ADU rules in Santa Barbara County

Detached ADUs are allowed with an existing or proposed home in the unincorporated county's residential, agricultural, resource and residence-allowing commercial and special purpose zones, approved ministerially (the eight incorporated cities, including Santa Barbara and Santa Maria, set their own rules). Each of the three zoning codes, the Land Use and Development Code (LUDC) for inland areas outside Montecito, the Montecito LUDC (MLUDC) and the Article II Coastal Zoning Ordinance (CZO), has two tracks: a state-exempt track in residential and mixed-use zones (LUDC 35.42.015.E, MLUDC 35.442.015.E, CZO 35-142.5) that allows one new detached ADU of up to 800 sq ft with 4-foot side and rear setbacks beside a single-family home, combinable with a converted ADU and a JADU, and a local-standards track (35.42.015.F, 35.442.015.F, 35-142.6) that also reaches AG-I, AG-II and the mountainous and resource management zones but allows only one ADU on the lot. Beside multifamily buildings the codes allow up to eight detached ADUs with an existing building (never more than its existing unit count) or two with a proposed one; in the coastal zone that count took effect only on August 13, 2026 (Ord. 5236), and Municode's CZO text still prints the older limit of two. On local-track lots of half an acre to 20 acres a detached ADU may not sit closer to the street than the house (0.5 to 2 acres) or closer to any property line than the lesser of 100 feet or the house's distance (2 to 20 acres), unless that would prevent an 800 sq ft unit (35.42.015.F.9.e).

One ADU converted from space inside an existing or proposed single-family home or an existing accessory structure, with up to 150 sq ft added for entry and exit, is allowed on the state-exempt track and may share the lot with a JADU (LUDC 35.42.015.E.2; CZO 35-142.5.2). New attached additions, including units stacked above or below an attached accessory structure, follow the local-standards track (F.9.b), and existing multifamily buildings may convert non-livable space such as storage rooms, attics, basements or garages into at least one ADU and up to 25 percent of the existing unit count (E.4). One JADU of up to 500 sq ft is allowed inside a single-family home or its attached garage in the listed residential, agricultural, resource and mixed-use zones, with a recorded Declaration of Restrictions barring separate sale (G.1, G.2, G.5). HCD's October 31, 2025 findings letter says the county's specific JADU kitchen-appliance list (G.3) and its bar on JADUs in other attached enclosed spaces (G.5) exceed Gov. Code 66333(d) and (f), so state law governs those points.

On the local-standards track (LUDC 35.42.015.F.10, repeated in MLUDC 35.442.015.F.10 and CZO 35-142.6.8) a new ADU on a lot of 15,000 net sq ft or less is capped at 850 sq ft with one bedroom or less and 1,000 sq ft with two or more, a new ADU on a larger lot at 1,200 sq ft, an attached unit additionally at 50 percent of the existing home, and a conversion of an existing structure at 1,200 sq ft, but every cap yields where needed to allow an 800 sq ft unit with 4-foot side and rear setbacks. The state-exempt detached unit is limited to 800 sq ft and 16 feet (18 feet within half a mile walking distance of a major transit stop or high-quality transit corridor), conversions on that track carry no size cap beyond the 150 sq ft entry expansion, local-track detached units may be 16 feet as one story or 25 feet as two stories, and attached units 25 feet and two stories but no taller than the house's zone limit. Floor area is measured to the inside of the exterior walls (D.5), an interior measure like the state's interior-livable-space floors in Gov. Code 66321(b)(2), and uninhabitable covered porches, decks and balconies may add up to 20 percent. HCD's October 31, 2025 findings say the 1,200 sq ft cap on detached ADUs beside multifamily buildings (E.5.c) and the front-setback conditions on state-exempt units (E.2.d, E.3.e, E.5.e) are barred by Gov. Code 66323(b), and that the 18-foot limit must add 2 feet for a roof pitch matching the house (66321(b)(4)(B)); the county has not amended the text, so those state rules govern under 66325 and the county's own Ord. 5230 section 14. JADUs are capped at 500 sq ft and every unit must be at least 250 sq ft (G.6, H.1).

None of the three codes requires the owner to live on a lot with an ADU, consistent with Gov. Code 66315, which bars owner-occupant requirements for ADUs. The codified JADU rule (LUDC 35.42.015.G.7, MLUDC 35.442.015.G.7, CZO 35-142.7.7) still requires the owner to occupy the JADU or the house for every JADU unless the owner is a government agency, land trust or housing organization, but since January 1, 2026 Gov. Code 66333(b), as amended by AB 1154, allows owner occupancy to be required only where the JADU shares sanitation facilities with the house, and 66339.5 makes the state JADU article supersede conflicting local text. In practice a JADU with its own bathroom carries no owner-occupancy requirement, while one that shares the home's bathroom does. The JADU Declaration of Restrictions recorded before the building permit covers only the ban on separate sale and the unit's size and attributes (G.2).

State-exempt-track ADUs need no parking (LUDC 35.42.015.E.1.b, which also waives replacement of the house's spaces; CZO 35-142.5.1.b), and JADUs need none (G.8; CZO 35-142.7.8 as rewritten by Ord. 5236). On the local-standards track only a new-construction detached ADU needs a space, one per unit, which may be tandem on a driveway or on a driveway within a setback, and it is waived within one-half mile walking distance of public transit such as a bus stop, in a historic district, where on-street permits are required but not offered to the occupant, or within one block of a car share vehicle (F.11.b); a garage converted or removed for an ADU need not be replaced (F.11.a). In the coastal zone the certified Local Coastal Program adds a coastal-access rule: parking serving the house that is removed to build an ADU or JADU must be replaced on site for parcels outside Isla Vista within a quarter mile of the inland edge of a beach or coastal bluff or south or west of Highway 101, whichever is closer, and for Isla Vista parcels south of El Colegio Road (CZO 35-142.8.7). That rule departs from Gov. Code 66314(d)(11) but stands under the Coastal Act savings clause of 66329(a).

Outside the coastal zone every ADU and JADU needs only a building permit, reviewed by the Building Official ministerially without discretionary review or a hearing within 60 days of a complete application (LUDC 35.42.015.D.1-D.2; MLUDC 35.442.015.D), and LUDC 35.20.040.C exempts ADUs from all planning permits and Development Plan requirements. In the coastal zone an ADU or JADU first needs a Coastal Development Permit decided by the Planning Director with public notice but no hearing (CZO 35-142.4, 35-169.4.1, 35-169.4.2.c.1), then a building permit, and the CDP also applies coastal resource standards (habitat, public views and access, and agricultural protections on AG-I and AG-II lots, 35-142.8.8); all three codes exempt ADUs from design review. State law tightens both processes: Gov. Code 66317 requires approval or denial, not the codified 'consider' (HCD finding 2), within 60 days or the application is deemed approved, plus a written appeal of incompleteness or denial, which the county routes to the Board of Supervisors because it has no local ADU appeal ordinance (Board letter, July 7, 2026); since October 10, 2025 Gov. Code 66329(c) bars appeals of coastal ADU CDP decisions to the Coastal Commission, although CZO 35-169 still lists one. Units that miss the objective standards may seek a discretionary Modification, while variances are barred (35.42.015.D.6, D.8).

All three codes let an ADU or JADU be rented only for terms longer than 30 consecutive days and bar its use as a short-term rental or homestay (and, in the LUDC and MLUDC, a farmstay) in every zone (LUDC 35.42.015.H.5; MLUDC 35.442.015.H.5; CZO 35-142.8.5), matching Gov. Code 66323(e) and 66333(g). The ban reaches the coastal zone even though the county's short-term rental page says STRs and homestays there are otherwise unregulated (transient occupancy tax still applies); inland, STRs are allowed only in certain commercial and special purpose zones and the STR, homestay and farmstay sections each exclude ADUs and JADUs (35.42.245.A.3-A.4, 35.42.193, 35.42.134). ADUs and JADUs cannot be sold separately from the main home except under Gov. Code 65852.26, now 66341 (qualified-nonprofit sales), and the county has adopted no 66342 condominium ordinance. The county's just-cause eviction ordinance exempts housing with a certificate of occupancy issued within the previous 15 years and owner-occupied homes renting out no more than two units or bedrooms, including an ADU or JADU (County Code Sec. 44-22), so it rarely reaches a new ADU.