At the beginning of the 20th century, asbestos cement shingles were introduced, offering the consumer a new way to roof buildings. The material was less expensive than traditional roofing material and provided additional fire protection and durability. For over five decades the product was popular, yet it was eventually discovered that exposure to asbestos could be a serious health risk.
In 1900, Austrian Ludwig Hatschek invented a process to manufacture rolled and pressed asbestos cement sheets. His 1907 United States patent spurred rapid production of the asbestos cement roof shingles. Hatschek called the process eternit, which became the name of one American manufacturer that produced the asbestos cement roof shingles. By the 1970s, concerns were being raised about the health hazards associated with manufacturing and working closely with asbestos products. Today, Eternit makes asbestos-free shingles.
Asbestos cement roof shingles were made from asbestos--an inorganic, fibrous material--and cement. The shingles were marketed to replace familiar roofing material of the era, which included slate, wood and clay. Pigments were added to the wet mixture, allowing the shingles to be available in various colours. Unfortunately, early asbestos cement shingles faded with time. The shingles came in an assortment of textures, such as weathered wood or a rough rustic texture. This feature was made possible by the hydraulic pressing process during production.
The shingles usually contained less than 30 per cent asbestos fibres, and were later classified as being an "asbestos containing material," or ACM. The fibres were mixed with cement and moulded, then cut into the desired shape. Holes were often drilled to help align the shingles when roofing a building. The shingles were not just used on new roofs; they sometimes were applied over an existing roof.
Asbestos cement roof shingles were lightweight, resisted fire and were inexpensive. They provided the consumer with a new and affordable building material option. In 1910, one asbestos shingle company advertised its product as being superior to any natural slating material. The material promised additional home safety. Also, due to its fire-resistant quality, it gave the consumer additional choices in colour and texture while saving money. The roofs were also durable, some companies claiming they could last up to 100 years.
In the 1970s, the public became aware of the dangers of asbestos. While roofs with asbestos cement shingles are not believed to pose a public health danger, working with or producing products that contain asbestos can pose serious health risks. When the shingles begin to deteriorate, or if the building with the shingles is being demolished, there is danger associated with the breakage of the shingles. Mesothelioma, a form of cancer, is one of the health risks associated with exposure to asbestos. Building materials that contained asbestos were still being made in the United States in the 1980s. Yet, changes were made, halting the production of asbestos products.
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