Retaining Walls: Simi Valley vs Ventura
How do retaining walls rules compare between Simi Valley, CA and Ventura, CA?
Simi Valley and Ventura have similar restriction levels.
Simi Valley, CA
Ventura County
Simi Valley requires building permits for retaining walls over 4 feet in height and engineering for walls supporting surcharges. Retaining walls are common in the city's hillside areas and must meet structural and drainage standards.
View full Simi Valley rules →Ventura, CA
Ventura County
Under California Residential Code §R105.2 and California Building Code §105 (both adopted by Ventura via Title 24 Part 2/2.5), a retaining wall over 4 feet measured from the bottom of the footing to the top of the wall — or any retaining wall supporting a surcharge regardless of height — requires a building permit and engineered plans. SBMC Title 9 (Building and Construction Regulations) incorporates the current California Building Standards Code. The City's Block Wall/Fence Submittal Requirements (Form BS 322) detail submittal documents, soil-report needs, and required structural calculations.
View full Ventura rules →Key Facts Comparison
| Fact | Simi Valley | Ventura |
|---|---|---|
| Permit Trigger | Over 4 feet from footing to top | - |
| Engineering Required | Licensed engineer plans | - |
| Drainage | Weep holes or drain pipe required | - |
| Hillside Areas | Additional geotechnical review | - |
| Permit threshold | - | Over 4 ft (bottom of footing to top) — CRC R105.2 |
| Surcharge exception | - | Any height if supporting a surcharge requires permit |
| Engineering required | - | Stamped structural calculations |
| Submittal form | - | City of Ventura BS 322 |
| Coastal zone | - | Coastal Development Permit may also be required |
Highlighted rows indicate differences between cities.
Simi Valley FAQ
Do I need a permit for a retaining wall in Simi Valley?
Yes, if the wall exceeds 4 feet from the bottom of the footing to the top. Walls supporting surcharges (slopes, driveways) need permits regardless of height.
Do retaining walls need to be engineered?
Walls requiring permits must have plans prepared by a licensed civil or structural engineer. Hillside properties may also need geotechnical review.
Can I build tiered retaining walls to avoid permit requirements?
Multiple tiered walls within close proximity may be measured as one wall for height purposes. The Building Division determines whether a permit is required based on the total effective height.
Ventura FAQ
Do I need a permit for a 3-foot retaining wall?
Generally no, if the wall is 4 feet or less from the bottom of the footing to the top AND does not support a surcharge (sloped backfill, driveway loads, pool deck, etc.). If there is any surcharge, a permit is required regardless of height per CRC §R105.2.
Can I stack a fence on top of a retaining wall?
Yes, but the City measures the combined height for zoning purposes, and the fence may require separate permits if it exceeds 7 feet. The retaining wall must also be engineered to handle the additional lateral load from the fence.
Does the coastal zone require extra approvals?
Yes. Retaining walls in the Coastal Zone or on a bluff face require a Coastal Development Permit under the San Buenaventura Coastal Zoning Code in addition to the building permit.
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