To be clear, my coop will be above the present tractor run I already have. The Tractor dimensions right now are 13' long x 8'6" wide and 42" high. I need to start designing and building the coop before we get into the Fall. The Tractor is made out of steel, thus will hold the weight of the coop well. So far I know that I will probably have a separate module for the nesting boxes (thinking 3 good size boxes for 11 chickens) attached to the coop protruding beyond the rear of the tractor. The door for the coop will be on one of the sides. Thus at 42"high to start the base of the coop how high should I go up to make it comfortable for the chickens and accessible for myself to clean or attend to problems, and yet at the minimum height for appearance, cost of materials, and not making the structure look like a hi-rise or top heavy. Will most likely upload a pic of the run,so I can get some good suggestions. Location of the tractor is in the Chicago area, and temps at night are starting to get low. How low of temp before the chickens have to be in some sort of shelter? Thanks for any help.