Builder Matt Belcher often uses soy-based spray foam to insulate the attics of homes he builds in St. Louis. It costs about the same, installs about the same, and insulates about the same as spray foam insulation made entirely of petrochemicals. But there are two big differences. Unlike petroleum products, soybeans are a U.S.-produced renewable resource, and the spray foam he uses doesn't emit as much toxic gas as traditional spray foam insulation.

“So I prefer the soy-based product,” says Belcher, whose company Belcher Homes uses many “green” materials in its homes to set it apart from the competition.

Spurred by science, increased costs of petroleum, and a growing “green building” consciousness, soy-based building materials are a trend with traction. How much is not clear because the percentage of soy products funneled into building materials isn't tracked, says Mike Erker, bioproducts development director, for the United Soybean Board (USB). “It's growing very rapidly.”

SOY MANY CHOICES: Soybeans grown in U.S. fields are quickly becoming ingredients in many products, from foam insulation to carpet backing. In addition to spray foam insulation, soybean derivatives also are being used for rigid foam board insulation, adhesive that locks carpet yarns into the backing, roof coatings, and additives in paints and stains. Some promising research also shows that soy meal can be turned into a serviceable adhesive for gluing together wood fibers to form wood composites, such as plywood, OSB, and MDF.

Many of the new uses for soybeans were discovered by researchers backed by the USB, which has been looking to develop new uses for the bean beyond food. While the U.S. production of soybeans has remained constant over the years, as has the price, South American countries have become big soybean growers as well. “You always have got to look for new opportunities,” says Erker. “At this time, all kinds of companies, from the Dow's and the DuPont's and Ford Motor Co., are working on putting [soy-based] products in the marketplace. … Their costs have gone up because petroleum has gone up tremendously. But soybean oil has stayed relatively stable for years.”

Soybeans are typically broken down into two components–oil and a meal. Traditionally, demand was greater for the meal, a protein used for human and animal food. That sparked scientists to search for more uses for the oil. Their first step was to resurrect some old uses.

In the early part of the last century, soybean oil was used to create some of the first plastics. Henry Ford put a soy-derived plastic trunk on some of his early model cars. And before World War II, soy was used as the glue for plywood. But the lowly bean was soon replaced with petroleum products.

While it's hard to imagine that the oil from a bean and petroleum have much in common, they both produce polyols that can be turned into polyurethane, a central ingredient for insulation and a thousand other products. And, unlike ethanol from corn, it has required no subsidies to make it economically viable, says Mike Muccio, CEO of BioBased Systems and BioBased Technologies, Rogers, Ark.–based companies that produce polyols from soybeans as well as manufacture polyol-based products. “That's why we think the future is so bright. It's almost like a diamond in the rough. It's something that doesn't need to be subsidized to work today.”

Sales of soy-based insulation produced by BioBased Insulation, a sister company, increased 24 percent in 2006 over 2005, says Cameron Bowman, the company's marketing manager. “The demand for our product is increasing in every region of the country.” The company has more than 100 distributors of the product around the world.

Bowman says the company's soy-based insulation is priced competitively with other spray insulations. “Because soy bean prices are so stable, it allows us to keep our price more stable,” he says.