Retaining Walls: Daly City vs Redwood City
How do retaining walls rules compare between Daly City, CA and Redwood City, CA?
Daly City and Redwood City have similar restriction levels.
Daly City, CA
San Mateo County
Retaining walls in Daly City over 48 inches tall - or shorter walls supporting a surcharge or excavated uphill slope - require a building permit and design by a licensed professional engineer. Walls under 48 inches holding only landscaping backfill may be wood.
View full Daly City rules →Redwood City, CA
San Mateo County
A building permit is required for a fence built on top of a retaining wall in unincorporated San Mateo County. Under the California Building Code, retaining walls over 4 feet high (measured from the bottom of the footing) — or any wall supporting a surcharge — also require a permit.
View full Redwood City rules →Key Facts Comparison
| Fact | Daly City | Redwood City |
|---|---|---|
| Permit threshold | Over 48 in., or any height with surcharge/uphill slope | - |
| Engineering | Licensed professional engineer design + structural review | - |
| Height measurement | Bottom of footing to top of wall | - |
| Wood walls | Allowed under 48 in. for landscaping backfill only | - |
| Easement walls | Subject to removal if blocking utility access | - |
| Fence on retaining wall | - | Building permit required |
| Wall permit threshold (CBC 105.2) | - | Over 4 ft from bottom of footing |
| Surcharge walls | - | Permit required at any height |
| Abrupt grade shift | - | Max 12 ft fence/wall (Sec. 8.332.020) |
| Fence measured from | - | Lowest adjacent natural grade |
| Code authority | - | California Building Code + Ch. 8.332 |
Highlighted rows indicate differences between cities.
Daly City FAQ
Do I need a permit for a 3-foot retaining wall?
Not if it only retains landscaping backfill. But if it supports a surcharge (like a driveway or structure) or an excavated uphill slope, a building permit and engineered design are required even under 48 inches.
How is retaining wall height measured?
From the bottom of the footing to the top of the wall, per the City's Fences and Retaining Walls handout - not from finished grade like a fence.
What is the difference between a fence and a retaining wall?
Per the City handout, a fence supports its own weight, while a retaining wall supports the horizontal force of adjoining soil, structures, or hillsides.
Redwood City FAQ
Do I need a permit for a retaining wall in unincorporated San Mateo County?
Under California Building Code Section 105.2, a permit is required for retaining walls over 4 feet measured from the bottom of the footing, or any wall supporting a surcharge regardless of height. A fence built on top of any retaining wall also requires a building permit.
Can I add a fence on top of my retaining wall?
Yes, but it requires a building permit, and the combined fence height is measured from the lowest adjacent natural grade, so it may exceed the 4-foot or 6-foot limits and need a Fence Height Exception. Section 8.332.020 caps walls at abrupt grade shifts at 12 feet.
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