When determining the size you will need for the birds. Is it soley coop size or do you factor in the run also? ie., if I have 20 chickens and each one needs about 4sq ft each that equals out to 80 sq ft total. If it is just the coop as I suspect, and decide to make 100 sq ft total for the birds would it be more wise to make 2 smaller coops opposed to 1 larger one? Like 2 5x10 coops and a run in between to connect them. I am planning on making at least the run out of PVC as I need this to be a chicken tractor and have the costs low as possible.