ADU rules in San Jose

One detached ADU is allowed on any lot with a legally built single-family, duplex, or multifamily main residence (SJMC 20.80.175.A-B, citing Gov. Code 66314 and 66321); Table 20-50 lists ADUs as a permitted use in the R-1, R-2, and R-M districts. Under the city standards a detached unit may reach 18 feet (one story) or 25 feet and two stories, sited behind the main home or at least 45 feet back from the front property line with 6 feet of separation from other buildings. Applicants may instead elect the state-exempt pathway (SJMC 20.80.176, implementing Gov. Code 66323 'or as amended'): today one new detached unit of up to 800 sq ft on a single-family lot, and on multifamily lots up to eight detached ADUs with an existing multifamily building (not exceeding the number of existing units) or two with a new one, per Gov. Code 66323(a)(4). From January 1, 2027, AB 956 raises the single-family count on that pathway to two detached new-construction units (see caveats). Bulletin 210 (updated 09/16/2026) presents both tracks and states they cannot be mixed.

Attached and conversion ADUs are allowed on the same lots as detached ones: on a single-family lot one attached or one detached ADU plus one JADU (two units total in any order), and on multifamily lots one attached or detached ADU under the city standards (SJMC 20.80.175.B). An attached unit must share a common wall or an integral roof structure with the main dwelling, is capped at 50 percent of the existing primary dwelling's floor area (within the 1,000/1,200 sq ft lot-based caps), and may reach 25 feet and two stories. Conversions of existing space, including garages and basements, qualify, and conversions of existing detached accessory structures have no size cap.

Table 20-55 in SJMC 20.80.175.D.1 sets the city caps: 1,000 sq ft on lots up to 9,000 sq ft and 1,200 sq ft above that, with attached units additionally limited to 50 percent of the existing primary dwelling and no maximum for converting an existing detached accessory structure. Minimum size is 150 sq ft (Bulletin 210, 09/16/2026). Heights under the city standards: 18 feet for a one-story detached unit, 25 feet and two stories for two-story detached or attached units. Under the alternative state-exempt pathway (20.80.176 / Gov. Code 66323) a new detached or attached unit is capped at 800 sq ft, with a 16-foot detached height on single-family lots per Bulletin 210; statewide floors in Gov. Code 66321(b)(2), amended by SB 543 effective January 1, 2026, guarantee at least 850 sq ft (1,000 sq ft for more than one bedroom) of interior livable space, which San Jose's caps exceed. JADUs are capped at 500 sq ft (SJMC 20.200.324). Bulletin 210 tells applicants to measure square footage to the exterior finish (see caveats).

Part 2.75 imposes no owner-occupancy requirement for ADUs, and 20.80.175.F affirms an ADU's legal status is unaffected if the property is sold or either dwelling is rented; Gov. Code 66315 bars owner-occupancy conditions on ADUs outright. JADUs are the exception: SJMC 20.80.178 (rewritten by Ord. 31329, June 16, 2026) processes JADUs directly under Gov. Code 66333, which after SB 543 and AB 1154 (effective January 1, 2026) requires owner occupancy only when the JADU shares sanitation facilities with the main home. Bulletin 210 (09/16/2026) now states the same rule in its opening definitions: 'Owner-occupancy of the main home is required if sharing sanitation facilities.' A JADU with its own bathroom carries no owner-occupancy requirement; a JADU deed restriction (Form 313) is still recorded per Gov. Code 66333(c).

No off-street parking is required for any ADU citywide, and covered parking removed or demolished to build an ADU does not have to be replaced: 'No off-street parking spaces are required for an Accessory Dwelling Unit' (SJMC 20.80.175.I, adopted with the December 2023 rewrite). Bulletin 210 (09/16/2026) lists 'Parking Requirements: None' for every ADU type on single-family, duplex and multifamily properties under both the city and state standards tracks. This is more generous than the state ceiling, which would allow up to one space per unit outside the Gov. Code 66322 exemption zones.

Review is ministerial at the building-permit level: ADUs are a permitted use in the residential districts (Table 20-50), 20.80.175 allows them 'notwithstanding' contrary Title 20 provisions, and 20.80.176 provides streamlined ministerial approval for state-exempt units under Gov. Code 66323. Gov. Code 66317 requires a completeness determination within 15 business days and approval or denial within 60 days, without discretionary review or hearing. Even removal of ordinance-sized trees is processed concurrently with the ministerial ADU approval (20.80.177, added February 2026). San Jose also offers preapproved ADU plans and an ADU Ally intake team; converting an ADU into a separately sellable condominium additionally requires a ministerial parcel map under Part 2.76 and Title 19.

ADUs may be rented separately from the main home, but SJMC 20.80.160 (Ord. 30353) flatly prohibits incidental transient occupancy, defined as stays of 30 consecutive days or less, in an ADU, so short-term rentals are not allowed even though the city permits them (with 180-day unhosted caps and TOT) in other dwelling types. JADUs must be rented for terms longer than 30 days (Gov. Code 66333(g) via SJMC 20.80.178). San Jose is an early adopter of the Gov. Code 66342 (AB 1033) opt-in: Part 2.76 (Ord. 31095, June 2024, amended by Ords. 31298 and 31329) lets homeowners convert new or existing ADUs into condominiums sold separately from the primary residence through a ministerial parcel map with lienholder consent, a homeowners association, recorded CC&Rs, and a safety inspection, and the February 2026 update removed the former four-condominium-unit cap per lot. Absent condo conversion or the Gov. Code 66341 qualified-nonprofit path, an ADU cannot be sold separately.