More and more people are moving into houses hot off the factory assembly line

A young family moves into a St. Louis suburb. The new house looks just like a lot of other houses around: sparkling new, attractive, and obviously well designed.

Behind the scenes, however, there is something special about this particular new home. The house wasn't constructed "board by board" on its site in the conventional way; it was put together in a large manufacturing plant. The home's major components and systems were factory produced and then trucked to the site for final assembly.

The St. Louis family didn't mind in the least moving into a house that a few weeks before had been on a factory assembly line. The more they learned about it, in fact, the more they liked the idea.

What it meant was a much higher level of construction efficiency and cost effectiveness. In other words, the system made it possible for the family to acquire more house for its dollar, while a more favorable financing package was more readily available as well.

The St. Louis family scenario is fictional, but it describes a typical situation in the current market where families are more inclined than ever before to accept, and sometimes seek out, an opportunity to buy a manufactured home.

Manufactured housing has been slow to emerge as a major factor in the housing market. Now, because of new trends and developments, the time may be ripe for a big step forward in this type of housing production.

This year about 158,000 full-sized manufactured homes (not mobiles) will be produced, according to Richard M. Morrison, executive director of the Manufactured Home Council of the National Association of Home Builders.

"That's not a huge volume at this point," he admits, "but it's increasing rapidly. Within 15 years half of the total new housing supply will probably be produced by automated construction systems."

Mr. Morrison expects that the industry will grow dramatically when some of the current growth-stunting problems are resolved. One of those problems is the inconsistency of local and state building codes. Also, transportation laws define the size and weight of housing modules or panels that can be transported by truck, and these laws vary from state to state.

When these and other problems are solved, people associated with the industry say it will grow and expand tremendously. As a result, the higher production and improved manufacturing techniques would be expected to bring prices down for individual units.

"There's a big market out there for manufactured homes," Mr. Morrison assets. "It's not only home buyers in this country. We have recently had a parade of foreigners contacting our office, expressing interest in these automated building systems and their products. We are just now beginning to see the real potential of this new industry."

New materials and technologies are rapidly enhancing the potential of factory-built housing. And even more sophisticated systems are on the way, including the use of house-construction robots in the manufacturing process.

The key factors behind the idea are:

* Lower labor costs.

* New computer technology that makes it possible for manufacturing equipment and operations to function more efficiently.

* Better custom-matching opportunities. Individual buyers, for example, can pick optional colors, materials, and components quickly and easily. It's actually as easy as buying a new car.

* Fast turnaround time from order to turnkey readiness.

While prices of comparable new homes (manufactured vs. custom built) do not reflect a great difference at this point, that difference is widening, with prices for manufactured houses going down. In a few years it will be significant enough to attract a substantial share of home buyers to this type of unit.

The concept that is most effective in reducing the unit cost of manufactured housing is the mass production of single-home plans, without offering the buyer a variety of style options. That approach is being implemented by an increasing number of house-manufacturing firms.

"We focus in on a single idea we have tested and proven to be successful and popular in the market-place, says David Baker, executive vice-president of Cardinal Industries, largest modular-home manufacturer in the United States.

"We standardize that product, such as in the automobile design and manufacturing industry. That way, we can produce the best possible modular home and pass along resulting economies to the buyer."

Mr. Baker also notes that more research and development is needed in the house-manufacturing process to fully realize the potential of the industry.

Briefly, four basic kinds of manufactured houses exist:

* Precut home. All lumber is pre-cut in the factory and shipped to the building site for assembly.

* Panelized home. This unit is prefabricated in the factory and shipped to the building site as wall panels. This is now the most popular and versatile form of manufactured housing.

* Modular or sectional home. The modular home is about 95 percent complete when it leaves the factory. Two almost-complete halves are usually shipped to the site on a lowboy trailer-truck. The concept is also used extensively for small apartment and condominium buildings as well as motels and commercial structures.

* Mobile homes. These are the familiar single-wide and double-wide units seen in mobile-home parks all over the country. The units are usually built to conform to a building code set by the Department of Housing and Urban Development.

Many of the new breed of manufactured homes are just as attractive, comfortable, and durable as any stick-built home.