It does depend on breed, some can fly better than others, my cochins and frizzle cochins can't get up on things like my d'uccle can, I have a three step roost, 2x4 with the 2 up starting at about a foot and each one is a foot higher.
Chickens, muscovy ducks, turkeys, donkeys , goats, dogs, bunnies, fish, parakeets, a parrot, and a cat.
We plan on breeding buff brahma bantatms if we can find a show quality trio similar size to bantam chochins. We will also have a couple modern game birds for showmanship. I am currently using a ladder system that is 4ft tall for my LF chickens. So maybe I will make one 8 ft long with three rungs at 1ft, 2 ft, & 3 ft high for the bantam coop. Plan on having room for 30 bantams. How high off the ground should the nesting boxes be. I was thinking 1 ft off the ground.