For the most part, unless you have a heat source inside of the coop, insulation of the walls and roof is not a big factor. Yes a few degrees may be the small difference from the outside temperature; but, the main factor is to maintain a comfortable temp for the girls at all times. First and foremost blocking the extreme cold air entering the coop is important. If the North and NW side are open, any blocker made of wood, cardboard, or plastic material, should be attached to the coop from top to bottom. Some folks like to drape fabric or plastic sheeting on the other open sides. Depending of the size of the coop; one or two 250W infrared heat lamps attached to the roof keep the hens warm. If the temp is freezing or below, keep on 24/7 and when at 40 or above keep on from dusk to dawn. The floor acts as an Insulation in a way. If the floor has a mix of shredded paper and hay over the dirt sub-floor, it absorbs the heat from the lamp/s and keeps the hens warm. Heat rises, thus the upper levels where the hens may nest or roost will be warmer than the outdoor temperature by several degrees. I used some black plastic from a trash bag and wrapped it around the water fount and that absorbed the heat from the lamps, keeping the water from freezing. No Smell: I spread ample PDZ on the floor to absorb waste material on the hay/paper shedder materials. Worked like charm. AS for Insulation material being applied to interior walls of a coop; my heating contractor said it was not a productive thing to do. In the summer heat is retained and the inside temp gets very hot, and in the winter; unless you have a method to heat the inside; the insulation will help retain the COLD making the coop colder. Thus insulation in the winter (without heat lamps) is a waste of time.