All About Insulation

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CONVENTIONAL INSULATION OPTIONS

Fiberglass, cellulose and rigid foam board are most commonly used as home insulation because they are economical, readily available and familiar to most contractors.

Fiberglass is made from one of the world's most abundant materials, silica sand, which is heated to high temperatures to produce glass and then spun into microthin fibers. The most popular insulation product on the market today, fiberglass comes in two forms: blankets (batts and rolls) and loosefill. Paper-backed blankets are installed in wall cavities and between floor joists. Unbacked blankets and loosefill fiberglass are installed in ceilings. Loosefill fiberglass insulation also can be blown into wall cavities.

Although these products are fairly inexpensive and effective, they pose some health risks: Cancer warnings are posted on most fiberglass insulation sold in the United States.

One of the chief problems with this insulation is that microscopic slivers of glass may break loose during handling and installers may inhale it. Fibers can irritate the lining of the respiratory tract and may become lodged in lung tissue, causing a buildup of fibrous tissue that reduces lung capacity.

Laboratory studies show that the fibers may shear DNA molecules in the nuclei of cells, causing mutations that could lead to lung cancer. Although inhalation of fibers during installation can be prevented by wearing a respirator or a certified dust mask, all three principal U.S. manufacturers of fiberglass insulation have addressed the problem by sealing fiberglass batts in a perforated polyethylene or polypropylene sheeting, which also acts as a vapor barrier.

Standard fiberglass insulation has typically been made with a formaldehyde-based binding agent, which holds the fibers together. But this binder outgases (gives off chemical vapors) and can affect both installers and home occupants. Besides being a skin, eye and respiratory irritant, formaldehyde is classified as a probable human carcinogen by the U.S. Environmental Protection Agency.

Some manufacturers, such as Owens Corning and Johns Manville, have introduced formaldehyde-free fiberglass insulation products. Miraflex, an Owens Corning product, contains two types of glass fiber that expand and contract at different temperatures. This causes the fibers to curl and twist, which helps them bind together without chemicals. Miraflex is soft and nonirritating to skin. Moreover, the fibers have greater tensile strength than those in standard fiberglass insulation. Johns :Manville has replaced the formaldehyde binding agent in all of its products with a nontoxic acrylic resin.

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