 So TREX Rain Escape does just that. It uses a network of troughs and downspouts to divert water away from the deck, and that protects the deck structure from rot and decay, and it keeps that space below very, very dry. Now, most drainage systems install below the joists of a deck, but TREX Rain Escape installs over the joists, so it protects the entire structure and also allows you to run gas and electrical lines just below the deck surface so you can power lights and appliances and all the other things you're going to put in your newfound space.