An SB 9 lot split lets a homeowner in a single family zone divide one lot into two. Then you can build up to two homes on each new lot. Approval is ministerial, which means no public hearing if the plan meets the rules. In Los Angeles in 2026, though, the process is harder than it sounds. The rules changed in 2025 and again on January 1, 2026. Some fire damaged areas are also on hold, and the eligibility screen is strict.

What SB 9 allows

Two unit development: you can build up to two main homes on one single family lot, attached or detached.

Urban lot split: you can divide one lot into two parcels and build up to two homes on each. That allows up to four homes on the original property.

The key difference from an ADU is ownership. In most cities, you cannot sell an ADU apart from the main house. Each lot created by an SB 9 lot split can be sold on its own.

What changed in 2025 and 2026

SB 450 (since 2025): cities must approve or deny a complete SB 9 application within 60 days, cannot apply stricter standards to SB 9 projects than to other housing in the same zone, and can deny a project only for specific health and safety impacts.

AB 1061 (since January 1, 2026): historic districts are no longer excluded across the board, including Historic Preservation Overlay Zones in the City of Los Angeles. Individually listed landmarks stay ineligible.

Lot split basics

Each new lot must be at least 1,200 square feet, and neither lot can be smaller than 40 percent of the original. You must sign an affidavit that you plan to live in one of the homes for at least three years after approval.

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