For New Houses, Recycled Metal Framing Can Replace Wood
Photo: Steel Recycling Institute
When Mary and Howard Maynard were building a new home in Connecticut, the design included an 18-foot high wall of glass that spanned nearly the entire east side of the structure. Wood framing would not have been effective. “That vast space had a number of tricky structural implications,” says Howard Maynard, adding that the engineer brought into the project designed a steel frame to hold up the broad expanse. “Steel is a wonderful material,” says the Maynards' architect, Chris Carpiniello of Beinfeld Wagner. “It allows you to support heavier loads with less depth, and it gives you flexibility in designing.”
Steel-framed homes run the gamut from ultra-modern to old-fashioned. Although the interior of the Maynards' home is strikingly contemporary, the exterior looks more like a restored barn. The structure blends into the surrounding landscape almost seamlessly.
“I use steel in a lot of my restoration work,” says April Tome, an architect who specializes in housing for the disabled and elderly. Tome points out that steel comes in “true” dimensions—a foot of steel really is 12 inches. Wood shrinks when it dries, so a two-by-12 is actually 1.5 inches by 11.5 inches. Steel advocates have many other reasons for choosing the material: stability (steel doesn't shrink or expand), cost stability, and the fact that it is inert.
(Unlike wood, steel does not need arsenic-based chemical preservations and it does not offgass, so people with extreme chemical sensitivities are less affected.)
Environmentally-conscious builders have another even more compelling reason for using metal framing: Virtually all the steel produced in the U.S. is recycled. Wood may be a renewable resource, but 60 percent of all the timber harvested in the U.S. is used in home construction, and some of it comes from old-growth forests.
Bill Heenan, president of the Steel Recycling Institute, makes an environmental case. “No matter what kind of steel you use, you can't get virgin steel,” he says, adding that steel framing usually contains 30 percent recycled material. Issues remain, however: A 1994 report in Environmental Building News said that while the steel industry has invested $10 billion to improve energy use and pollution, the process of recycling steel creates significant waste products.
Heenan acknowledges that there are some limitations to using steel for home construction. It works well for framing, but not as a piece-by-piece replacement for 2X4 studs, he says. But Heenan adds that steel is termite-proof and not subject to warping, and can also be easily recycled at the end of a home's useful life.
Another drawback is that steel is more than 400 times more heat-conductive than wood, which can translate into excessive energy use for heating and cooling. “Framing with steel isn't something we endorse because of the thermal performance issue,” says Environmental Building News Editor Nadav Malin. “Building with steel might not be as cost-effective when you take into account the need for exterior insulation.”
Heenan, naturally, disagrees with that. “We say that this is a criticism that has no foundation. It's just like anything else, there are differences,” he says. Adds Carpiniello, “Houses today are so well insulated that a little bit of conductivity from steel doesn't really make that much of a difference.” He says that a bigger problem is that wood shrinks and steel doesn't, which can create snafus when the two materials are used together.
Some experts believe that steel is a better construction material for earthquake- or hurricane-prone areas. Heenan notes that there is an increased use of steel framing in Florida and Louisiana. “They put steel bracing into existing houses to protect against hurricane damage,” Heenan says. “Just go to Homestead, Florida, and look at the homes that were remaining after Hurricane Gloria—those were steel constructions.”
John Bower, author of Healthy House Building, used lightweight steel framing in the construction of his Model Healthy House, “primarily to avoid toxic termiticides, and secondarily to avoid the odors of softwood framing lumbers that can bother some sensitive individuals.” Bower says that more builders would probably use steel framing in homes if they were aware of its existence. “The finished house doesn't look any different than any other house,” he says.
In 1993, a survey by the National Association of Home Builders (NAHB) found that about one percent of new homes were framed with steel. Although the American Iron and Steel Institute established a goal of capturing 25 percent of the housing market by 1998, in 1997 only 50,000 homes were entirely framed with steel. Heenan says the institute's new goal is that, by 2002, 25 percent of new homes will use steel “in some way.”