i live here in alaska where it commonly gets as cold as 14f :|
i've never had a problem with it, and i don't think i've ever had any problems with frostbite until 20-30 below zero. only by biggest roo got some frostbite on his comb, and i dubbed it and never had the problem again. if it does get that cold in winter where you are, you might want to give them a slightly wider perch so that their belly feathers cover their toes and keep them from freezing. but then again, i've only ever had the more cold-hardy breeds.
when it gets that cold, you should give them some extra heat, at least a light bulb put low in the coop, but not so low that they can rub up against it and get burned. a heat lamp, even, but that should be set higher up to prevent fires.
but yeah, it's been much colder than that here and i haven't had too many problems. they lay right through the winter with no problems at all
i even got a heated water bowl, because at those temps you gotta worry about water freezing.
another thing about when it gets colder, the birds will need more energy that normal to keep themselves warm. lots of leftovers, some scratch every day will keep them nice and happy