Transite is a composite material used in construction for fireproofing. Though it was originally sold by the Johns-Manville Corporation as a trade name, the term “transite” came to apply to other brands of similar products. From 1920 until 1980 transite was made with Portland cement and was 12 to 50 percent asbestos. Roofing shingles were made from transite as were shingles and boards for siding, cement siding, and furnace flues. It was also used to tile floors and insulate coolers. It was very popular for the forty years between the mid 1930s and the mid 1970s before the public became aware of the dangers of asbestos.
Transite roof shingles were usually made with chrysolite asbestos and cement. This resulted in a very rigid material resembling boards that could be molded and cut into various sizes to use as siding, floors, or roof tiles. As long as the transite isn’t damaged by erosion, weather, or drilling there is no serious risk of asbestos exposure. But once it deteriorates so much that it can be crumbled with the hands, it is hazardous because the fibers can become airborne. The people who worked in the factories that made transite were likely exposed to the asbestos, which can cause asbestosis, lung cancer, and mesothelioma.