ADU rules in Ventura County

Outside the Coastal Zone, the Non-Coastal Zoning Ordinance (NCZO) allows a detached ADU with an existing or proposed single-family or multifamily home in every zone that allows housing: R1, R2, RES, RPD, R/MU, RHD, RA, RE, RO and CPD/CBD, plus the OS, AE and TP open space, agricultural and timberland zones (NCZO 8107-1.7.4, 8107-1.7.5(a)). A new detached unit of up to 850 sq ft with 4-foot side and rear setbacks needs only a building permit on a single-family lot in the residential zones (8107-1.7.4(b)); a larger detached unit, or any ADU in OS, AE or TP (one per lot there), first gets a ministerial Zoning Clearance (8107-1.7.5). On multifamily lots the codified text still says two detached ADUs (8107-1.7.4(d)), but the County's ADU page acknowledges the state count now governs: up to eight on a lot with an existing multifamily building, never more than its existing units, and two with a proposed one (Gov. Code 66323(a)(4)). In the Coastal Zone the certified Coastal Zoning Ordinance (CZO) still allows one ADU per lot with a single-family home and requires a Coastal Development Permit, issued by the Planning Director without a public hearing, for any new detached unit (CZO 8175-5.1.1, 8175-5.1.1.2), with state standards applied where applicable until the 2025 coastal update (Ord. 4654) is certified.

One ADU created inside the existing or proposed space of a house or an existing accessory structure (garage conversions included, with up to 150 sq ft added for entry and exit) needs only a building permit in the residential zones (8107-1.7.4(a)), and a new attached addition is approved by ministerial Zoning Clearance under the same lot-size caps as a detached unit (8107-1.7.3(b), 8107-1.7.5). A single-family lot in a residential zone may combine two ADUs (one conversion plus one new detached or attached unit) with one JADU; in OS, AE and TP only one ADU is allowed and no JADU, and an ADU inside the house there must have its own exterior entrance and no interior connection (8107-1.7.5(b), (h), 8107-1.7.6(a)). JADUs of up to 500 sq ft are allowed inside a single-family house, including an attached garage, in the R1, R2, RES, RA, RE and RO zones, one per lot (8107-1.7.6). In the Coastal Zone a conversion inside the existing house or an attached accessory structure is exempt from a Coastal Development Permit and gets a Zoning Clearance (CZO 8175-5.1.1.1), an attached addition needs a Coastal Development Permit, and the County states that JADUs are not allowed in coastal areas until Ord. 4654 is certified.

Section 8107-1.7.5(g) caps an attached or detached ADU by lot size: on lots of 9,000 sq ft or less, 850 sq ft with one bedroom or as an efficiency unit and 1,000 sq ft with more than one bedroom; 1,200 sq ft on lots over 9,000 sq ft but under 10 acres; and 1,800 sq ft on lots of 10 acres or more, with no percent-of-house limit, and an 850 sq ft unit with 4-foot setbacks is always allowed regardless of lot coverage, floor area ratio, open space, front setback or lot size (8107-1.7.5(j)). Units approved by building permit alone follow the state pathway instead: a new detached ADU of up to 850 sq ft on a single-family lot, conversions of existing space with no cap beyond a 150 sq ft entry expansion (in OS, AE and TP a conversion is held to the lot-size caps, 8107-1.7.5(h)), and detached units on multifamily lots, which the codified text caps at 1,200 sq ft even though Gov. Code 66323(b) authorizes no size standard for them (8107-1.7.4); JADUs are capped at 500 sq ft. Detached ADUs may be 16 feet tall (18 feet within one-half mile walking distance of a major transit stop or high-quality transit corridor, plus 2 feet for a matching roof pitch, or on a lot with a multistory multifamily building), may reach the house's height limit if set back 20 feet from every property line, and never exceed two stories; attached ADUs may be 25 feet or the house's limit, whichever is lower (8107-1.7.5(d)). The NCZO measures 'total floor area' to the exterior walls (8107-1.7.2), while since January 1, 2026 the state floors of 850 and 1,000 sq ft count interior livable space (Gov. Code 66321(b)(2), SB 543), so where the state measure allows more it governs (8107-1.7.1). In the Coastal Zone the certified CZO still caps a permit-track ADU at 700 sq ft of gross floor area (8175-5.1.1.2(b)), which the County reviews against state standards until Ord. 4654 brings the coastal caps in line with the NCZO tiers in interior livable space.

No owner occupancy is required for an ADU: Section 8107-1.7.7(e)(3)(a) says the owner of a lot with an ADU does not have to live in the house or the ADU, consistent with Gov. Code 66315. JADUs are the exception, and here the codified text lags state law: 8107-1.7.7(e)(3)(b), as amended by Ord. 4633 in 2024, still requires the owner to live in the house at application and afterward for every JADU, while AB 1154 limited the requirement, from January 1, 2026, to JADUs that share sanitation facilities with the house (Gov. Code 66333(b)), and both Gov. Code 66339.5 and the NCZO's own 8107-1.7.1 make state law govern. The County administers the state rule: its non-coastal JADU deed restriction form, revised February 26, 2026, recites an owner-occupancy requirement only if the JADU shares sanitation facilities and omits the occupancy covenant that 8107-1.7.7(f)(2)(d) still lists, and the August 2026 draft ADU Guidebook says the same, although the ADU web page still prints the universal rule. In the Coastal Zone the certified CZO 8175-5.1.1.2(n) still requires the owner to live in the house or the ADU at application for a permit-track ADU, but the County's Coastal Zone ADU Affidavit asks only for the over-30-day rental and no-separate-sale commitments, and pending Ord. 4654 would drop owner occupancy for coastal ADUs and JADUs entirely.

ADUs approved by building permit alone under 8107-1.7.4 (conversions of existing space, a detached unit of up to 850 sq ft on a single-family lot, and the multifamily-lot units) are exempt from the parking standards (8107-1.7.4(f); parking table 8108-4), and JADUs need none (8107-1.7.6(e)). A larger or attached ADU approved by Zoning Clearance needs one covered or uncovered space per ADU or per bedroom, whichever is less, which may be tandem on a driveway or in a front or interior side setback, unless the unit is within one-half mile walking distance of public transit, in a historic district, part of the house or an accessory structure, where on-street permits are required but not offered to its occupant, within one block of a car-share vehicle, or applied for with a new home and meeting one of those tests (8107-1.7.5(c)); the County's draft Guidebook also treats a studio as needing no space. A garage, carport or covered space converted or demolished for an ADU need not be replaced (8107-1.7.5(c)(3)); a leftover 2018 footnote in the parking table still speaks of replacement parking but yields to that section and Gov. Code 66314(d)(11). In the Coastal Zone the certified CZO requires one space for a permit-track ADU with similar exemptions, still provides for replacement parking when a garage is demolished (in any configuration), and bars setback or tandem ADU parking in the North Coast and Santa Monica Mountains fire areas unless the Fire Marshal clears access (8175-5.1.1.2(e)-(h), 8176-3.7), subject to the state limits the County applies where applicable.

Review is ministerial: ADU and JADU applications that meet 8107-1.7 'shall be considered and approved ministerially without discretionary review or a hearing' (8107-1.7.7(a)); units meeting the state-style standards of 8107-1.7.4 and all JADUs are approved directly with a building permit, and all other ADUs with a ministerial Zoning Clearance from the Planning Director before the building permit (8107-1.7.7(b)), with no variances except cultural-heritage deviations and reasonable accommodations. Applicants also file an Estimated Rental Amount form for the County's Housing Element monitoring (Program HE-Z). The NCZO still calls ADU decisions final and not appealable (8111-7.2(a), 8111-7.6(b)), but since January 1, 2026 Gov. Code 66317(d) requires an appeal to the Board of Supervisors or Planning Commission for incompleteness determinations and denials, decided within 60 business days. In the Coastal Zone a conversion inside existing space gets a Coastal Development Permit exemption and a Zoning Clearance, while other ADUs need a Coastal Development Permit in the form of a Planning Director-approved Planned Development Permit, decided after public notice and written comments but without a public hearing (CZO 8175-5.1.1.2, 8181-13); since AB 462 (effective October 10, 2025) those decisions must come within 60 days and are no longer appealable to the Coastal Commission (Gov. Code 66329).

An ADU and a JADU may each be rented separately from the house, but every rental must be for a term longer than 30 consecutive days (8107-1.7.7(e)(1)-(2)), and the codified text requires a recorded deed restriction saying so for each ADU (8107-1.7.7(f)(1)); state law independently requires the over-30-day term for state-pathway ADUs and for JADUs (Gov. Code 66323(e), 66333(g)). The County's short-term rental rules also exclude ADUs outright: no homeshare or short-term rental permit may issue for 'a dwelling that was permitted as a second dwelling unit or an accessory dwelling unit', both in the Ojai Valley Temporary Rental Unit (TRU) overlay, where short-term rentals are barred except on 2018 landmark properties and owner-present homeshares need an annual Zoning Clearance (NCZO 8109-4.6), and in the Coastal Zone, where short-term rentals and homeshares otherwise need an annual permit, a business license and transient occupancy tax (CZO 8175-5.21); the certified CZO separately bars transient occupancy of ADUs (8175-5.1.1.2(m)). An ADU cannot be sold or conveyed separately from the house except as Gov. Code 66340 et seq. allows, which the County's draft FAQ reads as the 66341 qualified-nonprofit sale; no Gov. Code 66342 ADU-condominium ordinance appears in the NCZO, the pending coastal ordinance or the Board record, and a JADU can never be sold separately (8107-1.7.7(e)(4)).