Hi. I am in MI. Last year it got mighty cold and my ladies got frostbite on their crowns...okay so here's the question. They perch on rafters where air comes in under eves(for vetilation) Their coop ..a 10x16 room has straw 2 bails thick on ground. Ive made lower roosts but they like the 2" rafters. Any suggestions on keeping humidity low...it currently goes to 70%...and get the ladies to use lower perches?