You get much more controlled results if you make the mesh from scratch, which is what I always do. Maximum control = a better final product. Boolean is good for certain things, but I wouldn't recommend it for a roosterpit. A better approach would be to start with the floor and build up the walls around it, putting the roof on to top it all off (heh). If you're trying to cut a roosterpit out of a solid shape, similar to how an old Native American canoe might have been made, you're either A) in for a very long process in order to get anything usable, or B) going to end up with something clunky and ugly.