?
Mountain View and Palo Alto have similar restriction levels.
Mountain View, CA
Santa Clara County
Retaining walls over 4 feet in height (measured from bottom of footing) require a building permit and engineering in Mountain View, with additional scrutiny for walls supporting surcharge loads.
View full Mountain View rules →Palo Alto, CA
Santa Clara County
Palo Alto requires a building permit for any retaining wall over 3 feet tall or supporting a surcharge, with engineered drawings required above 4 feet under PAMC Title 16.
View full Palo Alto rules →Key Facts Comparison
| Fact | Mountain View | Palo Alto |
|---|---|---|
| Permit threshold | Over 4 feet | - |
| Surcharge walls | Permit any height | - |
| Engineering | Typically required | - |
| Combined fence wall | Counted together | - |
| Code reference | CBC 105.2 | - |
| Under 3 feet | - | No permit (no surcharge) |
| 3 to 4 feet | - | Permit required |
| Over 4 feet | - | Engineered design |
| Hillside zones | - | Geotech review |
| Drainage | - | Required |
Highlighted rows indicate differences between cities.
Mountain View FAQ
Is a 3 foot garden wall permitted?
A freestanding wall under 4 feet without a slope load is typically exempt from permits but must meet zoning setbacks.
What about a 3 foot wall with a 6 foot fence on top?
A combined system of 9 feet will be reviewed together and likely requires both a permit and fence exception.
Palo Alto FAQ
Does a planter box count as a retaining wall?
Only if it holds back more than 3 feet of retained earth; freestanding planters do not.
Can I stack landscape blocks?
Dry-stack walls up to 3 feet without surcharge are allowed without a permit.
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