On a qualifying single-family lot, 1 lot can legally become 4 addresses. That sentence is true and it is also where most owners get burned, because the word that matters is qualifying. Here is the full 2026 menu state law puts on the table, the gates that decide whether your specific parcel gets any of it, and the 15 checks we run before anyone spends real money on plans.
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Start with what a standard single-family lot in Santa Clara County can hold before any lot split.
That is the legal ceiling. Almost no lot gets the whole menu, and a Terner Center study found only about 5 percent of California single-family parcels actually pencil for SB 9 development. The difference between the ceiling and your lot is decided by the gates below.
The base zoning district is only the first layer. Planned development overlays, urban village boundaries, and design combining districts can add standards or strip eligibility entirely. Two lots on the same street can have different answers.
Parcels mapped in a Very High Fire Hazard Severity Zone are excluded from SB 9 unless the project meets state fire mitigation standards. The foothill edges of San Jose, Saratoga, Los Gatos, and Cupertino carry large mapped zones, and CAL FIRE updated the maps in 2025, so an old answer may be stale.
SB 9 does not apply to parcels in a designated historic district or to listed landmark properties. ADU rules also tighten. A conservation area designation you never knew about can take the split off the table.
A recorded utility or access easement across the parcel can block the new building footprint or leave a rear lot with no legal access. Easements do not show up on Zillow. They show up in the title record, and finding one late is one of the most common ways an approved project dies.
New units need new or upgraded electric service. CPUC Decision 24-09-020 now sets energization targets of 30 business days for a standard connection and 60 business days when distribution upgrades are needed, which gives owners an enforceable clock that did not exist before 2024. Gas is its own line item, and PG&E's SB 1210 disclosure puts the average residential gas hookup at $12,466 (PG&E SB 1210 disclosure, 2025). Many owners go all-electric on the new unit for exactly that reason.
In much of the county the sewer authority is a separate district from the city, with its own permit, its own fee schedule, and its own timeline. West Valley Sanitation District, Cupertino Sanitary District, and the City of San Jose each run their own counters. The city permit does not include this and a missing sewer sign-off freezes final approval.
An ADU of 750 square feet or larger pays school impact fees, and units below that threshold are exempt. The Level 1 fee resets to $5.38 per square foot for residential construction effective January 28, 2026 (State Allocation Board, 2026). On a 1,000 square foot unit that is $5,380 that owners routinely forget to budget.
Every free ClearPath Read starts with the same parcel-level sweep. This is the list.
Any one of these can kill a project. Checks 1 through 10 decide whether you can build. Checks 11 through 15 decide whether you should.
Send your address and we run the sweep. The free Read tells you how many viable paths your parcel has and flags the gate most likely to bite, before you spend a dollar on plans.
Get your free ClearPath ReadYes, SB 9 remains state law in 2026 and Santa Clara County cities are processing SB 9 applications. It allows up to 2 units per lot, and an urban lot split that can put up to 4 units across what was 1 single-family parcel. A court challenge over charter cities has created legal noise, so confirm eligibility for your specific city before spending money.
No. Per HCD guidance, the SB 9 lot split applicant must be an individual, not an LLC, corporation, or partnership. The applicant also signs an affidavit of intent to occupy one unit as a principal residence for 3 years after the split. An LLC-owned lot can still add an ADU or a JADU under state ADU law without any split.
Often yes, but the ADU placement decides it. An SB 9 split requires each new lot to be at least 1,200 square feet and at least 40 percent of the original parcel, and the ADU counts against unit limits after a split. An ADU sited across the future lot line or into required setbacks can block the split, so plan the site before you pour a foundation.
A typical San Jose single-family lot supports 3 dwellings by right in 2026, which is 1 primary home plus 1 ADU plus 1 JADU. A qualifying SB 9 urban lot split can raise that to 4 units across 2 new lots. Overlays, fire hazard zones, historic status, and easements can cut the number for a specific parcel, which is exactly what a parcel-level check confirms.
Sources: Gov. Code 65852.21 and 66411.7 (SB 9), Gov. Code 66314 et seq. (state ADU law), HCD SB 9 guidance on applicant eligibility, CPUC Decision 24-09-020 (energization timelines), PG&E SB 1210 disclosure 2025 (average gas hookup cost), State Allocation Board Level 1 fee effective January 28, 2026, Terner Center for Housing Innovation (SB 9 feasibility). Cost figures outside these citations are typical ranges we see. General information, not legal advice. Whether a specific parcel qualifies depends on its facts and the local jurisdiction.
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