Frostbite is usually caused not so much by cold alone, but cold and humidity combined. One thing to check is if your coop is airtight. Chickens put off a lot of humidity with their resperation so even if it's really cold, they need air vents to release the excess humidity. Sometimes it's not the coop though, and is just the area you're in. Waterloo has a river going through it, right? If it's not fozen over, it might be kicking out excess humidity and there's not much to do about that except smear vaseline on combs and wattles and hope this freaking winter finally goes away.