Permits · Updated April 17, 2026 · 18 min read
Ventura County ADU Permit Guide (2026)
A per-city breakdown of what you'll actually pay to permit an ADU in Ventura County in 2026, plus plan-review timelines, state-law updates, and the traps most homeowners hit.
Key takeaways
- Total permit costs range $9,800–$26,400 for an 800 sq ft detached ADU, city-dependent.
- State law caps plan review at 60 days — but coastal-zone parcels add 2–5 months for CCC review.
- Impact fees are waived for ADUs under 750 sq ft (state law), but school impact fees still apply.
- No Ventura County city has opted into AB 1033 condo-sale yet — don't count on separate-sale resale value.
- HOAs cannot ban ADUs under AB 670. Full stop.
2026 ADU permit fee comparison — Ventura County cities
The numbers below are for an 800 sq ft detached ADU, the most common scope we see bid. Smaller ADUs drop significantly — sub-750 sq ft waives development impact fees entirely under state law. These are permit-side costs only (not construction). Verified against each city's published fee schedule as of April 2026.
| City | Building Permit | School Impact | Dev Impact (800 sf) | Plan Review | Typical Total |
|---|---|---|---|---|---|
| Simi Valley | $4,100 | $3,950 | Waived* | 45–60 days | $9,800 |
| Thousand Oaks | $5,800 | $4,400 | $6,200 | 60–75 days | $18,600 |
| Moorpark | $3,600 | $3,200 | Waived* | 45–60 days | $9,800 |
| Camarillo | $6,100 | $5,200 | $5,800 | 60–75 days | $21,400 |
| Oxnard (inland) | $3,400 | $2,900 | Waived* | 50–65 days | $10,100 |
| Oxnard (coastal) | $3,400 | $2,900 | Waived* | 90–180 days (CCC) | $11,200 |
| Ventura (inland) | $3,800 | $3,100 | Waived* | 50–65 days | $10,600 |
| Ventura (coastal) | $3,800 | $3,100 | Waived* | 90–150 days (CCC) | $11,800 |
| Ojai | $4,300 | $3,500 | $3,900 | 60–90 days | $15,700 |
| Unincorporated county | $3,900 | $2,800 | Waived* | 45–75 days | $9,900 |
*Waived = state law prohibits impact fees on ADUs under 750 sq ft. Above 750 sq ft, impact fees are charged proportional to the ratio of ADU size to primary dwelling. Totals assume standard submittal; expedited review and structural plan check add to these numbers.
How plan review actually works in 2026
State law (Government Code §65852.2) caps city ADU plan review at 60 days from a complete application. "Complete" is the operative word. Cities routinely reject submittals as incomplete for minor drawing issues, which restarts the clock.
The counties we track that hit the 60-day mark consistently are Simi Valley and Moorpark. Thousand Oaks and Camarillo miss it about 40% of the time — usually because of staffing, not the statute. If your city misses 60 days, you can formally request a hearing to compel issuance, but in practice most homeowners just wait the extra 2–4 weeks.
If your parcel is in the California coastal zone — roughly Pierpont, Ventura Keys, and ocean-facing lots in Oxnard — the city issues the permit, but California Coastal Commission review happens first, and it adds 90 to 180 days. Staying at or under 16 feet in height and respecting existing setbacks usually avoids a CCC appeal.
The 2026 laws that matter
AB 1033 (effective 2024, opt-in)
Permits cities to allow separate sale of an ADU as a condo. Each city must pass a local ordinance to opt in. As of April 2026, no Ventura County city has done so. Plan as if the ADU cannot be sold separately until a specific city ordinance passes.
SB 9 / SB 10 (lot splits + urban density)
SB 9 permits lot splits and up to 4 units on former single-family lots in urbanized areas. It stacks with ADU law in most cities — meaning you can do a lot split, build a second home, and still add ADUs to each lot. Ojai and portions of unincorporated county have local restrictions; urbanized Simi Valley, Oxnard, and Thousand Oaks generally allow it.
AB 2221 + SB 897 (utility meters)
Cities may not require separate water or gas meters for ADUs under 750 sq ft. They may still require separate electric for safety, though most Ventura County cities permit shared sub-metered service. If a contractor's bid includes $4K–$8K for separate meters, verify the city actually requires them.
AB 670 (HOA preemption)
HOA CC&Rs that effectively prohibit ADUs are void as a matter of law. HOAs can require architectural matching (roof, exterior color) but cannot ban ADUs. If your HOA says no, send them the statute and escalate if they persist.
Traps we see homeowners fall into
- Paying permit fees as a line item in the construction contract. Pay permit fees directly to the city yourself. Contractors routinely mark up permit fees 10–30% when they run them through the contract, even on fixed-price bids.
- Not budgeting for school impact fees. These are the single largest surprise cost we see. $3K–$5K minimum, due at permit issuance, not rolled into the construction loan.
- Assuming coastal zone = only oceanfront. The coastal zone extends inland up to 5 miles in some parts of Ventura. Check the California Coastal Commission zone map before you budget a 60-day timeline.
- Signing before the permit is pulled. Contractors who want a 20%+ deposit before permit issuance are asking you to finance their operating capital. No permit, no material, no deposit — pay at permit issuance.
- Skipping the setback check. State law says 4-foot setbacks for ADUs — but local fire code can override this on fire-hazard-severity-zone parcels (parts of Thousand Oaks, Oak Park, Simi Valley hillsides). Verify the setback on your specific parcel, not the state default.
Frequently asked questions
How much does an ADU permit cost in Ventura County in 2026?▾
Total permit costs for an 800 sq ft detached ADU in Ventura County typically run $9,800–$26,400 across cities. Building permit runs $3,200–$6,800, school impact fees $2,900–$5,200, development impact fees are waived under state AB 1033 for new detached ADUs under 750 sq ft but apply above that. Camarillo and Thousand Oaks sit at the high end; Oxnard and Ventura at the low end.
How long does ADU plan review take in Ventura County?▾
State law mandates 60 days from complete-application submittal. In practice, Simi Valley and Moorpark hit 45–60 days. Thousand Oaks and Camarillo run 60–75 days due to higher volume. Oxnard and Ventura inland: 50–65 days. Coastal-zone Ventura parcels (west of Harbor Blvd) add 2–3 months for California Coastal Commission review if the structure is visible from the public coast.
Can I sell my ADU separately from the main house under AB 1033?▾
AB 1033 permits separate sale of an ADU as a condominium unit, but only if the city has opted in. As of April 2026, no Ventura County city has passed an AB 1033 opt-in ordinance. Los Angeles, San José, and San Diego have — Ventura County cities have not. Check city council minutes before counting on this.
Do ADUs need their own utility meters in Ventura County?▾
State law (AB 2221, SB 897) bars cities from requiring separate water and gas meters for ADUs under 750 sq ft. Some Ventura County cities still ask for separate electric sub-metering for tenant billing — check your city. Never sign a contract that includes separate utility hook-ups unless you've verified your city requires them.
Can I build a JADU and a detached ADU on the same lot?▾
Yes. Every single-family lot in California is entitled to one junior ADU (JADU, up to 500 sq ft, within the main house) plus one detached ADU. Multi-family lots get up to two detached ADUs plus one ADU per four existing units. This is state law and every Ventura County city must honor it.
What happens if my ADU plans get flagged by Coastal Commission?▾
If you're in the coastal zone (Pierpont, Ventura Keys, ocean-facing Oxnard parcels), the city can issue the building permit but the CCC reviews first. Expect 2–5 months. Common flags: height over 16 feet, reduced setback from coast, visual impact. Staying at 16 ft and one story usually avoids escalation.
Can an HOA block my ADU?▾
No. AB 670 (2019) and subsequent laws void HOA CC&Rs that effectively prohibit ADUs. HOAs can impose reasonable architectural standards (exterior color, roof material to match) but cannot ban ADUs outright. If your HOA says no, cite AB 670 and escalate to a real estate attorney.
Ready to pull a permit?
You can permit an ADU yourself as an owner-builder — but most homeowners hire a licensed general contractor who handles plan submittal, corrections, and final inspection. See our Find a Contractor page for how to vet one, or read How to Vet a Ventura County Contractor first.
Sources
- California Government Code §65852.2 (ADU law)
- California Government Code §65852.22 (JADU)
- AB 1033 (2023), AB 2221 (2022), SB 897 (2022), AB 670 (2019)
- Per-city fee schedules (Simi Valley, Thousand Oaks, Moorpark, Camarillo, Oxnard, Ventura, Ojai, Ventura County Unincorporated) — retrieved April 2026
- California Coastal Commission mapping data