I am working on finishing my attic and am wondering if I can add to my current insulation between my rafters in the ceiling. The current backing on the insulation that is there would not hold additional unfaced insulation due to the weight. I do have some left-over paper vapor seal and some foil as well from the previous home owner. Can I re-face the current insulation myself? If so, how do I get it to stay on - a type of glue?