Insulation, in a coop is a total waste of time, and money. What good does insulation do, if you have a well ventilated coop (As you should, even through winter). Answer, absolutely none. I have an open-air Wood's coop. The whole front wall, is wide open year round. There is no insulation, and no added heat, of any kind, outside of what the birds generate themselves. And the temp of the coop is usually 10 to 15 degrees higher, than the outside. That's with NO insulation. So that blows the myth, that you need insulation to achieve higher temps in the coop.
When you insulate a coop, you have to install interior walls. Otherwise the chickens will shred, and probably eat the insulation. No good. And when you add interior walls, you give rodents, insects, including mites, and really, who knows what else, a nice hidden place to set up house for themselves. From where they can come out and harass the chickens. Bottom line, unless we are talking about some kind of thinly feathered, exotic breed, they are more than capable of handling cold temps. And they really don't need any "help" from us. Give them a well ventilated coop. Not a wind tunnel where they'll be blown all over the place. Ventilated, for max air exchange, and they will be good to go.