R-38 cellulose is 10.seventy seven inches thick; R-38 fiberglass is 12 inches thick. Fiberglass weighs a lot less than cellulose, which is not a Think about an attic but may be a Think about a garage, such as. Cellulose and fiberglass have numerous related characteristics, but at the end of the working day, it comes all the way down to a homeowner�