Insulation in a coop, is a waste of time and money. A coop is not like your house, where it's totally closed up in the winter. It's open/ventilated to the outside (At least. it's supposed to be) What good does insulation do, in an OPEN BUILDING? Answer, absolutely no good at all. The chickens already come equipped with perfect insulation of their own, they really don't need any help from us to keep warm. With insulation, you will need interior walls. Otherwise the birds will happily shred the insulation. When you have interior walls, in a coop, you have just provided perfect housing for rodents, insect pests, and who knows what else. There was a post on this forum just last year, where somebody had insulation and interior walls in their coop. Well, they ended up with one heck of a rat problem. Do not bother with insulation, chickens have managed to survive for hundreds of years without it, and they will go on for hundreds of years more.