Insulated Concrete Forms
Easily placed over and within standard rebar, lightweight insulated concrete forms create a permanently insulated poured concrete wall above and below grade, speeding cycle time and improving the home's energy performance.
Credit: Portland Cement Association
ICFs are molded from expanded or extruded polystyrene into lightweight, interlocking foam blocks that serve as permanent forms for poured concrete walls. The resulting walls combine the thermal mass and strength of concrete with the energy-saving benefits of integral insulation panels. Sophisticated systems feature metal inserts that act like rebar within the blocks and as vertical, standard on-center nailing strips on both faces of the insulated wall structure.
Of the alternative structural systems trying to enter the mainstream of housing construction, ICFs have made the most headway. The NAHB has tracked the industry's trajectory from a 0.7% market share of above-grade walls for single-family homes in 1997 to a 6.5% share in 2006–equaling more than 103,000 homes last year alone. About three-quarters of the 50-million-plus square feet of ICFs sold annually are used in residential construction.
Once a cottage industry that first took hold as a below-grade system in the northern U.S. and in Canada for its obvious energy-saving benefits, the ICF business is maturing rapidly. There are now about 60 manufacturers distributing ICFs across the country, mostly through regional two-steppers; the International Building Code accepts ICFs among poured-in-place concrete systems, enabling their use nationwide. Big-name suppliers such as Owens Corning (a proprietary ICF system), Dow (sealants), and Simpson Strong-Tie (connectors and bracing), among other logical players, have piggybacked on the system's growing popularity and legitimacy among builders and contractors.
ICFs' most recent popularity is fueled by current events, primarily the Gulf Coast hurricane seasons of 2004 and 2005, as well as nationwide energy price hikes and the green building trend. "We're talking about a system that resists fire and high winds, creates an energy-efficient home, mitigates noise, and is highly durable," says Jim Niehoff, residential promotion manager for the Portland Cement Association in Skokie, Ill., which counts ICFs as the fastest-growing segment of the concrete and masonry systems available for home building.
ICFs also offer production benefits. "Builders love them because they're easier and faster to use [than removable forms] and there's one less sub [insulation] to hire," says Frank Chambers, regional vice president of The Contractor Yard, a Pro-Build dealer in Nashville, Tenn. The forms, he says, are easier and faster for contractors to set in the region's hilly terrain. Combined, the dealer's Knoxville and Cook, Tenn., locations sell about $600,000 worth of ICFs annually. "Those locations carry a good inventory and it turns quickly."
Minnesota custom builder John Vogstrom took to using ICFs eight years ago, specifically to reduce the potential for mold and moisture-related issues that feast in the cavities of framed walls but have no place to fester in solid concrete with integral insulation. Since then, he's further leveraged the energy efficiency of the system to get the most out of geothermal heating, among other green building practices; he also enjoys the ability to create larger window openings than he could with lumber.
Working in a market that was ahead of the current curve for the technology and that currently purchases the most ICFs of any state, Vogstrom has no problem accessing ICFs from several competitive suppliers outside of his lumberyard. "They didn't offer to source it for me, but they couldn't sell it at the same price that I get, anyway," he says. "I still spend a lot of money there, and they're glad to get my business." Short of stocking ICFs, dealers do have an opportunity to support customers who make the switch. Like any system, ICFs have ancillary products, such as snap-together window bucks, tie and drywall anchors, sealants, and a variety of power tools that take up less shelf space than the forms themselves and deliver an attractive margin.
Still, ICFs' 5% to 10% materials-only price premium over CMUs and poured concrete, not considering the labor savings of having integral insulation and permanent forms, is a tough nut to crack with price-sensitive builders. And, ICFs take up a lot of yard space for their weight. "Shipping is a big issue," says Chambers. "The product is so light, but you have to get a tractor-trailer load [to inventory enough volume]."
ICFs also suffer from regional building cultures that are married to stick framing and slabs (as opposed to more masonry-friendly markets in the South and basement-building areas up North) and from a shortage of trained installers to meet demand.
To address the latter issue, the ICF industry is working with the NAHB and its Home Builders Institute educational arm, as well as the United Brotherhood of Carpenters union, to "transition them from stick-framing to ICFs and concrete," Niehoff says. Owens Corning, meanwhile, announced a training and certification program for its ICF system earlier this year.
As for distribution, the ICF industry seems typically fragmented for a relatively young industry. While some manufacturers are actively initiating direct sales relationships with builders to help keep prices competitive, others are willing to suffer supply channel markups of up to three times the cost of a block to enable local support for the technology. "A manufacturer 1,000 miles away can't provide the level of support that a local dealer can," says Dave Zimmerman of WinForm, an ICF distributor in Brodhead, Wis.
Even so, the regional, two-step distribution model will likely continue to dominate. "Some dealers are getting into it, but the distribution right now works well [for the industry]," says Niehoff. "Distributors are knowledgeable about the product, have a secure geographic territory, and want to focus on selling ICFs and training others [contractors] to install them."