ADU rules in Santa Clara

Detached ADUs are allowed by right in every residential zone (Table 2-1 lists 'Dwelling, Accessory Units' as P in R1-6L, R1-8L and R2 through R6, and Table 2-2 does the same in the Patrick Henry zones) and are approved ministerially through a Zoning Clearance issued with the building permit. A single-family parcel gets one detached ADU, which may be combined with one JADU and one converted ADU (SCCC § 18.60.020.A.1 and A.4); a multifamily or mixed-use parcel gets up to two detached ADUs under the local text (§ 18.60.020.B.1). There is no minimum parcel size (§ 18.60.020.D.1), and a detached unit may be one story and 18 feet or 1.5 stories and 25 feet, with a 15-foot rear setback for the multi-story elements and four-foot setbacks otherwise (§ 18.60.020.E.1-E.2, last amended by Ord. 2077). The two-unit multifamily cap yields to Gov. Code § 66323(a)(4)(A)(ii), which requires up to eight detached ADUs on a lot with an existing multifamily dwelling (never more than the number of existing units).

Attached ADUs, JADUs and conversions are allowed in the same zones. On a single-family parcel the city ministerially approves one attached ADU or one JADU with exterior access, plus one converted ADU made from an existing garage, accessory structure or part of the house; attached ADUs and conversions may add up to 150 square feet for ingress and egress, JADUs may not (SCCC § 18.60.020.A.2-A.4, E.3.g-h, F.2, K.1-K.2). An attached ADU stays on the ministerial track only if it 'matches the height of the existing or proposed building or an existing accessory structure' (§ 18.60.020.A.2.a), so a taller addition, including a second-story ADU over a one-story house, goes to discretionary Architectural Review instead (see permitType). Existing multifamily buildings may convert non-livable space into at least one ADU and up to 25 percent of the existing unit count (§ 18.60.020.B.2). JADUs must sit within the walls of a single-family dwelling and are not permitted in accessory structures (§ 18.60.020.F.2).

Detached ADUs are capped at 1,000 square feet on parcels of 5,500 square feet or less and 1,200 square feet on larger parcels, at 18 feet for one story or 25 feet for 1.5 stories (SCCC § 18.60.020.E.1.a, E.1.e-f, E.2.a). Attached ADUs are capped at '1,000 square feet or 50 percent of the size of the main unit (minimum of 800 square feet), whichever is less', at 25 feet and two stories (§ 18.60.020.E.3.a, E.3.f). JADUs are capped at 500 square feet (§ 18.60.020.F.1), converted space has no size cap (§ 18.60.020.K.6), and the minimum unit is 150 square feet (§ 18.60.020.D.2). Coverage, FAR, open-space and front-setback rules give way wherever they would block an 800 square foot, 18-foot-tall unit with four-foot side and rear setbacks (§ 18.60.020.G, Ord. 2077). The code does not say whether 'unit size' means interior livable space, the measure Gov. Code § 66321(b) now uses for its 850/1,000 and 800 square foot floors.

No owner-occupancy requirement applies to ADUs: § 18.60.020 imposes none and Gov. Code § 66315 bars one. The codified JADU clause still reads universally ('Owner-occupancy is required in the single-family residence in which the junior accessory dwelling unit will be permitted', SCCC § 18.60.020.F.5), but Gov. Code § 66333(b), as amended by AB 1154 effective 1-1-2026, requires owner occupancy only for a JADU that shares sanitation facilities with the main home, and the city's ADU and JADU handout (Rev. 01/26) already states the rule that way ('Required when the JADU shares a bathroom with the single-family dwelling'). A recorded JADU deed restriction barring separate sale and fixing the unit's size and attributes is still required (§ 18.60.020.F.6; Gov. Code § 66333(c)).

'No parking spaces are required for an ADU or JADU' (SCCC § 18.60.020.D.3), and a garage, carport or covered parking structure demolished or converted for an ADU or JADU 'need not be replaced' (§ 18.60.020.D.4). The Chapter 18.38 off-street parking table repeats the rule ('Dwelling, Accessory Unit: No additional parking required'), and voluntary replacement parking for a converted ADU may be covered, uncovered or tandem on a driveway or paved rear yard (§ 18.60.020.K.5). This is more generous than the Gov. Code § 66322 limits, so no state conflict arises.

Most ADUs are ministerial: the city 'shall ministerially approve' the listed single-family and multifamily categories 'through the issuance of a Zoning Clearance' (SCCC § 18.60.020.A-B, § 18.126.020.F-G), and the Planning Division says ADU and JADU projects 'can be submitted as a Building Permit, except for new attached second-story ADUs on a single-story residence, which would require an Architectural Review.' Any ADU outside the ministerial categories, including an attached ADU that does not match the height of the main home, must meet the Chapter 18.10 zone standards and 'undergo Architectural Review in compliance with Chapter 18.120' (§ 18.60.020.C and H): a Director decision on discretionary findings (neighborhood character, the 2014 Single-Family and Duplex Residential Design Guidelines), made at a noticed public Development Review Hearing for second-story additions and projects the Director refers (§ 18.120.020.D and F), and appealable to the Planning Commission. Development Review Hearing agendas show this routinely: PLN25-00227 and PLN25-00355 (second-story ADUs, approved 11-19-2025), PLN25-00194 (a 1,000 sq ft two-story attached ADU, 4-8-2026), PLN25-00483 (a second-floor ADU, 7-8-2026) and PLN26-00047 (an 882 sq ft one-story attached ADU, 9-16-2026, heard only because it was taller than the existing house). That track conflicts with Gov. Code § 66317(a)(1), which requires every ADU permit application to be 'considered and approved ministerially without discretionary review or a hearing', and with the 25-foot attached height floor in § 66321(b)(4)(D); no HCD letter has tested it.

SCCC § 18.60.020.B.4.b says 'All rentals of ADUs and JADUs shall be for a term longer than 30 days' for units approved through the ministerial categories; the clause names JADUs, which exist only on single-family parcels, so it reaches the single-family track as well as multifamily parcels, and it matches Gov. Code §§ 66323(e) and 66333(g) for state-exempt units and JADUs (§ 66315 lets the city require terms of 30 days or longer for other ADUs). The citywide short-term rental program (§ 18.60.250, operative since about November 2024: Administrative Permit, business license and transient occupancy tax; unlimited nights when hosted, 90 nights a year unhosted) still classifies ADUs for its hosted and unhosted limits, so an ADU approved outside the ministerial track through Architectural Review could arguably register, and the city handout says only that 'JADUs may not be used as short-term rentals (less than 30-days)'. ADUs may be rented but not sold separately (Gov. Code § 66314(d)(1)); the city has not opted into ADU condominium sales under § 66342 (a May 2024 council study session on AB 1033 produced no ordinance), and JADUs carry a recorded no-separate-sale deed restriction (§ 18.60.020.F.6).