purlins

Title pretty much says it all. Do I need to have vapor barrier on plywood, purlins, then foam closure strips, and then roof? Or will birds do just fine with just the metal roof on purlins. It will have very good insulation as it is a Woods Open air coop. Thanks in advance for any answers!

Hello all. I've taken on the task of building my own chicken run, which you would find amazing if you knew me :D (no carpenter skills). I started last weekend. I have the foundation/walls all standing and I'm staring at the roof and thinking I would like to really predator-proof it, so...