We live in Northern Maine and have five 18 week old pullets. We have a 5x5 coop with an attached 5 Ft. X 15 Ft. run. We don't allow them to free range due to loosing MANY chickens to predators. When we first put built the run it was built on grass but now it's dead grass which turns to mud when it rains, but dries out quickly. As the long winter approaches my plan is to tarp the run and put a Corrugated PVC clear roof on for them to enjoy during the winter. I had purchased sand to put down for the floor, but now I'm second guessing that decision. I had made that decision because in the past when we've had chickens the ground would freeze at night and then thaw some when the chickens walked on it which caused the floor to get muddy and wet, which led to their feet getting muddy and wet in freezing cold temps. Any input would be greatly appreciated!