Can I Cover Blown Fiberglass Insulation in the Attic With Paper?

Paper

• You can apply paper to insulation as a vapor barrier. The most common type of paper used in conjunction with insulation is Kraft paper with an asphalt coating. This provides a barrier to vapor, preventing condensation from forming on the insulation. It can also act as a deterrent to insects, preventing them burrowing into the insulation and compromising its insulating power. Such paper is common as facing on fiberglass batts. The batts are installed with the paper facing the interior of the room.

Paper on Blown-In Fiberglass

• Because blown-in fiberglass insulation does not attain a uniformly flat surface, unlike batts, the application of a paper covering is unlikely to provide effective protection. Paper affixed to an uneven surface will contain air voids that will allow air and moisture to penetrate the fiberglass and reduce its effectiveness as an insulator. If you do choose to use paper, install it on the room-side of the insulation, as opposed to blowing the insulation onto it, and try to get it as flush as possible with the fiberglass.

Caution

• If you choose to cover your fiberglass insulation with paper, be advised that the paper is flammable. Fiberglass insulation is naturally fire-resistant, but the paper coating may ignite if subjected to high enough temperatures. On its own, fiberglass insulation will melt but not catch fire.

Alternatives

• There are a number of alternatives to cover blown-in fiberglass insulation to provide a moisture barrier. Polythene plastic and aluminium foil are prey to the same problem as paper of covering an uneven surface with a flexible membrane. As such, it's more effective to install a rigid form of covering, such as plywood.