Down spouts come in various sizes: 2”x3”, 3”x4”, 4”x5”, and custom sizes. Down spouts are figured and located, based on roof areas, long runs of gutter, roof pitches, trees, etc. It’s good to remember that the bigger the down spout, the more efficient it will be. For example, you can install a 10” wide gutter. However, if there is a small opening and water can’t get out quick enough, it will overflow!