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Sponge Block

Asbestos in Sponge Block and Other Building Materials

Sponge block is a type of insulation material, generally used in applications requiring heat resistant capability. While sponge block can be found under roofs and inside walls, it is more often used around water heaters, steam pipes and other conduits where heat may pose a fire danger. Sponge block was often used for roofing in warehouses, garages, outbuildings, and other utility buildings.

Sponge block was made from a wide variety of materials, including polyurethane, Styrofoam, plastic, and other lightweight, porous materials. The common element was that sponge block contained up to 20% asbestos fibers by weight. This made it highly resistant to fire, heat, and corrosion.

While the use of asbestos in building materials was phased out in the early 1980s, the regulations then in force covered only the manufacture of new materials, not those which may have already been on retail shelves. Therefore, it is possible that some asbestos sponge block was installed in homes throughout that decade as well as in the previous years.

Hazards Associated with Sponge Block Products

Asbestos sponge block insulation posed serious health threats in two primary instances: 1) upon installation if it had to be cut to size and 2) when it started to started to age and deteriorate decades after the original installation. In both situations, the potential for asbestos fibers to enter the air where they could be inhaled by those working in the vicinity existed.

The health hazards of inhaled asbestos include the build-up of scar tissue on the inner surfaces of the lungs, a condition known as asbestosis and thickening and stiffening of lung tissue, or pleural thickening/plaques. Certain types of asbestos, such as blue crocidolite or brown amosite mcan also result in cancer of the visceral lining of the lungs, pericardium or abdomen, a cancer known as mesothelioma.

Should you find asbestos sponge block in your home or have reason to suspect that it exists, do not attempt to remove it yourself; call a licensed asbestos abatement service (if you are a landlord or building owner, you are required to do this by law in most states).



Bowker, Michael. Fatal Deception: The Untold Story of Asbestos (New York: Touchstone, 2003)

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