Eco-Experts: Learn About Insulation Options, Rust-Proofing and Composting Dog Waste

Get the eco-friendly answers to your questions.

| July/August 2003

  • Beth Scott
  • Carol Steinfeld
  • Joe Hurst-Wajszczuk

Insulation options

My husband and I are interested in further insulating our attic and insulating our floor/crawl space. We want something breathable and nontoxic. We are concerned about the standard fiberglass.

—Sarah Carson, via e-mail

Believe it or not, fiberglass insulation is relatively natural. It's made from silica sand and as much as 30 percent recycled glass. What's more, it's inexpensive, resistant to mold, and indigestible to insects. However, the microscopic slivers of glass irritate uncovered skin, and greater exposure to the particles can lead to permanent respiratory ailments. Some researchers suggest it can induce cancer. In addition, some batts contain formaldehyde-based binders that may outgas after installation.

To address the particle problem, all the major manufacturers now offer sealed batts. The perforated polyethylene sheeting controls loose particles and doubles as a vapor barrier. To solve the formaldehyde problem, Johns Mansville now uses a nontoxic acrylic binder. Owens Corning has developed a product that binds fibers together without chemicals.

If you're still concerned about fiberglass, there are other options. Mineral wool insulation is similar to fiberglass, but the fibers are derived from iron-ore blast furnace waste. Although heavier and more expensive than fiberglass, mineral wool is more moisture-resistant and maintains its insulative properties when wet. During handling, however, small pieces can break loose, which raises health concerns similar to fiberglass.

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