What is CertainTeed insulation made of?

CertainTeed residential insulation is primarily made of fiberglass, which is composed of molten glass spun into fine fibers. The raw materials are silica sand, which is the main ingredient of glass, plus recycled glass content, typically 30 to 40 percent recycled bottle glass and plate glass, melted in a furnace at over 2,500 degrees Fahrenheit. The molten glass is then spun through fine holes to create thin fibers that trap air pockets, providing thermal resistance. Historically, fiberglass insulation used a phenol-formaldehyde binder to hold the fibers together, but modern CertainTeed Sustainable Insulation uses a plant-based, formaldehyde-free binder made from renewable bio-based materials that is less irritating and has low volatile organic compound emissions. This binder is what gives newer CertainTeed batts a lighter, softer feel and a slight natural color rather than bright yellow. CertainTeed also adds a small amount of mineral oil for dust suppression. For its blown-in insulation, CertainTeed InsulSafe SP is made from similar unbonded fiberglass fibers without a binder, designed to be fluffy and blown with a machine. CertainTeed also manufactures other insulation types. Its rigid foam products are made from expanded polystyrene or polyisocyanurate foam, and its MemBrain smart vapor retarder is made from a polyamide film that changes permeability with humidity. All fiberglass products are GREENGUARD Gold certified and asbestos-free.