Fiberglass insulation comprises of extremely fine glass fibers. It is an insulation that is found mostly in your homes. It is commonly used in two different types of insulation – blanket which is batts and rolls, and loose fill. It is also available as rigid boards and duct insulation.Fiberglass as an insulator slows the spread of heat, cold, and sound in structures. The material does this by trapping pockets of air, keeping rooms warm in the winter and cooler in the summer. Fiberglass insulation is made of plastic reinforced by tiny glass fibers. This composition gives the plastic additional strength while improving its insulation capacity.