The State of California regulates the manufacturing of factory-built housing and/or housing components.
The Department of Housing and Community Development (HCD)'s Factory-Built Housing Handbook (PDF) summarizes the state’s approval and inspection processes, describes the role of local jurisdictions, and includes the state laws and regulations that apply to factory-built housing.
Factory-built housing — also known as manufactured housing, off-site construction, prefabricated construction and modular housing — refers to the production of building units or building components in a factory rather than at the housing site.