Ontario, CA Fence Regulations: Retaining Walls (2026)
Key Facts
- Retaining wall max near ROW
- 3 ft
- Free wall max near ROW
- 6 ft
- Overall max near ROW
- 9 ft
- Tiering required
- When over 3 ft of retention adjacent to ROW
- Code Section
- Development Code 6.02.020.C.5-C.6
Summary
Where grade differs between properties or a property and the public right-of-way, Ontario allows a wall or fence combined with a retaining wall above the normal height limit, but a retaining wall adjacent to the public right-of-way is capped at 3 feet, with a free wall up to 6 feet and an overall height of 9 feet; deeper cuts must be tiered.
5. Walls and Fences in Combination with Retaining Walls. To accommodate possible differences in grade between two properties, or between a property and a public right-of-way, the Planning Director may approve walls and fences constructed in combination with retaining walls, which have an overall height in excess of the maximum wall height allowed by Paragraphs C.1 through C.4 of this Section. However, walls and fences constructed in combination with retaining walls, which are located adjacent to a public right-of-way, shall: have a maximum retaining wall height of 3 FT and a maximum free wall height equal to the maximum wall heights allowed by Paragraphs C.1 through C.4 of this Section. 6. Tiered Retaining Wall Design. In cases where more than 3 FT of earth retention is necessary adjacent to a public right-of-way, retaining walls shall be tiered as exemplified in Figure 6.02-1 (Tiered Retaining Wall Design Concept).
Full Breakdown
Ontario Development Code Section 6.02.020.C.5 (residential) and 6.02.025.C.3 (nonresidential) allow the Planning Director to approve walls and fences built in combination with retaining walls that exceed the base height limits, to accommodate grade differences. However, where such a combination wall is adjacent to a public right-of-way it must have a maximum retaining wall height of 3 feet, a maximum free wall height of 6 feet, and a maximum overall height of 9 feet. Where more than 3 feet of earth retention is needed adjacent to a public right-of-way, retaining walls must be tiered as shown in Figure 6.02-1 (Tiered Retaining Wall Design Concept) (6.02.020.C.6; 6.02.025.C.4). A separate building 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 (City Building Permit FAQs). Retaining walls visible to the public must meet the decorative-masonry material standards of 6.02.020.B.
Violations & Fines
Over-height or untiered retaining walls adjacent to the right-of-way require Planning Director approval; unapproved work is subject to stop-work orders and Community Improvement enforcement, plus building-permit penalties for walls over 2 feet built without a permit.
Frequently Asked Questions
How tall can a retaining wall be next to the street?
What if I need to retain more than 3 feet of earth?
Do retaining walls need a permit?
Sources & Official References
Other rules in Ontario
California rules heatmap·Compare Ontario to another location·View the California fence regulations overview
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Retaining Walls in Nearby Cities
How other cities in San Bernardino County handle retaining walls.