Is Paper Backed Insulation Used as a Vapor Barrier?

Faced Insulation

• Insulation provides resistance to heat flow, but does nothing to prevent airflow. Because of this, fiberglass insulation manufacturers provide paper- or foil-faced insulation batts that will double as a vapor barrier. While these barriers diffuse or retard water vapor, they don't stop it completely. The same is true of vapor barriers applied to the exterior of a home.

Installing Faced Insulation

• Faced insulation is installed with the insulation side against the exterior wall and the paper or foil facing toward the insulated space. For quick installation, hammer staples along the edge of the stud through the paper or foil facing using a hammer-style staple gun . The paper or foil has a long tab on each side that overlaps the stud for this purpose.

Other Places for Faced Insulation

• Faced insulation, besides going into external walls, also is installed under floors, above ceilings in attic areas, as well as in basements, knee walls and cathedral ceilings. To aid in vapor diffusion, sometimes homeowners choose to install paper- or foil-faced insulation in bathroom walls as well.

Vapor Diffusion Retarders

• While foil and paper-faced insulation works as a vapor diffusion retarder, this may not be enough protection against water vapor flow, especially if you live in a humid climate or have excessive HDDs. Use a polyethylene vapor barrier, a finely woven backing made of plastic, on above-grade walls and ceilings in regions with 8,000 HDDs or higher, according to the government’s Energy Saver’s website.