Retaining Walls: Daly City vs San Mateo
How do retaining walls rules compare between Daly City, CA and San Mateo, CA?
San Mateo has fewer restrictions than Daly City.
Daly City, CA
San Mateo County
Retaining walls in Daly City are regulated under Title 12 (Buildings and Construction) of the Municipal Code, which adopts the California Building Code. Under California Building Code Section 105.2, retaining walls over 4 feet measured from the bottom of the footing to the top of the wall, or any wall supporting a surcharge, require a building permit.
View full Daly City rules →San Mateo, CA
San Mateo County
Retaining walls in San Mateo under 4 feet in height (measured from bottom of footing) are generally exempt from building permits under the California Building Code. Walls over 4 feet require a building permit and may need engineered plans. San Mateo's hillside terrain makes retaining walls common.
View full San Mateo rules →Key Facts Comparison
| Fact | Daly City | San Mateo |
|---|---|---|
| Permit threshold | Over 4 feet (footing to top) or any height with surcharge | - |
| Governing code | California Building Code via Daly City MC Title 12 | - |
| Engineering required | Stamped plans for engineered walls | - |
| Reviewing department | Daly City Building Division | - |
| Geo-hazard considerations | San Andreas Fault, Mussel Rock landslide area | - |
| Permit Exempt | - | Under 4 ft, no surcharge |
| Permit Required | - | Over 4 ft or with surcharge |
| Engineering | - | Licensed engineer for 4+ ft |
| Drainage | - | Critical — especially hillside |
| Building Division | - | 650-522-7200 |
Highlighted rows indicate differences between cities.
Daly City FAQ
Do I need a permit for a 3-foot landscape wall in Daly City?
A retaining wall 4 feet or less (measured from the bottom of the footing to the top of the wall) without a surcharge is generally exempt from a building permit under California Building Code 105.2, but it must still meet zoning setbacks. Confirm with the Building Division at 650-991-8061.
Are there extra rules on hillside lots in Westlake or Serramonte?
Yes - parcels in hillside, fault-zone, or known landslide areas (such as parts of Westline Drive near Mussel Rock) typically require a geotechnical report and stamped engineered plans even for walls that would otherwise be exempt, due to slope stability and seismic concerns.
San Mateo FAQ
Do I need a permit for a retaining wall in San Mateo?
Walls under 4 feet not retaining a slope or surcharge are generally exempt. Walls over 4 feet or with surcharges require a building permit and engineering.
Why is drainage important for retaining walls?
San Mateo's hillside terrain creates significant water pressure behind walls. Proper drainage with weep holes or French drains prevents hydrostatic failure.
Can a retaining wall also serve as a fence?
Yes, but the combined structure must meet both retaining wall and fence regulations. The total height may trigger different permit requirements.
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