Factory-built housing: building standards and local requirements.
AB 1815
California Bills
20250AB__181595AMD INTRODUCED 2026-02-10 AMENDED_ASSEMBLY 2026-03-19 AMENDED_ASSEMBLY 2026-04-27 AMENDED_SENATE 2026-06-22 AMENDED_SENATE 2026-07-02 2025 AB AMD Introduced by Assembly Members Wicks and Quirk-Silva (Coauthors: Assembly Members Caloza, Mark González, Harabedian, and Hoover) LEAD_AUTHOR ASSEMBLY Wicks LEAD_AUTHOR ASSEMBLY Quirk-Silva COAUTHOR ASSEMBLY Caloza COAUTHOR ASSEMBLY Mark González COAUTHOR ASSEMBLY Harabedian COAUTHOR ASSEMBLY Hoover
An act to amend Sections 19969.3, 19971, 19972, 19975.1, 19976.05, and of, and to add Sections 19970.1 and 19971.1 to, the Health and Safety Code, relating to housing. housing Factory-built housing: building standards and local requirements. 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 2 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. MAJORITY NO YES YES NO NO NO NO NO NO NO The people of the State of California do enact as follows:
SECTION
Section 19969.3 of the Health and Safety Code is amended to read: 19969.3. “Design approval agency” means a private organization meeting the requirements specified in regulations of the department to perform evaluation of factory-built components.
SEC.
Section 19970.1 is added to the Health and Safety Code , to read: 19970.1. (a) “Factory-built component” means a volumetric modular unit, panelized system, or assembly that bears the insignia of the department that is either wholly manufactured or is in substantial part manufactured at an offsite location to be wholly or partially assembled onsite in accordance with building standards published in the California Building Standards Code and other regulations adopted by the commission pursuant to
Section 19990, and is manufactured in such a manner that all concealed parts or processes of manufacture cannot be inspected before installation at the building site without disassembly, damage, or destruction of the component. (b) “Factory-built component” does not include a mobilehome, as defined in
Section 18008, a recreational vehicle, as defined in
Section 18010, or a commercial modular, as defined in
Section 18012.5.
SEC. 3.
Section of the Health and Safety Code is amended to read: 19971. “Factory-built housing” means a residential building with a factory-built ratio of at least percent, where at least two-thirds of the new or converted square footage is designated for residential use.
SEC.
Section 19971.1 is added to the Health and Safety Code , to read: 19971.1. (
a) For the purpose of this section, the following
definitions apply: (1) “Cost of factory-built components” means the total cost of manufacturing and applicable sales tax of factory-built components, exclusive of transportation costs. (2) “Cost of vertical construction” means the total direct hard costs, inclusive of labor and materials, for the scope of construction work within the footprint of a structure, including foundations and excluding earthwork and ground improvements.
Direct hard costs do not include a general contractor’s general conditions, general requirements, insurances, overhead, or profit. (3) “General conditions” means the general contractor’s project-specific indirect costs required to manage, supervise, and execute the work. (4) “Insurances” means the general contractor’s general liability, automotive, and workers’ compensation insurances. (5) “Overhead” means the general contractor’s business operating expenses that are not directly attributable to a specific project but are necessary to run the company as a whole. (6) “Profit” means the general contractor’s fee for executing the work. (b) “Factory-built ratio” means the ratio, expressed as a percentage, of the cost of factory-built components to the cost of vertical construction calculated on the basis of a detached structure, as estimated at the time of plan submission to the department, calculated by dividing the cost of factory-built components by the cost of vertical construction, then multiplying by to achieve a percentage.
SEC. 5.
Section of the Health and Safety Code is amended to read: 19972. “First user” means the person, firm, or corporation who initially installs factory-built housing within this state. A person who subsequently purchases factory-built housing is not a first user within the meaning of this definition.
SEC.
Section 19975.1 of the Health and Safety Code is amended to read: 19975.1. “Local inspection agency” means the building department of a city, county, or city and county, which has been certified by the department, and which has assumed responsibility for inspection of in-plant manufacture as provided by
Section 19991.1.
SEC.
Section 19976.05 of the Health and Safety Code is amended to read: 19976.05. “Quality assurance agency” means a private organization meeting the requirements specified in regulations of the department to perform in-plant inspections of the manufacture of factory-built components.
SEC. 8.
Section of the Health and Safety Code is amended to read: 19993. (a)
(1) Local use zone requirements, local design standard requirements, local flood resistant control standards, and local wildfire safety building requirements are hereby specifically and entirely reserved to local jurisdictions notwithstanding any requirement of this part.
(2) Local use zone requirements, local design standard requirements, local flood resistant control standards, and local wildfire safety building requirements imposed on factory-built housing pursuant to the authority granted by this subdivision shall not vary substantially from the requirements imposed on other residential buildings of similar size.
(3) The Legislature finds and declares that
Chapter of the California Building Standards Code robustly addresses regional variations in snow load (Section of Title of the California Code of Regulations) and wind pressure (Section of Title of the California Code of Regulations). (b)
(1) A city, county, or city and county shall not impose or enforce building standards that exceed the state minimum building standards in the California Building Standards Code on a factory-built housing construction project.
(2) If a development project includes factory-built housing and other structures that are not factory-built housing, this subdivision shall apply only to the factory-built housing. (
c) For the purposes of this section, “local flood resistant control standards” means Appendix (
G) of Part of Title of the California Building Code incorporated by a city, county, or city and county.
SEC. 9. The Legislature finds and declares that the provision of adequate housing, in light of the severe shortage of housing at all income levels in this state, is a matter of statewide concern and is not a municipal affair as that term is used in
Section of
Article XI of the California Constitution. Therefore,
Section of this act amending
Section of the Health and Safety Code applies to all cities, including charter cities.
SEC. 10. No reimbursement is required by this act pursuant to
Section of
Article XIII B of the California Constitution because a local agency or school district has the authority to levy service charges, fees, or assessments sufficient to pay for the program or level of service mandated by this act or because costs that may be incurred by a local agency or school district will be incurred because this act creates a new crime or infraction, eliminates a crime or infraction, or changes the penalty for a crime or infraction, within the meaning of