I live in NW Missouri where the weather gets 100 only a few days a year, and -degreze a few days durring the winter. I'm planning on building a pallet coop for 6girls. Will I need insulation in all the walls, or in the roof, both? Also we have tons of peanut packing styrofom and have access to tons more. Would this be a good insulator. I know I need to make sure there are no cracks where the girls can get to it.