Fiber glass batt insulation is a type of insulating material used in most home attics. It is a flexible sheet of insulation that comes precut to fit in between the rafters of home attics we use is certified to contain 58% recycled content and is GREENGUARD certified to be formaldehyde free. It is very efficient and less dusty when installing compared to blow in insulation, but its main drawback is the difficulty of installation. The material cannot be compressed and has to be installed without any gaps.