A coop should provide about 4 sq ft of floor space per bird, and you should subtract space taken up by feeders, waterers and nests. They need 1 linear foot of roost space per bird, and 10 to 15 sq ft of space per bird in the run. These dimensions will help cut down on or eliminate bullying, pecking, fighting, feather plucking or even cannibalism, which can occur in crowded conditions. It's best to have at least two feeders in the run, a good distance apart, and not visible from each other. Provide "clutter" in the run, in the form of objects the chickens can hide behind or get under or on top of, but not get trapped in. Examples are chairs, tables, pallets leaning against fences, etc.