I would also add that you should perhaps cut a smaller door just for the chickens to enter and exit and a way to close up those windows because once it’s -40 and blowing snow your babies will be COLD and chickens do not like snow or cold.
I’m newish to chickens on my own but I know that growing...
I built mine with insulation inside the walls and I put up some vapour barrier with wall panels over top and added corrugated plastic on top (it’s cheap and it’s plastic so I can spray it down easy enough but haven’t needed to do so yet.)
You could add some holes in the walls and put in small...