In almost every industry one product dominates its category like no other and is the leader that others chase. One example of this is fiberglass batt insulation.

Fiberglass is an excellent sound absorber and energy saver, says the Alexandria, Va.–based North American Insulation Manufacturers Association. And the inexpensive product is one of the most cost-effective ways to save energy and reduce heating and cooling bills. No wonder the market share of fiberglass hovers around 85 percent.

But an increasing number of builders and architects consider sprayed foam insulation to be a superior product. It is the fastest-growing segment of the insulation market, and many industry observers believe that it will soon displace fiberglass as the product of choice for builders and home buyers.

Filling The Lanes Typically sprayed into stud cavities, foam insulation expands to fill all nooks and crannies. It is easier to install, safer for the environment, and more energy-efficient than traditional batt insulation, according to “Insulation Alternatives: Sprayed Foam Insulation,” a report by ToolBase Services, a technical resource division of the NAHB Research Center in Upper Marlboro, Md.

“It creates a tighter house,” says Cindy Burke, director of marketing for Tukwila, Wash.–based Gaco Western, a manufacturer of foam insulation. “It fills tight cracks, you can spray around wires, and it does not sag.”

Foam insulation comes in two types: soft and rigid. Blair Johnson, national sales manager for Bozeman, Mont.–based Corbond, a maker of rigid foam insulation, says the rigid product is better. “The perm rating is low,” he says, “so it allows less humidity to come into the home. It is also a built-in vapor barrier.” The R-value rating for soft foam is about 3.7 per inch, while rigid foam has an initial R-value rating of 7 per inch. And because rigid foam cures stiff, it helps construct a stronger wall.

“Foam is the Cadillac of insulation,” says Steve Mugg, a division manager at insulation installer Moore Insulation in Cheyenne, Wyo. “With oil prices and energy issues being the way they are, it is the best way to go. It also adds structural strength to houses on the high plains of Cheyenne.” Moore, which is currently installing its product in a subdivision of 500 homes, started offering foam five years ago, and sales for the product have grown from $250,000 to $1.5 million. “In our market, it makes perfect sense,” Mugg says.

Cost Concerns Despite all the benefits, sprayed foam costs considerably more than fiberglass. The extra cost varies but can run anywhere from 10 percent to 15 percent more per house or per job, Burke says. Manufacturers note, however, that the added cost is offset by a corresponding reduction in construction costs: Builders save by downsizing their HVAC systems, and Johnson says that in northern climates, where walls need to have an R-19 rating, builders can achieve that mark and save money by using 2x4s. Builders using fiberglass must use 2x6s, which cost more.

There also is some debate as to whether rigid foam insulation costs more than the soft version. Rigid foam definitely is a high-performing product, but “it is not an economical system,” says Don Tiskevics, vice president of sales for BioBased Systems, Spring Valley, Ill., manufacturer of a soybean-based foam insulation called BioBase 501. Tiskevics says, for example, that a kit of the company's soft foam product will yield 15,000 to 16,000 board feet of coverage vs. 3,500 to 4,500 board feet for a rigid kit, depending on the manufacturer.

Cost will be a pivotal issue if foam is to grow with production builders. Though Moore Insulation is having success with large-volume builders, foam insulation in general has not had much success with this segment. The industry says that is starting to change. “We are in our infancy [with that market],” Corbond's Johnson notes. “I think we are just starting to move into that market.”

Climate Isolation: The Corbond rigid foam system completely isolates interiors from outdoor weather conditions, the company says. It works preventing interior heating and cooling from mixing with the exterior climate, whether hot or cold. As seasons change, the system is unaffected by the reversal of moisture drives. The company says the indoor and outdoor climates are effectively displaced from the cavity permanently as the product is installed. Corbond Corp. 888-949-9089.

Energy Saver: Icynene soft foam insulation is 100 percent water-blown, contains no harmful emissions, and permanently adheres to construction materials without shrinking, sagging, or settling. It allows builders to downsize the HVAC system, so home buyers can save on equipment costs and energy bills, the manufacturer says. Icynene. 800-946-7325.

Star Gazing: Because InsulStar foam insulation is formulated from renewable agricultural resources, it is one of the most environmentally friendly, closed-cell products on the market, the company says. It prevents thermal and moisture transmission, making a separate vapor barrier unnecessary. Plus it has a special mold and mildew inhibitor for extra protection, and will not settle, shrink, or deteriorate. NCFI. 866-678-5283.

Joy Of Soy: BioBase 501 is the most environmentally friendly insulation in the industry, the manufacturer claims. The ultra-lightweight product is a two-part, soybean-oil–based system. The company says the product eliminates building wrap, caulking, taping, and other labor-intensive work associated with attempts to create a tight building envelope. BioBased Systems. 800-803-5189.

Easy Green: The manufacturer says GacoGreen spray-in foam insulation contains no unsafe chemicals, ozone-depleting compounds, or formaldehyde. It can be applied to wall cavities, ceilings, and subfloors to prevent air infiltration and sound absorption. The product has a 4.2 R-value per inch. Gaco Systems. 800-331-0196.