In short
- 565 ADU permits since 2018.
- 101 in 2025, up 35% from 2024.
- Typical permit time: 221 days from application to permit (median of 53 permits with both dates recorded).
About this data
- Source: California HCD Housing Element Annual Progress Reports. The state data does not say whether an ADU is detached, attached, a garage conversion or a JADU, so most records show as 'unknown'. Permit valuations are not published in this source. Timelines use the application date the city reported to the state, matched to the permit where possible; some cities report their planning application date, so timelines can include planning review. Each project is counted once, in its building-permit year (or completion year when no permit date was reported).
- Unincorporated Ventura County covers the parts of the county outside any city, such as Oak Park, Somis, Meiners Oaks, Oak View and Santa Rosa Valley. The county reports them together; its page breaks them down by community using each permit's location (Census designated places), with rural areas counted separately.
Permits by year
Permits by year and type (table)
| Year | All ADU permits | Garage conversions | Detached |
|---|---|---|---|
| 2018 | 62 | — | — |
| 2019 | 46 | — | — |
| 2020 | 60 | — | — |
| 2021 | 30 | — | — |
| 2022 | 74 | 0 | 0 |
| 2023 | 117 | 12 | 0 |
| 2024 | 75 | 0 | 0 |
| 2025 | 101 | 0 | 0 |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
Not counted above: 455 approved projects with no building permit reported yet.
By community
Where these ADU permits are, by community. The most active are Meiners Oaks, Mira Monte and Oak View.
| Community | ADU permits | Share |
|---|---|---|
| Meiners Oaks | 56 | 10% |
| Mira Monte | 50 | 9% |
| Oak View | 45 | 8% |
| El Rio | 24 | 4% |
| Channel Islands Beach | 19 | 3% |
| Bell Canyon | 17 | 3% |
| Casa Conejo | 17 | 3% |
| Oak Park | 16 | 3% |
| Santa Rosa Valley | 15 | 3% |
| Lake Sherwood | 14 | 2% |
| North Ventura Avenue | 10 | 2% |
| Piru | 9 | 2% |
| 4 other communities (listed below) | 31 | 5% |
| Rural areas outside any designated community | 241 | 43% |
| Location not available | 1 | <1% |
Show the other 4 communities
| Community | ADU permits | Share |
|---|---|---|
| Somis | 9 | 2% |
| Saticoy | 8 | 1% |
| Nyeland Acres | 7 | 1% |
| Santa Susana | 7 | 1% |
Communities are Census designated places, matched from each permit's location.
ADU rules in Unincorporated Ventura County
State law check: HCD found the county's 2023 ordinance noncompliant (September 5, 2023); the county amended it in 2024. We haven't seen HCD's response.
| Rule | Unincorporated Ventura County's code | State law guarantees |
|---|---|---|
| Maximum size | 850 sq ft (1 bedroom) or 1,000 sq ft on lots up to 9,000 sq ft; 1,200 sq ft on larger lots; 1,800 sq ft on 10 acres or more. Junior ADU 500 sq ft. | At least 850 sq ft (1,000 sq ft with 2+ bedrooms) must be allowed; an 800 sq ft detached ADU always is. Conversions of existing space have no size cap. Junior ADU: up to 500 sq ft. |
| Height | Detached: 16 ft (18 ft near transit, plus 2 ft); taller if set back 20 ft. Attached: 25 ft or the house's limit. 2 stories. | Detached: at least 16 ft (18 ft within ½ mile of transit, plus 2 ft for a matching roof). Attached: 25 ft or the zone's limit, whichever is lower. |
| Setbacks | 4 ft side and rear. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space per ADU or per bedroom, whichever is less, unless exempt; none for junior ADUs. | At most 1 space; none within ½ mile of transit and in several other cases. No replacement parking when a garage is converted. |
| Owner living on site | None for ADUs. Junior ADU: required. | None for ADUs. A junior ADU that shares a bathroom with the house requires the owner to live in one of them. |
| How many on a single-family lot | A converted ADU, a detached (or attached) ADU and a junior ADU; one ADU in open-space and agricultural zones. | One ADU converted from existing space, one junior ADU and one new detached ADU (up to 800 sq ft). From January 1, 2027: two new detached ADUs (a city then needn't allow a junior ADU on that lot). |
| Short-term rentals | More than 30 days, with a recorded deed restriction. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- These rules cover areas outside the Coastal Zone; coastal lots follow the county's coastal zoning ordinance, and junior ADUs aren't allowed there until its update is certified.
- Free pre-approved detached ADU plans are available.
Where local rules conflict with state law, state law controls. Sources: Ventura County Non-Coastal Zoning Ordinance § 8107-1.7 (last amended Jun 4, 2024) · HCD findings (Sep 5, 2023); HCD's list of review letters; California ADU rules. Verified Sep 29, 2026. Rules change and every lot is different: confirm with the county before you design.
How long permits take
| Type | Median days, application to permit | Middle half | Permits |
|---|---|---|---|
| Garage conversion | not reported | ||
| Junior ADU (JADU) | too few to say | 1 | |
| Unclassified | 229 | 134 – 378 | 52 |
Middle half: the range covering the middle 50% of permits (a quarter were lower, a quarter higher).
Read more: ADU permit times across Ventura County · How long ADUs take to build
From permit to completion
Of the 265 ADU permits Unincorporated Ventura County reported issuing from 2020 through 2023, 160 (60%) have a completion reported to the state. For those, the median time from permit to completion was 12 months.
The state reports don't record expired or cancelled permits, and a completion the city hasn't reported looks the same as an unfinished project, so the share is a floor. Years with incomplete reports are left out.
What neighbors declared as cost
Cost data (declared permit valuations) is not published for this area in these sources.
Read more: How to choose an ADU builder
An ADU builder serving Unincorporated Ventura County? Feature your business on this page.
Questions about ADUs in Unincorporated Ventura County
How many ADUs have been permitted in Unincorporated Ventura County?
Public records show 565 ADU permits in Unincorporated Ventura County from 2018 through 2025. 101 in 2025, up 35% from 2024. These counts come from the city's reports to the state, which place a project in its completion year when no permit date was reported.
How long does an ADU permit take in Unincorporated Ventura County?
Among the 53 ADU permits in Unincorporated Ventura County with both dates recorded, half were issued within 221 days of the application; the middle half took 135 to 378 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Unincorporated Ventura County?
California law allows ADUs on most lots with a house, including in Unincorporated Ventura County, but what you can build depends on your lot, local rules and utilities. This site shows permits, not eligibility. See California ADU rules.
Where do I apply for an ADU permit in Unincorporated Ventura County?
Apply with the County of Ventura's Resource Management Agency; an ADU that meets state standards needs only a building permit. Official ADU page.
How current is this?
- State annual progress reports: through 2025 (published once a year)
How our data works · Download the data · Free to reuse with credit to SoCal ADU Tracker (socaladutracker.com), under CC BY 4.0.