Hi there. In Scarsdale, NY we've recently had our backyard deck, which was attached to the rear of the house, removed and 3 season "Florida" room built there. They did a good job and we're pleased with the new room, lots of windows, cathedral ceiling and well insulated. We'd now like to use the space underneath this room as a storage area for bicycles, gas grill, etc. but want to keep it as dry as possible. At present there is only a lattice type facade around the 3 sides which we'd like to keep for the look. Can I simply attach some XPS to this, from the floor of the room above to the gravel covered ground below, and then face it inside with plywood leaving a gap at the bottom so there's no contact with the gravel? The space will not be heated and we plan to leave the gravel floor as is. Look forward to any advice. Cheers and best regards, Rughead.