I am planning a coop with a totally enclosed run. I live in the middle of a large city, so I do not have a problem with many critters like some of you have. I notice that most have a coop door that is shut at night when the hens are in the coop. I was planning to include a door, but is one really necessary? Seems to me the hens can go in the coop or roost in the run at night if the door is left open. Is there a real reason to keep the hens in the coop at night, if predators are not a problem?