Across Ventura County and the Conejo Valley, an ADU's five-year return depends on three things — what it costs to build in your city, what it rents for, and the value it adds — and the gap between cities is wider than most owners expect.
How to read a 5-year ADU ROI
Five years is long enough to capture the real return: cumulative net rent (rent minus taxes, insurance, maintenance, and vacancy) plus the value the ADU adds on resale, against the build cost. In this region the five-year picture is usually strongly positive because rent is high relative to build cost. The right tool for your specific lot is the ADU rental ROI calculator, which lets you set city, build cost, rent, and financing.
Build cost and rent by city (2026 planning estimates)
These are regional planning ranges for a detached unit, not quotes — confirm with contractor bids and a local rent survey.
| City | Typical build (det. 600–800 sf) | Typical rent / mo |
|---|---|---|
| Simi Valley | ~$185,000 | ~$2,400 |
| Moorpark | ~$185,000 | ~$2,400 |
| Camarillo | ~$190,000 | ~$2,500 |
| Thousand Oaks | ~$200,000 | ~$2,700 |
| Newbury Park | ~$200,000 | ~$2,650 |
| Oak Park | ~$205,000 | ~$2,800 |
| Westlake Village | ~$235,000 | ~$3,300 |
| Calabasas | ~$240,000 | ~$3,400 |
Three ADU sizes, three return profiles
- Studio / Jr. 1-bed (~400–500 sf): lowest build cost, fastest payback, strongest cash-on-cash; rents lag larger units but cost much less.
- 1-bed (~600–800 sf): the sweet spot in this region — broad tenant demand, strong rent-to-cost ratio.
- 2-bed (~900–1,200 sf): highest rent and value-add, but build cost rises faster than rent, slightly compressing ROI; best when housing family or for higher resale value.
The bottom line
Because rent scales with build cost across these cities, the five-year ROI band is surprisingly consistent — efficient builds in any of them tend to pay back in roughly 9–13 years and add value near or above cost. The bigger levers are build efficiency, financing cost, and unit size, not which city. Model your specific case with the calculator and confirm the local ADU rules.
Frequently Asked Questions
What is the 5-year ROI on an ADU in Ventura County?
Typically strongly positive — cumulative net rent plus a value-add near or above build cost. The exact figure depends on build cost, rent, financing, and unit size; use the ADU ROI calculator.
Which city has the best ADU ROI?
ROI is surprisingly similar across cities because rent scales with build cost. Build efficiency, financing, and unit size matter more than the city.
What ADU size has the best return?
A ~600–800 sf one-bedroom is usually the sweet spot in this region — broad demand and a strong rent-to-cost ratio. Studios pay back fastest; 2-beds add the most value.
How do I estimate my ADU's return?
Use the ADU rental ROI calculator with your city, build cost, rent, and financing, then confirm build cost with contractor bids.
