ADU rules in Santa Cruz

Detached ADUs are allowed on lots of any size in every zone that allows residential uses, with an existing or proposed home (SCMC 24.16.120); the governing text is Chapter 24.16 Part 2 as restated by Ord. 2026-02 (adopted 2-24-2026, effective 3-26-2026). A lot with a single-family home, townhome or detached unit may have one statewide-exemption detached ADU (up to 800 sq ft of livable space, 4 ft side and rear setbacks, 16 ft tall, or 18 ft within a half mile of major transit plus 2 ft to match the main roof pitch) and, in addition, one nonexempt ADU that may also be detached, plus a conversion ADU and a JADU (24.16.125(10), 24.16.140(1)(a)). A lot with an existing multi-unit building may add up to eight detached ADUs but never more than its existing unit count, or two with a proposed multi-unit building (24.16.140(1)(b)). Inside the Coastal Zone the same Chapter 24.16 standards apply because Part 2 is not part of the Local Coastal Program, but an ADU that needs a coastal permit must also meet the certified LCP's wetland, stream, habitat, public view and coastal bluff protections (24.12.140(2)(c)).

Attached ADUs (additions to the main home, including to an attached garage) and conversion ADUs carved from any legal home, garage or accessory building are allowed on lots with single-unit buildings (24.16.125(1) and (2), 24.16.140(1)(a)), and a JADU of up to 500 sq ft may be created within an existing or proposed single-unit building in zones that allow single-family homes (24.16.170). Nonexempt attached ADUs follow the main home's zone height and front setback, need only 4 ft side and rear setbacks, and may sit on any story (24.16.141(1)). On a lot with a multi-unit building no nonexempt ADU is allowed, so attached units there are limited to state-exempt conversions of non-livable space such as storage rooms, attics, basements or garages: at least one and up to 25 percent of the existing units (24.16.140(1)(b)(i)). Conversions may expand the existing footprint by 150 sq ft and the height by 2 ft.

SCMC 24.16.141(1), restated by Ord. 2026-02, measures every cap in interior livable space as SB 543 requires, and each cap is a greatest-of test, so the 850 and 1,000 sq ft state floors always apply. A nonexempt detached ADU reaches 1,200 sq ft only on lots with at least 12,000 sq ft of net lot area (the 10 percent rule), while an attached ADU can exceed 1,000 sq ft whenever half the main home's habitable area is larger, with no stated ceiling. Statewide-exemption detached ADUs are capped at 800 sq ft and skip the nonexempt standards entirely, conversions may fill the whole existing building plus a 150 sq ft expansion (not past 1,200 sq ft unless needed for ingress or egress), and JADUs are capped at 500 sq ft. Nonexempt detached units may be 16 ft to the roof peak when closer than 4 ft to a side or rear line and 22 ft at 4 ft or more (3 ft setbacks are allowed up to 16 ft), and attached units follow the zone height for the main home. If site standards would preclude an 800 sq ft unit with 4 ft setbacks, the applicant may waive the percentage-of-home, lot coverage, floor area ratio, open space and front setback limits (24.16.141(10)).

No owner occupancy is required for any ADU. Ords. 2024-23 and 2024-24 (second reading 1-14-2025, effective 2-13-2025 outside the Coastal Zone) were adopted in part to remove owner-occupancy requirements for existing ADUs, answering HCD's 2-6-2024 finding against the old 24.16.140(8) rule, and the city ADU page says owners still holding an owner-occupancy deed restriction can ask Planning to remove it. For JADUs, Ord. 2026-02 follows Gov. Code 66333(b) as amended by AB 1154: the owner must live in the JADU or the main home only when the JADU shares sanitation facilities with it, and not when the JADU has its own bathroom or the owner is a governmental agency, land trust or housing organization (24.16.170(8)). The city ADU page still describes JADU owner occupancy as universal, which the code no longer says.

Outside the Coastal Zone no off-street parking is required for any ADU and parking removed to build one need not be replaced (24.16.141(2)). Inside the Coastal Zone the certified LCP rule in 24.12.240(1) governs: on parcels within the areas shown on the LCP figure 'ADU Parking Required' (a city GIS planning layer of the same name covering parcels close to the coast) each ADU needs at least one off-street space and any parking removed for it must be replaced, while elsewhere in the coastal zone no ADU space is required and a demolished or converted garage, carport or covered space need not be replaced, though driveway or other uncovered spaces removed for an ADU must be replaced for the main home. JADUs need no space anywhere. The Coastal Commission certified this text within LCP-3-STC-25-0040-2-Part A (9-12-2025 hearing, certified 9-22-2025); it rests on the Coastal Act savings clause in Gov. Code 66329(a), because on a plain reading it reaches statewide-exemption ADUs and units near transit that 66322 and 66323 would otherwise exempt.

ADUs and JADUs are principally permitted uses approved through a ministerial building permit with no discretionary review or hearing: a completeness determination within 15 business days and a decision within 60 days of a complete application, with appeals of incompleteness or denial to the Planning Commission (building and fire questions go first to the Board of Building and Fire Appeals) and no appeal to the City Council (24.16.130); no design permit applies in any district. In the Coastal Zone an ADU that is not exempt or excluded (one-to-four-unit residential projects outside the Coastal Appeal Zone and mapped resource and hazard areas are excluded under 24.08.230.2(B)) gets an administrative coastal permit with mailed notice at least 14 days before the decision and no public hearing (24.04.095, 24.04.130 note 1). Discretionary review arises only by the applicant's choice, for example a slope development permit to place a nonexempt ADU within 20 ft of a 30 percent slope (24.16.130(11), 24.08.810); statewide-exemption ADUs never need one.

Neither an ADU nor its associated primary dwelling may be used for transient occupancy or short-term or vacation rental of 30 days or fewer, except a legal ADU property that was in STR use before 11-10-2015 and keeps paying transient occupancy tax (24.16.150(3)); the STR ordinance repeats the bar (24.12.1755), and the city STR page says single-family properties with an ADU cannot get an STR permit for either unit, while multifamily properties may qualify for a non-ADU unit when the owner lives on site, with new non-hosted permits closed and hosted permits capped at 250. A JADU must be deed-restricted to rentals longer than 30 days (24.16.170(9)(c)), as Gov. Code 66333(g) and 66323(e) require for JADUs and state-exempt units. Since 2-13-2025 the city has opted into Gov. Code 66342 ADU condominiums (24.16.165): an ADU and its primary dwelling can be mapped as condominiums (parcel map for four or fewer, tentative and final map for five or more) subject to inclusionary rules; otherwise an ADU cannot be sold separately (24.16.150(1)) except through 66341, and a JADU never can. Rented ADUs must register in the Chapter 21.06 residential rental inspection program, which exempts only unrented legal ADUs (21.06.030(B)).