Fiberglass Batt Insulation is a light-density fiberglass blanket used in residential and commercial construction for thermal and acoustical insulation of walls, ceilings and floors. Fiberglass Batts: Are non-combustible Are non-corrosive and do not rot, mildew or deteriorate Do not absorb moisture Are lightweight and flexible, and can be easily cut for irregular areas. Fiberglass Batts have been the standard of the insulation business for the past 50 years. Apex reputation was built on the qulity installation of fiberglass batt insulation. When combined with an air sealing package, such as foaming around doors, windows and penetrations with low expansion foam, it can still help to mitigate some of the energy loss of a home or structure..