I live in northern Minnesota where temps can get as cold as -30f I built a 4x4 coop and insulated the walls,floor and roof. I have a window in it that i keep cracked and a small slidind door that is always open. I want them to lay all winter. I have a heat lamp in there and it has been keeping the coop about 60 degrees all of the time. It has been freezing at night now.have I gone overboard with the insulating? Also how do I keep them laying all winter? Do I need to cover the run for the winter too?