Retaining Walls: Fontana vs Ontario
How do retaining walls rules compare between Fontana, CA and Ontario, CA?
Fontana has fewer restrictions than Ontario.
Fontana, CA
San Bernardino County
Retaining walls in Fontana require a building permit once they retain more than 4 feet of soil measured from the bottom of the footing, or at any height if they support a surcharge. Structural plans, drainage design, and geotechnical review are often required.
View full Fontana rules →Ontario, CA
San Bernardino County
Ontario requires a permit for any retaining wall over 4 feet (footing to top) or carrying a surcharge such as a slope or driveway. Engineered plans by a licensed California civil or structural engineer are required.
View full Ontario rules →Key Facts Comparison
| Fact | Fontana | Ontario |
|---|---|---|
| Permit Threshold | Retains over 4 ft or with surcharge | - |
| Plans | Stamped structural calcs | Licensed engineer required |
| Geotech | Often required over 4 ft | - |
| Drainage | Weep holes or French drain required | Cannot flow to neighbor |
| Combined Height | Counts toward fence height | - |
| No Permit | - | Up to 4 feet unsurcharged |
| Permit Required | - | Over 4 feet or surcharged |
| Measurement | - | Bottom of footing to top |
Highlighted rows indicate differences between cities.
Fontana FAQ
Do I need a permit for a 3-foot rockery?
If it retains 3 feet of soil with no surcharge, likely no structural permit, but still follow setback and drainage rules.
My wall failed after rain. What now?
Document the failure and contact Building and Safety. Repair plans may need engineering review, especially if there is slope above.
Ontario FAQ
Does a 3-foot retaining wall in Ontario need a permit?
Usually no if it is unsurcharged. If a slope, driveway, or pool loads the top of the wall, it is surcharged and does need a permit.
Who is liable if the wall fails?
The property owner. Using an engineer and permit creates a defensible record. Unpermitted walls expose you to liability for damage downhill and next door.
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