Winter came early in parts of Michigan this year and so did the frost. Our temps are yet in the mid teens and have yet to drop below the freezing mark. We recently converted a premanufactured wood shed into what we will use as our breeding coop. Currently we have our future meat bird breed in there with their husbands to be. 10 birds total in an 8x8ft. barn style storage shed. I insulated the half walls but not the ceiling. The floor is wood and sits on a 4x4 foundation. I cross ventilated it at the peak level running from west to east as our wind direction usually comes from. It is actually pretty comfortable in there with the door shut. I have 4 roos in that getup and already they have black spots on their combs! Iam going to blame this on wet head syndrome as I call it. We had a lot of off and on rain one day with a major drop in temp at night. The birds got soaked throughout and their heads were wet when they went to roost in the evening. Moisture freezes when it hits cold air. Because a chickens urine is in its feces, that moisture accumulates within the coop area and into the air within. Very important to ventilate it out and keep the coop cleaned of feces buildup on a regular basis. Daily cleanup in the morning is best after a nightlong of perching on roosts. Hey! They get comfortable and this is what they do at afterhours. This process along with a bit of vaseline rubbed onto their combs may help to lleviate frost bite this winter.