Expansion of Spray Polyurethane Foam

According to a 2008 study conducted by The Freedonia Group, the U.S. construction-insulation-materials market is expected to exceed $11 billion in 2012. Fiberglass controls approximately 85 percent of the U.S. home insulation market, cellulose is 10 percent, and spray polyurethane foam, or SPF, is a little less than 5 percent — $200 million.

According to the Fairfax, Va.-based Spray Polyurethane Foam Alliance, SPF has one of the highest insulating R-values — up to 6.0 per 1-in. thickness — of the available insulation products on the market. SPF insulation also provides an air barrier, which protects homes from moisture, pollutants and pests. These factors combined with sustainability aspects and safety features deliver an impressive future for the SPF insulation industry.

What Is It?

SPF insulation is a two-component system, consisting of an A side and a B side. The A side is a petroleum-based polymeric isocyanate. The B side is a blend of polyols (the building blocks of foam), blowing agents, flame retardants, surfactants and catalysts. The two sides together create the foam. In a residential application, the product can be used in walls, floors, unvented and vented attics, basements and ceilings.

“Portable and disposable SPF systems require no outside source of power to use them,” explains Mark Wojtiuk, general manager, RHH Foam Systems Inc., New Berlin, Wis. “They are designed such that the chemical reaction between the two components causes them to expand and create the final SPF product.”

“Spray foam is sprayed in as a liquid that quickly expands multiple times in size to fill cracks and gaps,” says Jennifer Wilson, brand manager for BioBased Technologies, Fayetteville, Ark. “This seals the structure, and a sealed thermal envelope allows building occupants to efficiently and effectively condition the air inside a home.”

Low density, open-cell SPF weighs between 0.4 to 0.6 lbs per cu. ft., typically uses water as a blowing agent and has an R-value around 3.5 per in. Medium density, closed-cell SPF usually weighs between 1.5 to 2 lbs. per cu. ft., uses a high R-value blowing agent and has an R-value of around 6.0 per in. High-density SPF weighs 2 lbs. per cu. ft. with R-values ranging from 5.5 to 6.5 per in. and also uses a high R-value blowing agent.

Despite SPF’s benefits, some homeowners run into sticker shock when they initially compare SPF to more traditional insulation systems, which can cost three to four times less.

In addition, spray foam’s seamless barrier inhibits growth of mold and bacteria. “Closed-cell spray foam controls moisture well enough to satisfy current International Code Council [Washington, D.C.] requirements without an added interior vapor retarder in most applications,” says Tom Sojak, vice president of sales, Gaco Western’s WallFoam division, Seattle. “It also offers significant structural value.”

Due to its inherent strength, closed-cell SPF will structurally reinforce the insulated area. It contains tiny cells that are packed tightly together and are filled with a gas that makes the foam expand. In open-cell SPF, the cells are not completely closed and expansion occurs as air fills the open space. The advantages of closed-cell foam include its strength, higher R-value, and strong resistance to air and water vapor. On the other hand, open-cell foam is not as dense so it requires less material and therefore is less expensive.

All SPFs significantly reduce sound transmission by sealing cracks and gaps, thereby preventing sound to travel through the walls, floors and ceilings. Since high-density, closed-cell SPF rigidly adheres to both the exterior sheathing and the studs, it can also deaden the sound caused by vibrations and strong winds.

Homeowner Interest

SPF addresses consumers’ top-of-mind issues, including home comfort and energy efficiency. The effective air seal created by SPF reduces energy loss and moisture penetration, as well as limits entrance of outdoor allergens and pollutants that can affect the comfort of a home.