R-38 cellulose is 10.77 inches thick; R-38 fiberglass is 12 inches thick. Fiberglass weighs lower than cellulose, which is not a factor in an attic but may be a Think about a garage, by way of example. Cellulose and fiberglass have a lot of equivalent qualities, but at the conclusion of the day, it comes down to a homeowner’s choice. When you’r