I'm going to have a 2x4 for their roost. How high off the floor should I have it? How high can I expect them to hop/fly to get up there? There won't be any kind of ladder. Or should I have some ladder for them? I have all standard chickens, some larger breeds. The roost will be 7 feet away from the nests, and the top of the nests will be 24" off the floor (2 stacked on 2, all 12x12).