CertainTeed® CedarBoards™ double 6-inch clapboard insulated vinyl siding now contains 60 percent recycled material. CertainTeed has developed a network of recyclers and a workable formula that meets the company’s stringent quality guidelines. Recycled materials, including scraps from job sites, vinyl siding distributors and other post consumer sources, are integrated into the manufacturing process and verified by a third party auditor on a quarterly basis.