Piloon the insulation in the bag type I have seen that used in metal buildings, and I figured that if that was how the commercial people did it an adaption of it should work for the home owner diy project. That is how I did my metal building on the sides plus I stapled the sides of the sides shut over the studs. When I did this I also reinforced the entire building and if I have problems in the future I am going to replace the sides with chip board and then vinyl siding. When I do that if I have to [ hope not ] I will take out the double vapor barrier.