So i got my new 30x40 pole barn up and im planning the insulation, i have 80 sheets of this stuff pictured 1.5” thick ( i have no idea what it is) was debating using it on the walls double layered. What ya think? I only want to do it once, think this stuff would be good ? And if so should i cut to fit between the wall girts and behind posts or just right on the girts