Fiberglass is a synthetic or man-made material that consists of tiny fibers of glass. It is a common source of insulation in homes. Fiberglass can enter the environment when it is manufactured, ...

R-value is found by multiplying thickness in inches by a number from 2.5 to 3.7 (based on insulation type). Fiberglass fiber has the lowest R-value, and cellulose (newsprint) the highest. If your ...