There are only 3 things that will ruin your deck over time: water, water, and water. A dry-below is the most practically useful addition to a deck. In addition to preserving lumber indefinitely, many homeowners add a dry below to use the waterproof area under the deck to store things that have been cluttering their garage. Often, homeowners will request one to maintain the usefulness of a seating area underneath a deck. It also allows for electrical work throughout the frame, such as a ceiling fan, or recessed lighting, and of course, very often includes a ceiling to make it into an aesthetic masterpiece. We prefer to use DekDrain rubberized trenches, and have never been called back about a single leak.