What is SB 9 in California?

SB 9 is the California Housing Opportunity and More Efficiency Act, authored by Senator Toni Atkins. It fundamentally changes what's allowed on single-family lots:

1. Urban lot split — any qualifying single-family lot can be split into two lots, each no smaller than 40% of the original and at least 1,200 sqft.
2. Two-unit development — each resulting lot can host up to two units (so up to 4 units total on what was one single-family parcel).
3. Ministerial approval — the city must approve or deny a complete application within 60 days; no CEQA; no discretionary review; no design review outside HPOZ / historic districts.
4. Owner-occupancy — the homeowner must sign an affidavit committing to occupy one of the units for at least 3 years after the split.
5. Exemptions — SB 9 does not apply to lots in very-high fire hazard severity zones without a fire risk mitigation plan, lots in historic districts, and lots that have rented out a unit in the past 3 years (to prevent tenant displacement).

SB 9 economics for LA homeowners:

• Typical lot split application through LADBS: 60-120 days soft costs included ($10,000-$25,000 in surveyor + civil + legal).
• Each resulting parcel can then build an ADU + JADU on top of the base two-unit allowance.
• AB 1033 (2024) additionally allows selling the resulting ADUs separately as condominiums in cities that opt in — LA opted in.
• Combined SB 9 + AB 1033 path: one single-family lot becomes 4 sellable condominium units.

The biggest execution risk is fire severity zone overlap — a non-trivial portion of the LA basin and most of the hillside neighborhoods fall in Very-High FHSZ where SB 9 requires a CAL FIRE risk-mitigation plan that adds $15,000-$50,000 and 3-6 months.

AskBaily's LA ADU + SB 9 scoping checks fire zone overlap before pricing.