Skip to Main Content
Contact Us Search
Organization Title

Program History

In 1957, an industry group known as the Trailer Coach Association (TCA) representing "trailer" manufacturers sponsored legislation that made it unlawful after September 1, 1958 for any person to sell or offer for sale within California, any trailer not in compliance with construction regulations of the Department of Industrial Relations, Division of Housing. This was the first by any state to regulate trailer (also known as "trailer coaches") construction and the predecessor to today's modern codes regulating mobilehome, manufactured home, commercial modular, special purpose commercial modular, and recreational vehicle construction.

In the beginning, all types of trailers were entitled "trailer coaches" in the law and regulations. As time passed and manufacturers began manufacturing specific types of units for different markets and uses, the names "mobilehome" and "commercial modular" emerged. In 1979, the name "special purpose commercial modular" emerged in order to separate smaller vehicular type commercial modulars with a high degree of mobility from those which are larger transportable structures generally intended for extended or permanent installation.

In 1976, the U.S. Department of Housing and Urban Development (HUD) adopted preemptive federal regulations for the construction of mobilehomes (now manufactured homes). The HUD definition for "mobilehome" was essentially the same as California's existing definition except that it applied only to single-family dwellings while a California mobilehome could consist of two dwelling units. In 1980 the U.S. Congress legislated a change in terminology from "mobilehome" to "manufactured home," that was to take effect on January 1, 1981. In 1982, HUD changed the usage of "mobilehome" to "manufactured home."

The following may help in understanding the types of units subject to the Department's manufactured housing programs:

Manufactured Homes (includes mobilehomes) are "single-family dwellings" transportable in one or more sections constructed to a federally preemptive standard. Legal definition contained in Health and Safety Code Section 18007.

Multifamily Manufactured Homes are one or two family dwellings transportable in one or more sections built to Department regulations designed to contain no more than two dwelling units. Legal definition contained in Health and Safety Code Section 18008.7.

Recreational Vehicles are vehicles designed for recreational, seasonal, or emergency occupancy and are built to nationally recognized recreational vehicle standards. Effective January 1, 1999, chapter 293 of the 1998 Statutes (AB 1984, Miller) repealed the Department's authority to review and approve plans, conduct inspections, and issue insignia of approval to indicate compliance with applicable standards. The remaining authority is to investigate possible violations by a manufacturer "at the factory." Park trailers are included within the definition of a recreational vehicle. Legal definition contained in Health and Safety Code Section 18010.

Commercial Modulars are transportable structures (not vehicles) greater than 8 ft. 6 in. wide or 40 feet long requiring a permit to be moved on the highways, which are designed for human occupancy for industrial, professional, or commercial purposes, and are built utilizing nationally recognized "model" building codes adopted by reference into Department regulations. Legal definition contained in Health and Safety Code Section 18001.8.

Special Purpose Commercial Modulars are vehicles with or without motive power which may be moved on the highways without a permit, designed for human occupancy for industrial, professional, or commercial purposes without structural standards but with plumbing, electrical, and mechanical standards. A special purpose commercial modular includes a mobile food preparation unit. Legal definition contained in Health and Safety Code Section 18012.5.

Manufactured homes have been built to federally preemptive construction standards since June 15, 1976. The Department of Housing and Community Development was once the exclusive HUD approved inspection agency for new manufactured home construction, but since July 1, 1986, that responsibility has been shared with HUD-approved private inspection agencies. The Department also provided design approval service for "manufactured homes" until January 1, 1987. All such design review is now provided by private design approval agencies approved by HUD for all manufactured housing produced in California.

On April 1, 1989, the design approval and in-plant inspection of mobilehomes, commercial modulars, special purpose commercial modulars, and recreational vehicles to assure compliance with state law and Department regulations was delegated to Department approved private Quality Assurance Agencies (inspection) and Design Approval Agencies (design approval).

The Department remains active in the promulgation of regulations for mobilehome, commercial modular, and special purpose commercial modular construction and monitoring the performance of Department-approved Quality Assurance and Design Approval Agencies. The Department also, as applicable, approves designs and performs inspections when the construction, fire-life safety, electrical, plumbing or mechanical systems are altered from the originally approved design.