Made from rock, blast furnace slag, and other raw materials which are melted and spun into fibers to resemble the texture of wool. Mineral wool comes in batts, rolls or loose-fill forms. Rock-wool insulation can be installed wherever you’d install fiberglass or any other type of insulation, including walls, floors, ceilings, attics and crawlspaces. However, it’s particularly well-suited for rooms along the cold north side of the house and for interior rooms in need of sound deadening. Because rock wool is highly fire resistant, it’s ideal—and often code-required—for use as a firestop between floors of a house.