Chickens in all their hardiness have some very defined 'rules' for husbandry. Moisture is one of them, its just all around bad. Not talking when it rains. Damp and wet bedding may not necessarily cause an issue, but it is definitely an enabler for health issues from respiratory to feet. It is also an excellent way to grow all kinds of microbes you don't ever want around your birds or animals to include mold, parasites and other very life threatening baddies. Very rare to find a modern livestock operation with dirt floors, most states its against health code. I don't use a dirt floor as a lot like and prefer for my chickens, just have to much moisture at ground level in my area to even consider that as an option. I live in the woods so I have a very rich, black soil which is also full of chunks of granite and assorted minerals. Its also a great source for very cold frozen air. All my coops are at a minimum 2' off the ground with wood flooring covered in some sort of sheathing such as linoleum flooring or bath backing. Also why I don't use standard hay, leafs or un processed straw as bedding. It just holds, hides and grows moisture. Cheap and free isn't always best..works for some which is fine. Just doesn't work for me. I only use All Purpose Sand, Wood Shavings and Chopped Straw in my run and coop. These also have their individual pluses and minuses, just have to figure out what works for your location and try new things until you find that perfect combination or material that really works for you and your flock.
