My coop is 12x8 my run is 12x20. The coop floor is concrete but I need to put something on it for warmth and to keep it dry.It has some sand down . Also want to put something in run to keep it from being to sloppy and help keep feet dry. I use pine shaving in my nest boxes. My 4 mt. olds scratch straw out of nest boxes and break the eggs. My 8 mth olds don't care whats in the boxes.