The three faces of factory-built

Modular - Two or more house sections are completely assembled in the factory. Then the sections are trucked to the site and hoisted onto the foundation and joined. Modulars make up about 11 percent of all factory-built homes.

Panelized - The house is built and shipped in pieces: Each wall, floor and roof section is trucked to the site and then assembled. Some 18 percent of manufactured housing is panelized; production has dropped off in recent years.

Mobile - Now called ''manufactured homes,'' many are never moved after being placed on a site. They make up about 69 percent of all factory-built houses. Usually one complete unit, averaging $20,000, includes draperies, carpets, furniture, and appliances. The market for multiple-unit mobiles is growing.