The factory-built house, which has been talked about for years as the way to cut home building costs, is beginning to take root in American communities. But even though some of the largest companies in the industry are located in California; the state is not leading the way in this development.

Manufacturers say there are several obstacles between their production lines and any large-scale development of housing tracts with homes built primarily in a factory and bolted together at the home site.

Residents of established neighborhoods are suspicious of any kind of low-cost housing nearby, developers say -- especially if it seems too closely related to mobile homes and their lingering association with transient trailer parks.

Financing has at times been difficult, although lenders are looking more favorably on the factory product now, and even mobile homes can be bought on long-term, mortgage-type loans.

Some manufacturers say they lack experience in being community developers and that they need to work with established developers to find solutions to the other problems too. The industry claims it can produce a house for several dollars per square foot less than a conventional "stick" builder who puts up a house entirely at the site. But that doesn't include the cost of land, or of building a foundation and setting the factory house up on its lot.

Where factory building gains a decisive edge over on-site construction is in the Midwest and Southeast, where severe weather can cause costly holdups in site building; and in rural areas, where expert subcontractors and skilled craftsmen may not be available at the building site.

In Southern California, where the weather seldom interferes with construction and there's no shortage of skilled help, developers find it easier and simpler to stick with tried and true building methods.

"We would be among the first to go into a method that was less expensive and as flexible (as conventional on-site building)," says Michael I. Keston, president of the Larwin Group Inc., a community development company. "We don't see it today. I want to watch the other guys try it, and then if it works I'll come in."

Larwin has experimented with "panelized" sections made in a factory to be assembled on site, Keston says, but costs were higher than for traditional methods, and lenders refused mortgage loans for those homes.

"We'll try it again this year for a couple of houses, and see how it goes," he adds.

In the long run, Keston says he expects factory building techniques will continue to be introduced gradually at the building site. Many items such as cabinets and door frames are being delivered to building sites now as pre-fabricated parts of a house, and drywall panels have largely replaced lath and plaster. If lumber costs keep rising., Keston says, today's two-by-four construction might be replaced by metal framing and other systems which lend themselves more to factory assembly than on-site building.

Some developers look askance at the idea of factory construction because of the failures of some experiments in the early 1970s, says James W. Smith, director of planning and development at Avco Community Developers Inc., of Laguna Niguel, Calif.

"A lot of people had financial problems with what should have worked, in theory, but turned out to be too troublesome," Smith said. "Life's too short for that kind of headache."

Those were the days of the federal Operation Breakthrough, launched in 1969 amid visions of home modules being neatly dropped into place by giant cranes and helicopters. Builders were encouraged to experiment with new materials and construction methods, hoping to find the key to cheaper, faster building.

George Romney, then secretary of the Department of Housing and Urban Development, predicted that by 1980 two-thirds of all housing built in this country would be basically factory-made. Some builders will go along with that prediction -- but instead of a dramatic breakthrough which never came, they expect a gradual evolution.