Tommy Mac Discussions › Forums › Fix-it Forum: Home Improvement & Do It Yourself Repair Forum › Cellulose on top of fiberglass insulation › Good Question……
October 16, 2002 at 12:40 pm #121588
Cellulose that is blown in properly will be light enough to have minimal effect on the fiberglass. However, there will be some settling. Say you have R15 worth of fiberglass in the attic now, and you blow in R15 worth of cellulose on top of it. I would estimate that your total R value will probably be in the order of R27 instead of the theoretical R30. Still well worth the effort.