Despite Grand Plans, Prefabrication Still Hasn't Realized Economies of Scale

The Cellophane House, designed by Kieran & Timberlake Associates of Philadelphia, was one of five full-scale models commissioned by the Museum of Modern Art for its exhibit,
The Cellophane House, designed by Kieran & Timberlake Associates of Philadelphia, was one of five full-scale models commissioned by the Museum of Modern Art for its exhibit, "Home Delivery: Fabricating the Modern Dwelling." (Photos By Katherine Salant)
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By Katherine Salant
Saturday, November 1, 2008

For more than a century, architects and builders have strived toward a prefabricated, industrialized house, one made in a factory so that economies of scale would be realized and the product would be affordable to all home buyers.

Needless to say, this elusive goal has not been reached, but not for lack of effort. For instance, a just-closed exhibit at the Museum of Modern Art in New York City, "Home Delivery: Fabricating the Modern Dwelling," featured 51 projects in an exhibit hall and five full-scale models outside.

The models outside were provocative and intriguing, if not ready for prime time. And only seven of the 51 projects presented inside made it to the production line.

Although it was not addressed in the exhibition, the most probable reason that the factory-made house has never achieved huge market success in America is that no one has developed a cost-effective alternative to the 175-year-old method of wood frame construction used by most U.S. home builders, itself one of the early success stories of the industrial age.

Until the 1830s, most houses in America were built with post and beam framing. All the pieces were hand-hewn and held in place with complex joinery, and home building was a time-consuming, costly process. Around then, however, steam-driven saws that could produce large quantities of accurately sized building lumber and machines that made huge quantities of iron nails began to appear in the larger cities.

An enterprising Chicago building contractor, George Washington Snow, saw the potential for these new products to revolutionize the building industry. He devised a method of framing that was much faster and far less costly. Equally important to a building contractor facing a chronically short supply of skilled workers, the new framing could be built with rudimentary carpentry skills.

As with many innovations, the initial response by experts was derisive -- Chicago carpenters likened the new framing method to a balloon that could easily be blown over in a strong wind. It quickly proved to be as strong as it was easy to make, but the "balloon frame" label stuck.

Balloon framing quickly spread across the country and continues to this day in a modified form. Most home builders use platform framing, but Snow's 2-by-4-inch wood studs and the common steel nail live on as the basic components used to frame the walls. In most cases, the walls are assembled on the site as they were in Snow's day, even by national companies that build thousands of houses a year.

The other components in today's platform building frame are still wood, but in most cases they are manmade, engineered wood products because the old-growth trees from which large framing pieces were cut are no longer available.

In some markets, including the Washington area, the 2-by-4 stud walls sometimes are assembled in factories and hauled to a job site, an approach called panelizing. Nationwide, the portion of houses that were panelized in 2007 was less than 6 percent, said Ed Hudson of the National Association of Home Builders Research Center.

But in recent interviews, a number of builders said that panelizing may become more common as job site waste disposal becomes more costly. The scrap lumber that accumulates when a house is "stick built" is a major component of this waste.

For the same reason, panelizing may also appeal to home builders who participate in green building certification programs because the most popular of these programs give points for minimizing waste.

The U.S. building industry has also developed modular housing, a method of building in a factory an entire conventional wood-framed house in sections, loading each one onto a flatbed trailer, trucking it to a job site and then setting it in place with a crane.

With this type of housing, however, the logistics can be daunting. To deliver the goods, the manufacturer must contend with bridge overpasses that can be a tight squeeze, cars parked on both sides of a narrow street and municipal bus schedules that require dismantling of the hoisting crane every hour to let the bus pass.

In rural areas, where skilled labor is scarce and the site constraints are considerably looser, modular houses have been more widely built, but not in large numbers. Modular houses accounted for about 3 percent of new houses in 2007, and this percentage has been consistent for the past 15 years, said Gopal Ahluwalia, an economist with the National Association of Home Builders.

Several builders suggested that the modular home may come into its own when the housing market rebounds, filling the market niche once held by builders who have recently closed their doors. Richmond land developer Ned Massie, for instance, said he may complete some current projects by engaging a modular firm to take over lots that originally were allocated to small builders.

Katherine Salant can be contacted via her Web site,

Copyright 2008 Katherine Salant

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