I am building a coop now that will be about 4 foot by 5 foot with a 8 foot by 8 foot run, for 6 chickens. They will free range during the day when we are at home. We live in Wisconsin where sometimes it gets to 20 to 30 Fahrenheit below at night in winter. But mostly around 0 most of the time. So do i need to insulate my walls? Or is this just overkill? The north side of my coop is against a shed. Thanks for all the help!