Kraft Faced insulation is manufactured with an integral vapor retarder. The kraft facing includes attachment flanges at the edges that are used for either face or inset stapling. The kraft facing, applied with asphalt to the fiber glass insulation, has a vapor transmission (permeance) rating of one perm or less.
Unfaced insulation is manufactured in increased widths to permit friction-fit installation in wall cavities. This insulation is used with a separate vapor retarder or where a vapor retarder is not required, and allows you the flexibility of using a separate vapor retarder of your choice.