What SB 9 actually allows
SB 9, effective January 1, 2022, requires cities to ministerially approve — meaning no hearing, no discretionary review, no CEQA — up to two units on a lot currently zoned single-family, and separately allows splitting an eligible lot into two roughly equal parcels of at least 1,200 square feet each. Stack both mechanisms and a single-family lot can, in theory, become up to four units. This is statewide law and applies across every SGV city zoned for single-family residential, subject to the eligibility conditions below.
Read it as amended — SB 450 changed the deal in 2024
A lot of what's written about SB 9 online describes the law as it stood at passage, before a 2024 cleanup bill, SB 450, changed several of the operating rules effective January 1, 2025. If you're reading an older source, some of it is out of date. Under SB 450:
- A complete application must be approved or denied within 60 days, or it's deemed approved.
- A denial must come with written comments identifying every defect and how to cure it — a city can't just say no.
- Cities can't apply objective zoning, subdivision, or design standards that don't apply uniformly across the underlying zone, unless the SB 9-specific standards are more permissive.
- Lot-split standards are limited to the design or improvements of the parcel — a city can no longer deny a lot split for "impact on the physical environment."
- SB 450 also removed SB 9's original bar on demolishing more than 25% of a home's existing exterior walls, which changes the renovate-vs-rebuild math on an existing house.
SB 450 also rewrote SB 9's own legislative findings to state more broadly that increasing housing supply — not just affordable housing specifically — is a matter of statewide concern. That rewrite was a direct response to an April 2024 trial court ruling that had struck SB 9 down as applied to several charter cities, on the theory that the original findings were too narrowly tied to affordability to override local charter control.
Eligibility conditions that still apply
- No demolition or alteration of deed-restricted affordable housing, or housing a tenant has occupied within the last three years.
- The parcel can't be one where the owner exercised Ellis Act eviction rights within the prior 15 years.
- Not in a historic district, on the State Historic Resources Inventory, or a locally designated landmark.
- Any resulting rental must be for terms longer than 30 days — no short-term rentals.
What SB 9 doesn't touch
It doesn't waive impact fees, school fees, or utility connection charges — those still apply under the state's separate Mitigation Fee Act framework and are frequently the real cost constraint on a small SB 9 project, not the entitlement process itself. It also doesn't create any new financial subsidy; it removes a procedural barrier, not a cost.
Both sides of it
For an SGV single-family owner or a small investor, SB 9 is a real by-right option — duplex, lot split, or both — with a fast, predictable timeline now that the 60-day deemed-approved clock is in effect, and denials that have to come with a fixable reason. For neighbors and cities that would prefer to control density through the normal hearing process, SB 9 removes that lever for qualifying projects: no public hearing, no discretionary findings, and narrower grounds to say no than existed before SB 450.