Existing law, the California Building Standards Law, establishes the California Building Standards Commission within the Government Operations Agency. Existing law requires the commission to approve and adopt building standards and to codify those standards in the California Building Standards Code.
Existing law, the California Factory-Built Housing Law, generally regulates the design, manufacture, and installation of factory-built housing, as defined and specified. That law specifically and entirely reserves to local jurisdictions certain local requirements, including local use zone requirements, snow load requirements, and wind pressure requirements. That law provides that any person who violates any of these provisions and other specified law is guilty of a misdemeanor, as specified.
This bill would instead reserve to local jurisdictions local use zone requirements, local design standard requirements, local flood resistant control standards, and local wildfire safety building requirements, as provided. The bill would provide that the Legislature finds and declares that the California Building Standards Code addresses regional variations in snow load and wind pressure, as specified.
This bill also would prohibit a city, county, or city and county from imposing or enforcing building standards that exceed the state minimum building standards in the California Building Standards Code on a factory-built housing construction project. The bill would clarify that this provision does not apply to structures of a development project that are not factory-built housing.
This bill would revise and recast definitions of key terms for purposes of the California Factory-Built Housing Law. In this regard, the bill would generally define "factory-built housing" to mean a residential building with a ratio of the cost of factory-built components to the total direct hard costs for the scope of construction work within the footprint of a structure that is at least 15%, as specified, where at least 23 of the new or converted square footage is designated for residential use. By adding to the duties of local officials, and expanding the scope of a crime, this bill would impose a state-mandated local program.
The bill would include findings that changes proposed by this bill address a matter of statewide concern rather than a municipal affair and, therefore, apply to all cities, including charter cities.
The California Constitution requires the state to reimburse local agencies and school districts for certain costs mandated by the state. Statutory provisions establish procedures for making that reimbursement.
This bill would provide that no reimbursement is required by this act for specified reasons.

Statutes affected:
AB 1815: 19985 HSC
02/10/26 - Introduced: 19985 HSC
03/19/26 - Amended Assembly: 19993 HSC, 19993 HSC, 19985 HSC
04/27/26 - Amended Assembly: 19993 HSC
06/22/26 - Amended Senate: 19969.3 HSC, 19969.3 HSC, 19971 HSC, 19971 HSC, 19972 HSC, 19972 HSC, 19975.1 HSC, 19975.1 HSC, 19976.05 HSC, 19976.05 HSC, 19993 HSC
07/02/26 - Amended Senate: 19969.3 HSC, 19971 HSC, 19972 HSC, 19975.1 HSC, 19976.05 HSC, 19993 HSC
AB1815: 19993 HSC, 19993 HSC, 19985 HSC