Insulation in a chicken coop is a waste of time and money. There was a post a few days ago, somebody with an insulated coop, had found that rodents had set up house within the walls. And that's all you are doing, is giving mice, rats, or who knows what else, a perfectly hidden space/housing, from where the can come out and harass your birds, and eat their feed. Worry more about proper ventilation/fresh air flow, then insulating and heating to "KeepThemWarm". Unless you have some kind of thinly feathered, exotic breed, they don't need any help from us to keep warm. You are doing those birds no favors at all, maintaining the temp above 0-C (32-F, which is nothing to a chicken). Lose power, and those un-acclimated birds will suffer then. And it's senseless.
I've had temps below 0-F, not including any windchill, and my chickens thrive. And that's with the whole front wall of the coop open, covered only with hardware cloth. No insulation, except for what God gave them. And it's a walk in, stand up coop (A Woods) People make the mistake of putting their own human limitations with the cold, on an animal, that is more than properly equipped to handle it.
I've had temps below 0-F, not including any windchill, and my chickens thrive. And that's with the whole front wall of the coop open, covered only with hardware cloth. No insulation, except for what God gave them. And it's a walk in, stand up coop (A Woods) People make the mistake of putting their own human limitations with the cold, on an animal, that is more than properly equipped to handle it.