Unless you have some exotic, thinly feathered breed, insulation is a TOTAL waste of time and money. Chickens already come equipped with perfect insulation of their own. They don't need any help from us, at all. Just give them a dry, WELL ventilated (Not a wind tunnel) place to live, and they will be totally fine. The only thing insulation is good for in a coop, is to give rodents, a nice and cozy, well hidden place to live.