I am planning a coop with a shingled roof. The coop is not that tall... a bit over 2 feet at the sides and nearly 4 at the peak. My plan was to use asphalt shingles on the roof, but what about the roofing nails that will be sticking through? Do I need to worry about the chickens hurting themselves on them? Any suggestions for an alternative? The picture isn't quite to scale - proportions are not right... the run is actually taller than the coop.