AB 1815: Factory-built housing: building standards and local requirements.
This bill aims to regulate building standards for factory-built housing in California. It prohibits cities, counties, and city-counties from imposing standards exceeding the state minimum building standards, as long as a certain percentage of the project's costs are spent on factory-built housing that meets the department of housing and community development's approval. The bill also expands the scope of a crime and adds to the duties of local officials, making it a state-mandated local program. The bill applies to all cities, including charter cities, and does not require reimbursement for certain costs.
| Sep. 29, 2026 | Chaptered by Secretary of State - Chapter 782, Statutes of 2026. |
| Sep. 29, 2026 | Approved by the Governor. |
| Sep. 10, 2026 | Enrolled and presented to the Governor at 3 p.m. |
| Aug. 30, 2026 | Senate amendments concurred in. To Engrossing and Enrolling. (Ayes 74. Noes 0. Page 6868.). |
| Aug. 28, 2026 | In Assembly. Concurrence in Senate amendments pending. |
LEGISLATIVE COUNSEL'S DIGEST
The people of the State of California do enact as follows:
SECTION 1.
Section 19966.1 is added to the Health and Safety Code, to read:19966.1.
“Building assembly” means assembled construction materials, components, subsystems, subassemblies, or other systems designed for use in, or as part of, factory-built housing, which may include structural, electrical, mechanical, plumbing, and fire protection systems and other systems affecting health and safety. However, “building assembly” does not include appliances or equipment, such as heaters, stoves, refrigerators, or air conditioners, which have been listed and labeled by an approved testing and listing agency.SEC. 2.
Section 19967 of the Health and Safety Code is amended to read:19967.
“Building component” means any subsystem, subassembly, or other system designed for use in, or as part of, a structure, which may include structural, electrical, mechanical, plumbing, and fire protection systems and other systems affecting health and safety that bears the insignia of the department and 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. However, “building component” does not include appliances or equipment, such as heaters, stoves, refrigerators, or air conditioners, which have been listed and labeled by an approved testing and listing agency.SEC. 3.
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 housing plans and specifications.SEC. 4.
Section 19971 of the Health and Safety Code is amended to read:19971.
“Factory-built housing” means a residential building, dwelling unit, as defined in Section 19970, or an individual dwelling room or combination of rooms thereof, building component, as defined in Section 19967, building assembly, as defined in Section 19966.1, or building system, as defined in Section 19967.1 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 part, including units designed for use as part of an institution for resident or patient care, 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. Factory-built housing does not include a manufactured home, as defined in Section 18007, 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. 5.
Section 19971.1 is added to the Health and Safety Code, to read:19971.1.
“Factory-built housing structure” means a residential building where at least two-thirds of the new or converted square footage is designated for residential use and in which at least 30 percent of the residential use portion of the building is built using factory-built housing, as defined in Section 19971, and calculated based on the building’s area, volume, or size, as determined by the licensed design professional responsible for the project and subject to concurrence by the department or design approval agency.SEC. 6.
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. 7.
Section 19981 of the Health and Safety Code is amended to read:19981.
(a) All factory-built housing bearing an insignia of approval pursuant to Section 19980 shall be deemed to comply with the requirements of all ordinances or regulations enacted by any city, city and county, county, or district which may be applicable to the construction of housing. No city, city and county, county, or district shall require submittal of plans for any factory-built housing manufactured, or to be manufactured, pursuant to this part for the purpose of determining compliance with this part or the regulations promulgated thereunder, or for determining compliance with any local construction requirement, except as provided in Sections 19993 and 19993.1.SEC. 8.
Section 19993 of the Health and Safety Code is amended to read:19993.
(a) Local use zone requirements, local snow load requirements, local wind pressure requirements, local fire zones, building setback, side and rear yard requirements, site development and property line requirements, as well as the review and regulation of architectural and aesthetic requirements are hereby specifically and entirely reserved to local jurisdictions notwithstanding any requirement of this part.SEC. 9.
Section 19993.1 is added to the Health and Safety Code, to read:19993.1.
(a) Notwithstanding Section 19993 and except as otherwise provided in this section, a city, county, city and county, or district shall not impose or enforce local building standards applicable to a factory-built housing structure that exceeds or differs from the applicable mandatory standards contained in the California Building Standards Code.SEC. 10.
Section 25227 of the Health and Safety Code is amended to read:25227.
A person shall not engage in any of the following on land that is subject to a recorded land use restriction pursuant to former Section 25229, 25230, or 25398.7, as those sections read on January 1, 2012, or pursuant to Section 25202.5, 25221, or 79055, unless the person obtains a specific approval in writing from the department for the land use on the land in question:SEC. 11.
Section 6012.7 of the Revenue and Taxation Code is amended to read:6012.7.
(a) For the purposes of this part, “gross receipts” from the sale of factory-built housing, and the “sales price” of factory-built housing, sold or stored, used, or otherwise consumed in this state shall be 40 percent of the sales price of the factory-built housing to the consumer.SEC. 12.
Section 321 of the Vehicle Code is amended to read:321.
“Factory-built housing” means the same as defined in Section 19971 of the Health and Safety Code. As used in this code, factory-built housing is a trailer coach which is in excess of eight feet in width or in excess of 40 feet in length.SEC. 13.
Section 387 of the Vehicle Code is amended to read:387.
“Manufactured home” is a manufactured home, as defined in Section 18007 of the Health and Safety Code, a commercial coach, as defined in Section 18001.8 of the Health and Safety Code, a mobilehome, as defined in Section 18008 of the Health and Safety Code, factory-built housing, as defined in Section 19971 of the Health and Safety Code, and a trailer coach which is in excess of 102 inches in width, or in excess of 40 feet in overall length measured from the foremost point of the trailer hitch to the rear extremity of the trailer. Manufactured home does not include a recreational vehicle, as defined in Section 18010 of the Health and Safety Code.SEC. 14.
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 5 of Article XI of the California Constitution. Therefore, Section 9 of this act adding Section 19993.1 to the Health and Safety Code applies to all cities, including charter cities.SEC. 15.
No reimbursement is required by this act pursuant to Section 6 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 Section 17556 of the Government Code, or changes the definition of a crime within the meaning of Section 6 of Article XIII B of the California Constitution.