I have 2 winter hardy breeds, buff orpingtons and speckled Sussex. They have a draft free coop with pine shavings on the floor using the deep litter method. I live in southeastern Pennsylvania where we don't really experience extreme temperatures in the single digits or negatives, but we do get temperatures below freezing like tonight, 28 degrees. I'm wondering though if the chickens are alright with what they have, and if there are any temperatures where I should consider closing everything off or adding heat?