Do I need a survey to build a fence or ADU?

Building a fence or an Accessory Dwelling Unit (ADU) in Ventura County often requires a land survey, though the specific triggers depend on whether you are in an incorporated city (like Ventura or Oxnard) or an unincorporated area of the county.  At Land Survey Ventura, we can help you figure it all out.

1. Building a Fence or Wall

In many parts of Ventura County, a survey is not strictly required unless you are building on or very close to the property line. However, it is highly recommended to avoid "civil litigation" with neighbors.

• City of Ventura: If you are building a fence or wall within 5 feet of the property line, the city requires the wet signatures of your neighbors on your site plan to verify they agree with the location. If you cannot get their signatures, you must provide a signed and stamped property survey from a licensed surveyor.
• Property Line Construction: In most jurisdictions, including the City of Ventura, you cannot build a new wall directly on a property line without a recorded easement.
• Simi Valley & Others: A building permit is typically not required for fences under 6 or 7 feet, but a "Zoning Clearance" is. To get this, you must submit a plot plan. While a survey isn't always mandatory for the permit, the city notes that a survey is the only "accurate way" to determine the line, and the owner bears all liability if the fence is misplaced.

2. Building an ADU

For an ADU, the requirement for a survey is much more common because of setback regulations.

• Setback Verification: State and local laws usually require a minimum 4-foot setback from side and rear property lines for detached ADUs. If your proposed building is close to these limits, the Building and Safety department will likely require a survey to prove the structure isn't encroaching on the setback or the neighbor's land.

• Topographic Surveys: If your property is on a slope (common in Ojai, Ventura hillsides, or Santa Paula), you will almost certainly need a topographic survey. This is required for the "Grading Permit" to show how water will drain around the new ADU.
• Impervious Surface Limits: A survey is often required to calculate "pervious vs. impervious" surface area. Ventura County has limits on how much of a lot can be covered by concrete or buildings; a survey provides the exact measurements needed for these calculations.

Common "Triggers" That Make a Survey Mandatory:

1. Missing Property Markers: If the original iron pipes or "monuments" at your lot corners are missing or buried.
2. Odd-Shaped Lots: If your property is a "flag lot," is irregularly shaped, or sits on a curved street.
   
3. Hillside Areas: Any construction in designated "Hillside Overlay" zones usually requires land development approval based on a professional survey.
4. Encroachment Issues: If there is an existing fence that doesn't seem to align with your deed, the county will require a survey before they allow a permanent ADU foundation to be poured nearby.

Pro-Tip for Ventura County Homeowners:

Before hiring a surveyor, check VCView (the County’s GIS map). It can give you a rough idea of your property lines, flood zones, and any protected tree overlays (like the Ojai Oak tree protections) that might affect your project's footprint.  For a consultation or questions, call us!