ADUs & additions in Ventura County.
Design-build for ADUs, garage conversions, and additions in southern Ventura County: Thousand Oaks, Simi Valley, Moorpark, Camarillo, Oxnard, Ventura and Oak Park.
HomeAdd works in southern Ventura County, across incorporated cities like Thousand Oaks, Simi Valley, Moorpark, Camarillo, Oxnard and Ventura, plus nearby unincorporated county land reviewed by Ventura County RMA. Each city has its own submittal process; we confirm the correct department during feasibility.
Ventura County parcels often have wildfire, hillside, or agricultural-zoning considerations that affect design. Planning for those constraints early is far more cost-effective than discovering them mid plan-check.
Start by comparing how the proposed space fits the existing house. A garage conversion needs a review of the shell, access and services; a detached ADU needs a siting and utility plan; an addition must connect to the home's layout and structure. For a single-story home, expanding outward and building upward raise different questions. Existing plans and a clear list of priorities help establish what should be evaluated before selecting a design.
Lot layouts vary from closely arranged suburban homes to properties with more open space or sloping ground. Check the actual access route, usable yard, drainage and existing service locations rather than assuming a larger parcel makes construction straightforward. On a parcel with slope or rural conditions, ask which site information is needed before design. These are review questions, not a claim that every Ventura County property requires the same work.
Representative Ventura County cities we serve
Cities named are examples of our regional coverage, not project addresses. We also work in neighboring communities on request.
Ventura County city guides
Detailed pages covering the reviewing department, local site conditions, and the ADU types that work best in each area:
Ventura County service pages by city
Outside Ventura County? See every county and city we serve.
Ventura County homeowner guides
In-depth guides written for Ventura County homeowners — costs, permits, and local conditions:
Relevant HomeAdd services in Ventura County
Ventura County planning & permits — incorporated cities vs. unincorporated county
For parcels inside Thousand Oaks, Simi Valley, Moorpark, Camarillo, Oxnard, Ventura and other incorporated cities, ADU and addition permits go through that city's building and planning department. Each city has its own rules on top of California state ADU minimums.
For unincorporated Ventura County parcels, Ventura County Resource Management Agency (RMA) is the reviewing authority. Their ADU page is the correct starting point.
The county's planning guidance addresses unincorporated land; an incorporated-city property should be checked with that city. Confirm the boundary using the parcel information rather than relying only on a mailing address. Then obtain the applicable checklist, plan requirements and fee schedule. A neighboring city's application experience may be useful context, but it does not establish what your reviewing agency will require.
Budgeting is clearer when the living-space scope is separated from work to existing services, structures and the site. List the rooms and finishes you want, identify anything you want retained, and ask which existing conditions remain unverified. Use the Ventura cost and permit guides linked above to prepare questions, not to predict approval or a final price. HomeAdd's written proposal follows feasibility and design, with the actual scope and allowances documented for the property.
- Ventura County RMA — Accessory Dwelling Units Permit and planning starting point for unincorporated Ventura County. Incorporated cities use their own departments.
- California HCD ADU Handbook State-level ADU baseline rules for every California jurisdiction.
Common site considerations in Ventura County
- Very High Fire Hazard Severity Zones and defensible space.
- Hillside grading and drainage in Simi Valley and Thousand Oaks foothills.
- Agricultural or open-space overlays affecting siting and utility runs.
- Water and sewer capacity, or septic evaluation on unincorporated parcels.
- Setback rules and second-unit siting on larger semi-rural lots.
- Utility panel upgrades on older homes.
Frequently asked questions
Which Ventura County cities does HomeAdd serve?+
HomeAdd serves southern Ventura County: Thousand Oaks, Simi Valley, Moorpark, Camarillo, Oxnard and Ventura, plus nearby unincorporated areas such as Oak Park. Each of those incorporated cities runs its own planning and building review, so we match design and permit strategy to the specific city.
Does Ventura County RMA handle my ADU?+
Ventura County Resource Management Agency (RMA) handles ADUs and additions in unincorporated Ventura County. If your parcel is inside an incorporated city, that city's department reviews the project.
Are there special considerations for Ventura County wildfire zones?+
Yes. Ventura County has significant Very High Fire Hazard Severity Zones. Fire access, materials, defensible space, and, in some cases, sprinklers factor into design and permitting.
How does agricultural or open-space zoning affect ADUs?+
Parcels zoned agricultural or open-space can still allow ADUs under specific conditions, but review is more involved. We confirm zoning and applicable overlays during feasibility.