To give you a clearer picture I'll explain a little more. We have two coops. One for the hens and attached to it is another for our six friendly roosters. Because a flock that had been free ranged on the same property was lost to predators,I in closed two car port frames with chicken wire. When The weather turned cold I in closed one port with the plastic. The grain bags that I used are very large and durable. It is designed to hold many ton of grain over winter. I have many bales of hay around the inner walls and have made places for the chickens to roost. The floor is not covered with anything, it's just dirt. There is a door that I open to give them the option of going to the other port for some fresh air. Having said all of that, I will double check for leaks, but other than getting a fan of some kind, I'm at a loss for quick solutions. In reply to free feather's comment, thanks, I will clean the sand out of the coops ASAP.