CertainTeed Corp. (Valley Forge) CertainTeed Corporation is one of the largest manufacturers of building materials in the world and serves both the commercial and residential construction industries. Headquartered in Valley Forge, Pennsylvania, the company is a wholly-owned subsidiary of Compagnie de Saint-Gobain in France. From its very beginnings in 1904, CertainTeed has been a leader in the design and crafting of innovative products in every aspect of construction materials. George M. Brown founded the General Roofing Manufacturing Company in the St. Louis area and his firm quickly became one of the largest roofing material manufacturers in the region. Within a few years, the company was producing a variety of shingle types as well as wood and metal roof coverings. Brown incorporated the company in 1917 and soon the operations expanded to include gypsum particle board and plaster manufacturing. In the 1930’s, the Celotex Company purchased the majority of CertainTeed's stock and the company, which had been headquartered in New York, relocated to Chicago. In later years the company would relocate once more to Pennsylvania and begin production of specialty cement products, fireproof gypsum boards, and vinyl siding and windows. Today CertainTeed is renowned for its innovative product developments, including spray polyurethane foams, building trims, PVC pipes and other plastics. The company exports its materials to over 50 countries around the globe, and has been awarded numerous government and defense contracts. CertainTeed employs approximately 10,000 workers in its various locations and has revenues in excess of $3 billion. Between the 1930s and the 1980s, CertainTeed developed a number of products that contained asbestos and other toxic materials. This was primarily due to the fact that asbestos is an ideal insulator and fire-proofing substance. Asbestos has often been used to wrap pipes, make ceiling and walls flame-retardant, and as a material in protective clothing, especially for workers who perform operations in areas of high heat. When government warnings about the dangers of asbestos exposure were backed up by medical professionals, companies such as CertainTeed began eliminating this dangerous material from its production lines. Asbestos fibers are light, can break off into small pieces and remain airborne for a long period of time. They can be inhaled by individuals and the fibers collect in the lungs. Asbestos is a known cause of mesothelioma, a cancerous affliction that often shows no symptoms until many years after repeated exposure. CertainTeed Corporation no longer uses asbestos in any of its building materials, cements, plasters, or insulations. The number of CertainTeed employees that were exposed to asbestos in the past is unknown.