I see that many of you are worrying about keeping your chickens warm. You do not need to worry about that. They keep themselves warm. You do need to give them wind protection. Wind and wet will make them cold, and sick.
To keep them dry, you need to measure. When the bird is roosting in the coop, there needs to be 12 inches above their heads, and 12 inches from the wall. There needs to be open ventilation above their heads EVEN IN VERY COLD weather. This seems so counter intuitive, mostly I think because we equate warm with closing up the house tightly. Think of being in a car in cold weather, with several people. Quickly the windows fog up, if you stayed there all night, by morning, you would be soaked with condensation.
Your birds are actually staying dryer, and therefore warmer by staying outside of those small coops!
Mrs K