Retaining wall permit checklist — Ontario, California
Assembled from Ontario’s own published permit rules. Every line below is quoted from a city document and linked to it. Nothing here is generated, estimated, or inferred from another jurisdiction.
Do you need a permit?
Ontario requires a permit for a retaining wall.
Ontario amends the state threshold sharply downward: a permit is required for any retaining wall over 2 feet in height measured from the bottom of the footing to the top of the wall -- half the 4-foot threshold in CBC/CRC 105.2. This is the single most important local deviation to know in Ontario, because a wall that would be permit-exempt in Huntington Beach or Glendale requires a permit here.
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Sources
- retaining wall — permit rules ↗verified August 2026
Other permits Ontario publishes rules for
Listed because the city publishes a separate rule for each type — not because this project necessarily triggers one. Whether it does depends on your scope of work.
- Fence permit checklist
- Shed permit checklist
- Water heater permit checklist
- Re-roof permit checklist
- Electrical work permit checklist
- General building work permit checklist
BuildSpec is a reference, not the authority having jurisdiction. Confirm requirements with Ontario before you build.