I have a 2-story building that I will be using as a garage/workshop (NY). The 1st story is concrete block and the 2nd story is wood-framed with TYVEK and vinyl siding. There is no heat installed but may do that in the future. I have the opportunity to buy R19 fiberglass insulation for the 2x6 walls at a great price but it is unfaced. My question is - can I use plastic sheeting or maybe TYVEK as a vapor barrier for the 2nd story workshop? Or are rolls of kraft paper available? What would you suggest?