Structural insulated panels serve as both roof (left) and wall panels (right) for the home's structural frame. Like ICFs, the system speeds cycle time and improves energy efficiency; as a wood-based system, however, SIPs might be easier for builders and framers to employ.
Credit: Courtesy Sipa
Like ICFs, structural insulated panels combine multiple building materials into one, sandwiching a thick foam panel between two layers of OSB to create structural wall and roof sections. The resulting panel is ready to finish on both faces, reducing cycle time. It also creates a thermally superior and more reliable envelope to a stick-framed house; a 4-inch SIP wall is 36% more thermally efficient than an insulated 2x4 wall, according to the Oak Ridge National Laboratory (part of the Department of Energy) in Oak Ridge, Tenn.
According to NAHB research, SIPs were used as the structural wall material for 1.7% of all new, single-family homes built in 2005, a full percentage point higher than five years earlier and now representing nearly 30,000 new homes annually.
Despite its small share, the technology's upside is perhaps even greater than ICFs'. Simply, SIPs are a wood-based system, making them more familiar to framers than a concrete alternative. As such, SIPs are easily manipulated on site with common construction tools, are compatible with other wood framing materials and practices, and offer greater design flexibility and mainstream marketability. As full wall panels, they often assemble even faster than ICFs, and require no pour or cure time. Those savings help balance a 15% or more materials-only price difference between SIPs and stick framing, one of several hurdles the industry faces in its fight for market share.
SIPs' installed cost savings, and the system's energy-saving benefits, are what drove Ferrier to the technology. "When buyers are looking for a truly high-performance home, you can't build the standard way," he says. "SIPs give me the biggest bang for my energy-efficient buck."
The market share for SIPs, forged in the custom-home realm, could get a big boost if other large-volume builders follow the lead of Pulte Homes, the nation's second-largest builder. Two years ago, the company opened a manufacturing plant in Manassas, Va., under its Pulte Home Sciences Division, to build a variety of engineered building systems, including SIPs. The panels, reports the builder, shave nearly three weeks off of its already efficient production schedule, and with less skilled labor. Pulte has used the technology to build 1,000 new homes near the facility and plans to expand its geographic reach as the operation ramps up to full capacity.
Historically hindered by building code acceptance, especially at the local level where building inspectors are typically wary of new methods and materials, recent advances on that front should help. A recently released prescriptive method for SIP wall construction developed by the Partnership for Advancing Technology in Housing, should grease SIPs' road into housing's mainstream. The standardized method for calculating and using SIPs enables builders to gain code approval without the stamp of a licensed architect or engineer and puts the technology on par, code-wise, with ICFs and steel framing in residential construction.
The question is whether the SIPs industry is ready for a larger wave of demand from the housing industry. "We're seeing more demand, but there aren't experienced and qualified contractors in the field to install it," says Al Cobb, director of SIP School, an outreach education and training effort based in Shenandoah Junction, W.Va.
Like ICFs, the SIPs industry also is still grappling with its supply chain model. Bill Wachtler, executive director of the Structural Insulated Panel Association in Gig Harbor, Wash., isn't aware of any lumberyards currently stocking SIPs, though some may be acting as distributors or middlemen. "It's been talked about on a number of occasions, but you simply can't throw an 8-by-24 [SIPs] panel in the back of a pickup," he says. "I could see a customer ordering SIPs as an option when purchasing a house package [from a dealer], but not walking down an aisle and picking out a panel."
Manufacturers and even SIPs builders also seem hesitant to turn the reins over to local dealers. "At a lumberyard, you can just swing by and grab a few sticks from the pile when you need them," says Gary Pugh, a SIPs builder and industry advocate in Santa Rosa, Calif. "With SIPs, you have to think about them long before you start building."
Though Wachtler can envision LBM dealers one day supplying SIPs, the most likely scenario is one in which manufacturers sell their systems through existing component manufacturers. "As that industry matures in supplying wall panels, it becomes a faster distribution route for us," he says. "They already have the engineering, equipment, and expertise in making and selling wall systems to builders and lumberyards."
Until then, builders are left to look for the best SIPs they can find and afford, often going out of market to get them. Ferrier, for instance, has his panels shipped from 800 miles away. Both he and Pugh, however, still rely on their local LBM dealers for interior studs, windows, millwork, sealants, and fasteners. "They give us referrals [to consumers asking about SIPs]," says Pugh. "It's not a threat."
At least in the short term, says Pugh, lumber dealers interested in selling SIPs will likely be kept on a tight leash. "If lumberyards are willing to work with suppliers as a sales conduit and logistics partner, it could be a good marriage," he says.
–Rich Binsacca is a contributing editor for ProSales.
EDITOR'S NOTE: See how steel framing and precast concrete are faring in home building and LBM supply in part two of this series in the May issue.