Chicken Co-op, Vapor Barrier

[Trochu]

I've got a question for the group. I'm setting a record for the world's longest chicken co-op build. The shed is built and tin has been ordered and is scheduled to arrive soon. This structure will never be heated but I am planning on insulating it. As it's a chicken co-op, there will be quite a bit of moisture inside and out and the door will be open most of the day, to allow the chickens in/out. Should I be installing vapour barrier on both sides (inside and out) of the insulation, just inside, just outside, neither, underlay for the roof? I'll be installing a vent for the attic, just not sure how necessary all the other stuff is as it will never be heated and open a majority of the time.