Randy writes from Effingham, Illinois: “WHAT IS THE STC COMPARISON BETWEEN MINERAL FIBER INSULATION AND FIBER GLASS?
According to testing at the National Research Council Canada (NRC-CNRC) performance of the two products is essentially the same. Depending on the assembly, testing of equal thicknesses of mineral wool and fiber glass typically result in STC results within one to two points of each other. When one tests better than the other it is almost always the fiber glass. Remember that STC ratings are just a quick reference and an assembly that tests better for STC may not always be the best choice for a specific application.
