California was the first governmental entity to regulate manufactured homes by the Department's implementing 1957 legislation on September 1, 1958. The initial authority and regulations pertained to the plumbing, heat producing and electrical equipment and installations in manufactured homes. Not until September 15, 1971 did the Department have the authority and regulations for the structural and fire-safety components of the manufactured home. Two of the primary components of the structural regulations were a design requirement to resist wind loads and a requirement that manufactured homes be accompanied by Department approved installation instructions. At that time California Law prohibited the installation of manufactured homes in any permanent manner, such as on a foundation system.
In order for manufacturers of manufactured homes to meet the minimum structural requirements for wind loads, all manufacturer's installation instructions required that the manufactured home had to be 'tied down." Installations of these manufactured homes were not subject to regulation and few homes were ever installed in accordance with the manufacturers installation instructions, much less with the tiedown devices necessary to meet wind loads. Manufactured homes continued to be installed as they had in the past, on some sort of pier system that met only vertical loads, even though the post-1971 homes had the design capacity to resist wind loads when properly installed in accordance with the manufacturers installation instructions.
In 1973, the Legislature added HSC 18613, providing authority in the Mobilehome Parks Act for regulating the installation of manufactured homes. The Department implemented HSC 18613 on July 1, 1974 following extensive hearings on the related regulations held by the then Commission on Housing and Community Development. The Department had proposed in these regulations that, among other things, manufactured homes were required to be installed in accordance with the manufacturers installation instructions. That proposal meant that manufactured homes would have to be installed with tiedown devices to meet design for resistance to wind loads. In these 1974 hearings the Commission on Housing and Community Development heard considerable opposition to the requirements for tiedowns from manufactured home owners and their representatives. This opposition focused on the increased cost of manufactured home installations, estimated to be between $750 and $1,500. The Department argued for the tiedown devices on the basis of achieving the safety provided in the manufacturer's design of the manufactured home to resist more than just the forces of gravity. The Commission on Housing and Community Development, sensitive to the substantial opposition, adopted requirements for tiedown devices only on singlewide manufactured homes installed in areas of the State with documented wind loads in excess of 15 pounds per square foot. Since the majority of California is within wind load areas designated as 15 pounds per square foot and the great majority of manufactured homes sold in California are multiwides, the heavily opposed tiedown devices were essentially not required.
The Department tried again in 1978 to require the installation of tiedown devices as necessary to meet the manufacturers installation instructions and design of the manufactured homes to resist wind loads. The 1978 meeting of the Commission on Housing and Community Development on the Departments proposal to require tiedowns was a repeat of 1974 hearings with mail bags full of written opposition to the Departments proposal being emptied in front of Commissioners on the floor of the hearing room. The Commission on Housing and Community Development did not adopt the Departments proposed requirements for tiedown devices. Manufactured homes continue to be installed only to resist the vertical forces of gravity although designed and recommended by the manufacturers to be installed to also resist wind loads.
In 1979, the Legislature removed the statutory prohibition against the permanent installation of manufactured homes and added HSC 18551 permitting the installation of manufactured homes on foundation systems, effective January 1, 1980. Regulations adopted by the Department for the installation of manufactured homes on foundation systems parallel requirements for conventional site-built housing and therefore require both resistance to wind and seismic loads.
In response to displacement of manufactured homes from pier support systems by seismic disturbances a growing number of small manufacturers began to construct and market devices known as earthquake bracing systems in the late 1970's. These systems were marketed as earthquake safety devices to prevent the manufactured home from falling to the ground in the event the manufactured home was displaced from its pier support system by an earthquake. As these systems became more popular, the Legislature added HSC 18613.5 in 1981 requiring the Department to regulate the design and construction of these systems, known as Earthquake Resistant Bracing Systems (ERBS) and added HSC 18613.7 in 1989 to regulate their installation.
