Duplex Blox

It may sound like a popular child’s toy, but actually, duplex blox is an insulating material found in many boiler pipes and hot water tanks, and in many insulated walls and ceilings. Usually offered as a preformed block, the material is naturally chalky, becoming more powdery with age, and was often held in place by wire or wood lath installations. Duplex blox was considered an effective and useful insulation, and was installed in many residential and commercial buildings, and used in a wide range of industrial applications.

Duplex blox and asbestos

Like about 3,000 other construction materials manufactured in the United States prior to 1977, duplex blox contained a large percentage of asbestos. Prized for its strength and resistance to heat and corrosion, on the surface the fibrous asbestos material seemed an ideal component for many construction materials, including duplex blox. Readily available and relatively inexpensive, the benefits of asbestos seemed evident to both the manufacturer and the end-user. But time would prove differently.

Even at the point of manufacture, duplex blox is not regarded as a structurally stable material, and over time, the product degrades easily and wears away. As buildings and homes are upgraded or renovated, often to meet new environmental guidelines or to offer a relief from high heating bills, this material easily chips and flakes away, resulting in the tiny particles of fibrous asbestos being released into the air. Once inhaled, these fibers can scar the lungs, causing mesothelioma and other cancers. In the United States, legislation in 1977 prohibited the use of asbestos in the manufacture of building and construction materials. However, existing stocks were allowed to be used until depleted. As a result, the majority of buildings constructed prior to the mid-1980s contain asbestos-based construction materials, including duplex blox. And there’s a very good chance that anyone working in the construction or HVAC industries prior to that time was exposed to these materials, either during their use or manufacture. But the risk doesn’t end there. Today, as many homes and buildings “go green” by upgrading and updating heating systems and insulation, those who perform the renovations, and work or live in the buildings being renovated, are at risk for exposure to potentially deadly asbestos fibers.

Last modified: December 09 2009.