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ADU answers
VerifiedRulesReviewed 2026-04-24

SB 9 vs ADU: what homeowners should know

The plain-English difference between an ADU path and California SB 9, and why San Jose homeowners should not mix them up.

Direct answer

The short version

Verified

An ADU is an accessory unit on a property. SB 9 is a separate California housing law path for certain two-unit developments and urban lot splits. They can affect strategy, but they are not the same decision.

San Jose scope

Where this applies

Modeled

For San Jose homeowners, ADUOS treats SB 9 as a separate planning question, not the default ADU answer. Eligibility depends on the parcel and current law.

ADUOS checks

What we check first

  • Whether the homeowner is asking for an ADU or a split/development pathModeled
  • Whether SB 9 should be screened as a separate possibilityVerified
  • Whether the parcel has obvious disqualifying uncertaintyNeeds review
  • Whether ADU and SB 9 assumptions are being mixed incorrectlyModeled
  • Whether the next step should be legal or planning reviewNeeds review

What could change this

The answer can move

  • Parcel eligibilityNeeds review
  • Hazard, historic, or other state-law exclusionsNeeds review
  • Local objective standardsNeeds review
  • A land-use professional's reviewNeeds review

Source notes

Why the label matters

Needs review

SB 9 discussion must use current HCD guidance and stay cautious. Do not present SB 9 as a guaranteed path from a shallow address screen.

FAQ

Common follow-ups

Is SB 9 an ADU law?
Verified

No. It is a separate state housing path. ADUs and SB 9 can both matter, but they answer different questions.

Should I use SB 9 instead of an ADU?
Needs review

That depends on property eligibility, goals, financing, and legal review. ADUOS should screen it cautiously, not promise it.