California SB 9 lot split and two homes: what it allows on a lot
SB 9 lot split and two homes is California law, and the official source is at hcd.ca.gov.
In a single family zone the city or county must approve two homes on a lot, a split into two lots, or both, up to four homes, with no hearing and within 60 days. Side and rear setbacks may be no more than 4 feet and parking no more than one space a unit. Charter cities since 2025, historic districts since 2026 where no historic building is changed.
Whether it applies to one lot turns on where the lot is and what it is zoned; the city, county or state office named in the law decides. Mapped areas are approximate. This is a plain reading of public law with its source, not legal advice.
Free, no account. ParcelSheet shows the lot's mapped size, parcel lines and flood zone, and this law on the lot's California sheet.
Other California laws on a lot: State ADU law (Gov. Code 66310 to 66342).