Santa Monica, CA Fence Regulations: Retaining Walls (2026)
Key Facts
- Permit-exempt height
- 4 feet or less from bottom of footing to top of wall
- Surcharge exception
- Even a short wall needs a permit if it supports a surcharge or impounds flammable liquids
- Wood prohibition
- Retaining walls over 4 ft in Seismic Design Category D, E, or F may not be partially or wholly wood
- Taller wall permit
- Building permit required; must be designed per CBC Sections 1807.2.1–1807.2.4
Summary
Retaining walls four feet tall or less (measured from footing bottom to wall top) are permit-exempt in Santa Monica; taller walls require a building permit and must comply with seismic design standards, including a prohibition on wood construction for walls over four feet in Seismic Design Categories D, E, or F.
§ 8.08.050(c)(5). Work Exempt from Building Permit: Retaining walls that are not over four feet in height measured from the bottom of the footing to the top of the wall, unless supporting a surcharge or impounding flammable liquids.
§ 8.12.140(j). Retaining Walls. Section 1807.2 of the California Building Code is amended to read as follows: 1807.2 Retaining walls. Retaining walls shall be designed in accordance with Sections 1807.2.1 through 1807.2.4. Retaining walls over 4' in height assigned to Seismic Design Category D, E or F shall not be partially or wholly constructed of wood.
Full Breakdown
The permit exemption for retaining walls applies only when the wall does not exceed four feet in height (measured from the bottom of the footing to the top), and when the wall is not retaining a surcharge (additional load) or impounding flammable liquids. Walls exceeding four feet require a building permit. Additionally, for structures in Seismic Design Categories D, E, or F, which applies to much of Santa Monica as a coastal community, retaining walls over four feet cannot be partially or wholly constructed of wood.
Violations & Fines
Building a retaining wall without a required permit constitutes a violation of Article 8 of the Municipal Code, punishable as an infraction (up to $250 fine) or misdemeanor (up to $1,000 fine or up to 6 months jail). The Building Official may issue stop-work orders.
Frequently Asked Questions
My hillside retaining wall is about 5 feet. Do I need a permit?
Can I use treated wood to build a taller retaining wall?
Sources & Official References
Other rules in Santa Monica
California rules heatmap·Compare Santa Monica to another location·View the California fence regulations overview
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Retaining Walls in Nearby Cities
How other cities in Los Angeles County handle retaining walls.