On either side of glass roll insulation, there is a one inch edge of folded over Kraft paper that extends beyond the edge of the fiber glass roll that is used to staple the product to the stud. I prefer not to staple this paper edge to the face of the stud as it makes it more difficult to install the drywall. I usually staple this paper edge to the inside edge of the stud making the face edge of the stud completely visible. This also makes for a better seal or air barrier when installed this way. Additionally, there is an approximate 1 inch thick air pocket created between the kraft face of the insulation and the back of the drywall. My question is: When insulation is installed that has a kraft paper or foil face vapor barrier, does adding a 6 mil. poly layer on top of the paper insulation behind the drywall create two vapor barriers that may cause a problem? Remember also, that there is a one inch thick air pocket between the poly and the Kraft paper as descibed above due to how the insulation is stapled to the side face stud.