ADU rules in Vallejo

Ordinance No. 1890 N.C.(2d) (adopted 9-8-2026, effective 10-8-2026) repealed and replaced VMC Chapter 16.303, and sec. 16.303.12(A) allows a detached ADU on the same lot as an existing or proposed single-family or multifamily dwelling. A single-family lot may have one detached ADU alongside one JADU and one attached or conversion ADU (three units at most, sec. 16.303.14(A)); a lot with an existing multifamily building may have up to eight detached ADUs, never more than its existing units, and a lot with a proposed multifamily building two. Table 16.301-A marks ADUs "P" (permitted) in the RR, RLD, RMD, RHD, NMX, DMX, WMX, NC, CC and RC districts and not in WC, O, M, IL, IG, PROS, RCN or PS. New detached units take 4 ft side and rear setbacks and may be 16 ft tall (18 ft plus 2 ft for a roof pitch matching the house within 1/2 mile of a major transit stop or high-quality transit corridor, and 18 ft on a lot with a multistory multifamily building).

Attached ADUs (new space sharing at least one wall with the house, sec. 16.303.11(A)) and conversion ADUs (space inside the existing or proposed house or inside an existing accessory structure such as a detached garage, sec. 16.303.10(A)) are both allowed; a single-family lot gets one attached or conversion ADU plus one JADU and one detached ADU (sec. 16.303.14(A)). Attached units take side and rear setbacks of no more than 4 ft and may reach 25 ft or the zone height for the house, whichever is lower; conversions need no setbacks, keep the existing height, and may add up to 150 sq ft to an accessory structure for ingress and egress. On multifamily lots, conversion ADUs may occupy non-livable space (storage rooms, boiler rooms, attics, basements, garages) up to 25 percent of the existing units, or at least one. A JADU of up to 500 sq ft must sit within the walls of the single-family house, an attached garage included, one per lot (sec. 16.303.13).

Sec. 16.303.12(C)(2) caps a detached ADU at 1,200 sq ft, a cap that does not apply to the detached units allowed on multifamily lots by Gov. Code sec. 66323(a)(4). Sec. 16.303.11(C)(2) caps an attached ADU at the lesser of 50 percent of the floor area of the existing or proposed house or "at least" 850 sq ft (studio or one bedroom) or 1,000 sq ft (two or more bedrooms); Gov. Code sec. 66321(b)(3) still guarantees an ADU of at least 800 sq ft of interior livable space with 4 ft side and rear setbacks, so the effective attached cap is 800 sq ft for a house under 1,600 sq ft. Conversion ADUs have no minimum or maximum (sec. 16.303.10(C)), JADUs run 190 to 500 sq ft, and new attached and detached units must be at least 190 sq ft. Vallejo measures "floor area" while state law states its 800, 850 and 1,000 sq ft floors in interior livable space, and sec. 16.303.12(F) bars lot coverage, floor area ratio, open space and landscaping rules from precluding an 800 sq ft detached ADU. Until 10-8-2026 the repealed 2021 text (old sec. 16.303.02(E)) capped attached units at 50 percent or 1,200 sq ft.

Sec. 16.303.08(J) states that owner occupancy "shall not be required for ADUs" and applies only to a JADU that shares sanitation facilities with the house (the owner may live in either the house or the JADU), matching Gov. Code sec. 66315 and sec. 66333(b) as amended by SB 543 and AB 1154. The recorded JADU deed restriction in sec. 16.303.13(I) now covers only separate sale and the unit's size and attributes. The repealed 2021 chapter (old sec. 16.303.03(G) and 16.303.05), which Municode still prints, required owner occupancy and a deed restriction for every JADU; that clause yielded to sec. 66333(b) on 1-1-2026 and leaves the code on 10-8-2026. The city's March 2026 ADU Mini-Guide still tells owners they must live in the house or the JADU and record a deed restriction, which is stale.

Sec. 16.303.08(H)(1) requires one off-street space for each ADU, which may be tandem on an existing driveway, but none for any ADU or JADU authorized by Gov. Code sec. 66323. Sec. 16.303.08(H)(3) waives the space for an ADU of 500 sq ft or less (a local exemption beyond state law, per the 8-4-2026 staff report), within 1/2 mile walking distance of public transit, in an architecturally or historically significant historic district, entirely within the house or an accessory structure, where on-street permits are required but not offered, or within one block of a car share vehicle. JADUs need no parking (Table 16.508-B: "Junior Accessory Dwelling Unit, None"), and a garage, carport or parking space demolished or converted for an ADU or JADU need not be replaced (sec. 16.303.08(I)). The local list omits the Gov. Code sec. 66322(a)(6) waiver for an ADU applied for together with a new house or multifamily building, which applies anyway, and sec. 66314(d)(10)(A) caps any requirement at one space per ADU or per bedroom, whichever is less.

Sec. 16.303.03(B) requires a building permit application for an ADU or JADU that meets the chapter to be "approved ministerially, without a public hearing or discretionary decision." Under sec. 16.303.06 the Building Division decides completeness within 15 business days, sends complete applications to the Planning Division for a compliance check, and must approve or deny within 60 days or the application is deemed approved; appeals of an incompleteness finding or a denial go to the Director. ADUs are exempt from design review (sec. 16.604.01), development review (sec. 16.605.01(B)(9)) and historic certificates of appropriateness (sec. 16.614.09(B)(4)). Until 10-8-2026 the repealed 2021 chapter ran a separate Planning Division zoning compliance review (Chapter 16.603) before the building permit for units over 800 sq ft. Two older chapters still route ADUs on view-district and hillside lots toward hearings or a use-permit-style hillside permit (see caveats), which Gov. Code sec. 66317 and sec. 16.303.15 override.

Sec. 16.303.08(K) allows an ADU or JADU to be rented "only for a term longer than 30 consecutive days," and sec. 16.303.08(L) bars selling or conveying either unit apart from the house except under Gov. Code sec. 66341 (qualified nonprofit sales to low-income buyers); Vallejo has not opted into sec. 66342 ADU condominiums. State law independently requires terms longer than 30 days for JADUs (sec. 66333(g)) and state-exempt units (sec. 66323(e)), while for other ADUs sec. 66315 allows a local minimum of "30 days or longer," so Vallejo's rule runs one day past it for those units and yields under the chapter's own state-law clause (sec. 16.303.15). The repealed 2021 chapter enforced its over-30-day term through a recorded deed restriction (old sec. 16.303.05), which Ord. 1890 dropped. Vallejo has no short-term rental permit program; the transient occupancy tax chapter treats stays of 30 consecutive days or less as transient and requires an operator registration permit (sec. 3.19.020, 3.19.060).