Hi Flower,
I have poop trays under my roosts. They are 2' wide x 2" deep. The roosts are 18" above the tray, exactly across the center of the tray. I absolutely think this was one of the best, if not the best idea I have picked up while browsing BYC. I have 8 hens and 1 rooster and it takes me about 10 minutes with a kitty litter scoop and bucket to completely clean the entire tray. I have very seldom seen any tracks in the PDZ, however, but occasionally an egg or 2 has been laid in them. Absolutely no odor ever. I use the deep litter method over epoxied wood floors, sprinkle PDZ and stir around occasionally, and toss mealy worms on the floor for the chickens to keep the litter turned. Never, Never any odor. Probably more information than you needed or wanted, but compared to my other chicken coop, a couple of years ago, it is a pleasure to open the door to this improved method.