The "poop board" is essentially a shelf that sits beneath the roost bar(s) to catch the waste expelled during the hours the birds are at roost. The advantage of having one is that it protects the floor space below from the accumulation of that waste since it represents a majority of the waste expelled by a bird in a given day and is expelled while the bird is in one spot vs. out wandering about during the day which allows that waste to be scattered. The amount of waste that can appear beneath a roost in just a couple of nights is often significant. For coops where the goal is to provide the most open, livable, space possible the poop board is a definite advantage. The downside, of course, is that the board must be cleaned periodically. I employ a poop board and have mine lined with a layer of PDZ which helps to eliminate odors and dries the waste -- it is as simple as cleaning a cat's litter box to sift the PDZ and discard the waste, takes me about five minutes for my coop. For my coop I have used the space beneath the board as a place to put my feed and water station - the feeder and waterer are actually hung from the poop board itself and the poop board keeps the feed and water clean by preventing any waste from falling down into them.
