I'm having the same issue with my chicken pens. I have tarps over my big chicken pen, bc of chicken hawks. My husband refuses to help in any way, so everything is on me. He won't allow me to properly roof the pen. There is a run off that's tight behind my pen where water collects. If I feed my chickens in anything other than the containers or my chickens do their normal thing of scratching the feed, it gets moldy, especially after it rains.
I live in the central part of Georgia, around the Columbus area. We have very hot, humid & rainy summers...even if it's just a short shower here & there. My daddy's from Louisiana, so I can see why he & my mama chose this area...
I've thought about adding sand to my pen or pine shavings, but totally lost on that. I can dig around my pen if I need to...it's just the large money part that he won't allow, like for roofing or drainage projects. I can't buy gravel...
Any help would be great...I love my chickens & try to do everything in my power to keep them healthy & happy...they are my babies...