Well, yes, but you're in NC, not NY or Norway. We get a tad bit colder in our climates.
I saw, on my coop cam, my entire flock inside the coop just hanging out and preening yesterday morning after I finished chores. It was only 29F but they decided that is where they were going to hang out...
-15C isn't too cold.
But their utter avoidance of their coop during the day other than to lay eggs and not eating enough is disconcerting.
I feed half fermented/half dry Flock Raiser year round. I keep the ferment FR in a heated dog bowl so it doesn't freeze. You could try keeping some mash in a...