Fiberglass is one of the most commonly used insulation materials. It consists of extremely fine glass fibers and is used in two different insulation forms: blanket (batts and rolls) and loose fill.

1. Fiberglass Blanket (Batts and Rolls) Insulation Manufacturers now produce medium- and high-density fiberglass batt insulation products that have slightly higher R-Values than previous varieties. The denser products are intended for insulating areas with limited cavity space, such as cathedral ceilings.
2. Fiberglass Loose-Fill Insulation                                   Fiberglass loose-fill insulation is made from molten glass that is spun or blown into fibers. Most manufacturers use 20%–30% recycled glass content. Loose-fill insulation must be applied using an insulation blowing machine; it is designed for open-blow applications (such as attic spaces) or closed-cavity applications (such as those found inside walls or covered attic floors).