Just my opinion, you can use branches, ladders or boards for your bantam and large chickens roosts. Roosts should be at least 2 inches to 4 inches wide. Chickens don’t wrap their feet around a roost like wild birds do. They actually prefer to sleep flat-footed. This has an added benefit of keeping their feet protected from frostbite in the winter using the roost as protection and using their body as protection on top of their feet. Also, this protects their feet from mice or rats who may nibble on chicken toes while they are sleeping. Hopefully there aren't any. I personally have all large fowl so I use 2x4's with the 4 in side up. I haven't had any complaints. 
