Flashing refers to thin pieces of continuous material used to weatherproof a home and prevent the entrance of water. Roof flashing is placed on the roof and over any area where two sides or joints come together, like around a chimney or pipe. Base flashing refers to the material used around the house, while wall flashing may be embedded into walls to direct water that has gotten inside back out. Sill flashing can be found under window sills or door thresholds, halting water’s entrance at those points. While essential to ensuring a home’s continued integrity, one of the materials historically used to construct it makes it a health threat.
Though now constructed of safe metals, past flashing was often constructed of the durable material, asbestos. The adhesive used to attach the flashing was also often made with asbestos. In fact, many adhesives on the market today still contain trace amounts of asbestos. Even if the flashing is made of asbestos-free metals, the thin layer of material placed between the flashing and the wood structure of a home was typically made with a material that contained asbestos as well. This felt liner can be easily torn when flashing is repaired or removed. When torn, the asbestos fibers are released into the atmosphere, causing serious illness and disease in those exposed.
Like many other roofing materials banned by the EPA, owners of older homes are cautioned against removing these materials themselves before consulting a professional with experience dealing with asbestos-containing materials. Its ability to withstand high degrees of heat, humidity and strain made asbestos a popular material for use in home construction areas, especially roofs, which take the brunt of exposure to the elements. In some cases, roof flashing contained chrysotile asbestos quantities of ten percent or greater. Reference: EPA