The Complete Ventura County ADU Requirements Guide
If you’re planning to build an accessory dwelling unit (ADU) in Ventura County, knowing the rules upfront helps avoid problems later. An ADU is a self-contained housing unit that shares a lot with a larger main residence. It can be attached to the primary home, detached elsewhere on the lot, or created by converting existing space.
This guide outlines Ventura County’s ADU requirements and how Samara can help bring your project to life.
Ventura County ADU regulations at a glance
ADUs are allowed in all residential zones in unincorporated Ventura County, with state law guiding much of the process. The county reviews ADU applications within 60 days of submittal, and most projects take three to four months to permit.
Below are the key rules for building an ADU in unincorporated areas. Incorporated cities like Ventura or Oxnard may have separate requirements.
Size and lot requirements
There is no minimum lot size for building an ADU in unincorporated Ventura County. However, the size of ADU you can build is determined by your lot size and the number of bedrooms in the unit.
- Detached ADUs: The base maximum is 850 square feet for studios and one-bedroom units, and 1,000 square feet for units with two or more bedrooms. On lots over 9,000 square feet, that limit increases to 1,200 square feet. On parcels over 10 acres, detached ADUs can be up to 1,800 square feet. Height is capped at 16 feet, or 18 feet if the property is near transit or includes a multi-story building. If set back at least 20 feet from all property lines, a detached ADU may match the height of the primary home, up to the zoning district’s standard limit. An additional 2 feet is allowed to match the roof pitch of the main house.
- Attached ADUs: Attached ADUs follow the same size limits as detached ones: 850 square feet for one-bedrooms, 1,000 square feet for two or more bedrooms, and up to 1,200 or 1,800 square feet on larger parcels.
- Junior ADUs (JADUs): JADUs must be located within the existing walls of the main home and are limited to 500 square feet.
All ADUs must have at least 4-foot side and rear setbacks. Special limits apply in certain areas. In the Ojai Traffic Impact Area, ADUs must be on parcels of at least 1 acre and are capped at around 700 square feet. In the Arroyo Santa Rosa/Tierra Rejada Groundwater Impact Area, ADUs range from roughly 700 to 1,200 square feet, depending on lot size.
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Parking requirements
Ventura County requires one off-street parking space for new ADUs, or two if the unit has two or more bedrooms (capped at two total). This requirement is waived if the property is near transit, in a historic district, within a permit-only parking zone without permits, or near a car-share vehicle. No parking is required for conversion ADUs or JADUs.
Zoning eligibility
ADUs are permitted on any lot zoned for residential or mixed-use in unincorporated Ventura County. This means that if your property’s zoning allows residential use (standard single-family zones like R1, rural residential/agricultural zones, multi-family or residential mixed-use zones), you are eligible to build an ADU. The ADU must be located on the same parcel as the primary dwelling; you can add an ADU to a lot that has an existing or proposed main house, but you cannot build an ADU on a vacant lot by itself.
Number of ADUs allowed
Single-family lots in Ventura County can have one ADU (attached or detached) and one JADU per property, for a total of two units in addition to the main home. Detached ADUs on these lots can be up to 1,000 square feet, or larger on parcels above 9,000 square feet.
Multi-family lots can have up to eight new detached ADUs, plus interior ADUs created by converting non-livable areas (like storage rooms or garages), up to 25% of the existing unit count.
Meet the KurodasStreamline your ADU in Ventura County
If you’re looking to build an ADU, Samara makes it easy. We handle everything from permits to installation and even offer our own financing. Call us at 650-420-2607 to schedule a 15-minute consultation and discover how simple adding a Backyard ADU can be.
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