Cellulose attic insulation is an alternative material to fiberglass and has some advantages compared with the latter. It is useful for insulating oddly-shaped cavities behind walls and ceilings and areas blocked by plumbing, air ducts, or wiring—places fiberglass won't fit.
Cellulose attic insulation is made from 100-percent recycled products, such as plant-resin scraps or shredded paper. Compared with fiberglass insulation, it consumes less energy to create and is more environmentally friendly.
It is mixed with low-toxicity chemicals, such as fire retardants, to give it greater durability and make it a stronger insulator. The borates used as fire retardant in cellulose insulation also keep pests out and deter mold production.
Cellulose material has a lot of advantages over fiberglass, such as its thermal performance. As mentioned above, it fits well in small crevices and cavities. This reduces the avenues for outside air (or treated air from inside the house) to breach the attic walls.
Besides that, cellulose is both an efficient sound barrier and a vapor barrier. It is the only kind of insulation that does not require an additional vapor barrier.
Since loose cellulose attic insulation is easy to apply, homeowners tend to go overboard, ending up with a lot of excess insulation and no idea what to do with it. The best way to remedy this is with a wet-dry vacuum, which allows you to remove cellulose material whether it is moldy, dry, or wet. As you vacuum up the excess, empty out the machine regularly so it doesn't get clogged and stop working.
Do not throw out the cellulose insulation when you are done; it is made of recycled material, such as paper, and can be dealt with properly at a recycling center.