Cities | San Jose

San Jose Multiplex Rules 2026: SB 9 (2021), R-2 Duplexes and ADU Condos

San Jose has written the state housing laws into its own Municipal Code, with numbers that decide what fits on your lot. This page covers the city's rules for SB 9 (2021), the 2026 rules that let an R-2 lot hold up to five homes, its small-lot subdivision rules, and its option to sell accessory dwelling units (ADUs) as condominiums. All code sections here were read in the San Jose Municipal Code, which is current through Ordinance No. 31330, enacted June 16, 2026.

Start With State Law

Four state laws set the minimum San Jose must allow. SB 9 (2021) allows two primary homes on a lot in a single-family zone, a split into two lots, or both, approved by staff with no hearing. ADU law sets the ADUs and junior ADUs a city must allow. A junior ADU is a unit of 500 square feet or less inside the walls of the house. SB 684 and SB 1123 allow up to 10 lots with 10 homes. SB 79 allows buildings of five or more homes near qualifying transit, and Santa Clara County, where San Jose sits, is one of the seven counties where it took effect July 1, 2026.

San Jose applies those laws through three parts of its zoning code: Part 8 for SB 9, Part 9 for R-2 lots, and section 20.195.450 for small-lot subdivisions. The sections below explain each one. Three 2026 state laws start January 1, 2027 and will apply here too: AB 956 (two detached ADUs per single-family lot), AB 2601 (SB 9 homes and the lot split processed together) and SB 1116 (new SB 684 rules).

San Jose in Numbers

The US Census Bureau estimates 989,814 people in the City of San Jose on July 1, 2025. The California Department of Finance's E-5 estimate for January 1, 2026 counts 980,434 people and 350,935 housing units, of which 23,536 are in buildings of two to four units. The two agencies use different dates and methods.

The city's base zoning sets the starting point. San Jose Municipal Code 20.30.010 says: "The allowable density range for the R-1 districts is one to eight dwelling units per acre." For R-2, the range is eight to sixteen. SB 9 and the 2026 R-2 rules can let a single lot exceed those ranges: four homes on a 5,000 square foot lot works out to more than 34 units per acre.

Three San Jose Options Side by Side

Sources: San Jose Municipal Code 20.30.810 to 20.30.852 and 20.195.450; Gov. Code 65852.28 for the state minimum floor area ratios.

SB 9 in San Jose: Part 8

Part 8 (sections 20.30.800 to 20.30.840, from Ordinances 30707, 30786 and 31298) allows up to two main homes per lot: two houses or one duplex. Section 20.30.820 caps the total: "The total number of units shall not exceed four (4) on any undivided lot or two (2) on each subdivided lot, inclusive of Accessory Dwelling Units (ADUs) or Junior Accessory Dwelling Units (JADUs)."

Size limits are local. Height is 30 feet or two stories, whichever is lower, and 25 feet for a two-story unit within 15 feet of the rear lot line. Side and rear setbacks, the gap between a building and the property line, are 4 feet. Eaves are the only part of a building that may reach into the rear setback, and nothing may come closer than 3 feet to a side line. The floor area ratio (FAR), building floor area divided by lot area, is 0.65 for each lot. On a lot of 5,000 square feet, that is 3,250 square feet of floor area. None of these limits may block a second unit of 800 square feet.

Lot coverage is the share of the lot that buildings may cover. Converting an existing ADU into a new home larger than 1,200 square feet triggers the fire sprinkler rules.

Splitting a Lot in San Jose

Section 20.30.810 sets the shape of the new lots. Each needs 30 feet of frontage on the street and 30 feet of average width. A lot without that frontage can use an access corridor 4 to 7 feet wide, or 12 to 15 feet wide. The wider corridor is required where the street's travel lane is 20 feet or less.

One local rule changes which lots qualify: "A minimum of one (1) dwelling unit shall exist on a lot being subdivided at time of recordation of a Parcel Map for an Urban Lot Split." The parcel map is the recorded map that creates the new lots. A vacant R-1 lot cannot use the SB 9 split in San Jose. State law offers a different route for vacant land: SB 1123 lets a vacant single-family lot of up to 1.5 acres be subdivided into up to 10 lots.

The same section caps ADUs on a duplex lot that is not split: "Lots that contain a two-family dwelling created pursuant to Senate Bill 9 without an Urban Lot Split, shall be limited to one (1) attached accessory dwelling unit or two (2) detached accessory dwelling units per lot." State law bars a split by an owner who already split an adjacent lot "acting in concert" with others. San Jose defines that phrase as "knowing participation in a joint activity or parallel action towards a common goal whether or not pursuant to an express agreement."

SB 9 Paperwork in San Jose

Sections 20.30.830 and 20.30.840 list what the city asks for. You sign a statement, under penalty of perjury, that no tenant lived in an affected unit in the last three years. You record a deed restriction, a rule attached to the property title, saying the units "may not be rented for a term of thirty (30) days or less." For a lot split, you also sign the state's three-year owner-occupancy affidavit. If a city standard would physically prevent the second unit, you may apply for a waiver.

R-2 Lots: Up to Five Homes Under Part 9

Part 9 (sections 20.30.850 and 20.30.852) came from Ordinance 31298, which was on the City Council agenda of January 13, 2026. It allows two houses or one duplex on a single R-2 lot through streamlined ministerial review, meaning staff approve plans that meet the written rules, with no hearing. ADUs and junior ADUs can be added, up to "a maximum of five (5) units on any undivided lot."

The code names two ways to reach five. One is two houses plus a detached ADU, a converted ADU and a junior ADU. The other is a duplex plus two detached ADUs and one attached ADU. Height, setbacks, the 0.65 FAR and lot coverage follow the Part 8 rules. Part 9 does not apply in flood zones, fire hazard zones, earthquake fault zones and similar sites.

R-2 lots cannot be split under SB 9. The code says: "Lot Splits within the R-2 Two-Family Zoning Districts are not permitted under this Section. Subdivision of lots shall only occur through the ministerial small-lot subdivision process established in Chapter 20.195."

Small-Lot Subdivisions Under SB 684 and SB 1123

Section 20.195.450, also from Ordinance 31298, sets San Jose's rules for state SB 684 and SB 1123 projects. "Residential development may incorporate One-family dwelling units, Two-family dwelling units and/or Multifamily dwelling units to not exceed a maximum total of ten (10) units." Side and rear setbacks to neighboring lots are 4 feet. The front setback and height come from the base zone, and the "maximum height may not be waived for a project proposed on a parcel in a single-family zoning district."

Four more local rules apply. ADUs are not allowed except attached ADUs that meet the standards. The city's inclusionary housing rules in Chapter 5.08 apply, which can require some homes to be affordable. Each unit gets its own address. An owner who demolishes housing signs an affidavit with a five-year occupancy history, which matches the state's five-year tenant rule for SB 684. Building permits depend on the approved map, and street, improvement and sewer conditions are handled when the building permit is issued. Projects near Reid-Hillview Airport must meet the airport land use plan.

Selling ADUs and SB 9 Homes as Condos

State law (AB 1033) lets each city decide whether owners may sell an ADU separately from the main home. San Jose opted in through Part 2.76 of its code (sections 20.80.181 to 20.80.185, Ordinance 31095): "This Part implements Government Code Section 66342, herein referred to as Assembly Bill 1033 (AB 1033)." Owners can convert existing or new ADUs into condominiums through a parcel map.

The same map can include SB 9 homes: "the parcel map approved pursuant with this Section may also include the subdivision of up to two (2) primary dwelling units, in conformance with Part 8, Senate Bill 9 implementation, into condominiums." Every lienholder, such as your mortgage lender, must consent, and a lender may refuse. Ask your lender before you design for separate sale.

Fees and Loan Limits

State fee rules apply in San Jose: no impact fees on an ADU of 750 square feet or less, and a 2026 maximum Level I school fee of $5.38 per square foot of assessable space, which a district may set lower. Ask the city for its current local fee schedule; state law requires cities to post one online. See the impact fees page.

The Federal Housing Finance Agency's 2026 conforming loan limits for Santa Clara County are $1,249,125 for one unit, $1,599,375 for two, $1,933,200 for three and $2,402,625 for four.

Where to Go Next

Related on VanPlex: California SB 9 in the global multiplex zoning comparison and the duplex to fourplex guide.

Frequently Asked Questions

Official sources (checked October 2026)