Safety of Rock and Slag Wool Insulation

Rock and slag wool fall within a group of materials historically referred to as man-made vitreous fibers, now known as synthetic vitreous fibers (SVFs) - reflecting the glassy, non-crystalline nature of these materials. The mineral wool form of SVF was developed in the mid-1800s by melting slag and spinning it into insulation. Rock wool is made from natural minerals like basalt or diabase. Slag wool is made primarily from iron ore blast furnace slag.

Rock and slag wool insulation products play a significant energy-savings role by reducing energy use in homes, office buildings, businesses and manufacturing plants. In addition to providing thermal insulation, rock and slag wools absorb sound and, with a vapor retarder, help control condensation. Because they are non-combustible and have melting temperatures in excess of 2,000 degrees Fahrenheit, they are also used to prevent the spread of fire. Rock and slag wools will not support the growth of mildew, mold or bacteria, when tested in accordance with the specifications of the American Society for Testing and Materials (ASTM C 665).

The primary uses of rock and slag wool are for acoustical ceiling tile; residential, commercial and industrial insulation; and spray-on fireproofing. The excellent thermal resistance of these materials is a major factor in their use as residential and commercial insulation, pipe and process insulation, insulation for ships, mobile homes, and domestic cooking appliances, and a wide variety of other