Chickens love to go to bed,when its airy,window to see, but safe.They often move around at night and need a few feet.Unlike birds they also need a flat roost1x4 or -1x6 ( the size they choose most),which could be near the bottom,then they could just hop up.To keep long feathers healthy,turnaround and head room is helpful.Could use wall hanging water and feed.Needs a nest inside,they lay eggs odd hours,and don't like more then one nest location.
No matter what geographical location,there's always many days they can't go out.extreme winds,rain,sleet etc.They would be scared out in these,would not lay eggs as well.Everyone needs a safe,comfy home.Albeit small,can work,just not tiny.