Blown Insulation for Attics: Fiberglass vs. Cellulose
Both perform better than batts and are less expensive than spray polyurethane. Neither is perfect.
Fiberglass-batt insulationInsulation, usually of fiberglass or mineral wool and often faced with paper, typically installed between studs in walls and between joists in ceiling cavities. Correct installation is crucial to performance. is inexpensive but difficult to install well. Framing members aren’t always spaced perfectly, and it’s awkward to fit batts into irregularly shaped cavities and around electrical wires and boxes. Because few insulation installers have the patience required to install batts carefully, insulation performance suffers.
[To read more of Martin Holladay's article from the December 2010/January 2011 issue of Fine Hombuilding, click the link below.]