Blown-in insulation is a loose fibrous form of insulation that we blow into cavities and other hard-to-reach areas. There are two main types of blown-in insulation: The first is fiberglass, which is most commonly used for attic insulation. The second is cellulose, which is basically shredded paper and is most commonly used in wall cavities and the spaces between floors and ceilings. It is an effective form of insulation to use for post-construction installation because it does not require open access to the floor and wall cavities. We can blow the insulation through small drill holes that we can plug up when the work is done.