Pioneer Prefabricafed House Passes the Test of Time

The granddaddy of the prefabricated house industry got a physical examination on its 25th birthday recently and was pronounced in excellent health.

The patriarch is, of course, a pioneer prefabricated house designed and built of wood at the U.S. Forest Products Laboratory in Madison, Wisconsin, in 1937 and since then widely used by industry as an engineering prototype for America's factory-built homes.

Throughout the quarter,century of its existence on the Laboratory grounds, the house has been in use for offices. Towered over by the five-story main building and other structures. it looks rather like a flattopped suburban "contemporary" nestled among Manhattan's sky-scrapers.

But the 25 years through which it has withstood Wisconsin's rugged climate have proven its durability as no laboratory test could. And so Laboratory research engi. neers decided to celebrate its silver anniversary by removing vital parts and submitting them to various tests.

The parts were two wall panels that could be slipped out of place by removing a few screws and sawins ofi an inch or so of the inner edge.

Supervising the operation was Otto C. Heyer, housing engineer who aided in the planning and construction 25 years ago. Like a doting relative, he hovered over every phase of the operation and examined the panels inch by inch for signs of aging and decrepitude. He found practically none.

In fact, when one half-panel was placed in a testing machine and loaded in bending-the engineers called it "quarter-point loading"-it exceeded all expectations in strength and stiffness. Two and a half tons of load were necessary before it gave way -many times the design load normally required for house walls.

When built, the house was unique in that it represented the first truly engineered structure of its type ever built in this country. The engineers who designed it-the late John Newlin and George W. Trayer, who has since retiredincorporated a radically new principle of design. They called it the o'stressed-skin" principle.

Essentially, explains Heyer, this principle means that you make the skin of the house carry its part of the load, not putting the whole job on the framework. In conventionally built houses, the "skins" of sheathing, siding, flooring, and roofing are expected only to enclose the house. The framework of joists, studs, and rafters supports all loads including the weight of the structure itself, furniture, appliance, and occupants.

The late Eleanor Roosevelt, then First Lady of the United States, visited the house in i937 just after its completion and exclaimed over its practicality as a new concept for low-cost housing. Many industry leaders have since agreed with her, adapting its stressed-skin principle to factory methods of making floors, walls, and roofs of houses as well as dramatic new structural designs, such as folded-plate roofs, space planes, and arch forms.