My husband and I are preparing to build a house in the Arizona desert. We have two large decks planned (approximately 20' x 16' each), one deck on the first floor with a crawlspace foundation (so no concrete slab), and the second deck above the first deck on the second floor. The upper deck will be partially covered. We are looking at waterproof flooring options (versus open decking), such as tile with a Kerdi-type underlayment, but we're interested in other suggestions.