I am trying to design an affordable chicken coop, but I am not a builder. I am not sure the correct way to do things. I have a couple questions. Question 1: If I am going to use corrugated tin on the roof, do I have to use plywood underneath it or can I just lay it over a frame of 2x4s? Question 2: I live in south eastern washington. We are considered desert. In the winter it usually gets down to the teens or 20s during the day in January or Feb. The rest of the winter is usually around 32-40 degrees. I want to get 4 Rhode Island Reds. Do I need to insulate my coop or will they be okay in a 4X4 coop? The reason I ask is because I saw someone in Parma, ID selling chicken coops and none of them are insulated. The weather in those parts is pretty similar to here. I also read somewhere that you should keep the windows wide open even in the winter? What do you think? Thanks in advance. I have never had chickens before so any help would be greatly appreciated.