I am building a open coop/pen and need to ask a question. This will be a ladder type roost. The highest point of the roof will the roost will end, is eight and a half feet off the ground. How high up should I go with the last roost board? I am going to use 2x4s skinny end up instead of flat end. The main question is, how much spacing between each rung, for stander breed chickens? So they can get from the top to the bottom. They will have their wings clipped.