2018 gulfstream 30 friendship travel trailer. The roofing plywood under the rubber membrane is starting to buckle. To inspect the problem I have cut a small hole in the membrane to evaluate what the issue is-there are no screws or hardware holding the plywood down at the joint to the next plywood; also there is no structural framing at the edge of the plywood for the plywood to attach to. The plywood is unsupported at the back edge across the trailer for some distance until it gets to the next beam going to the front of the trailer. This problem is on 2 joints running the entire width of the trailer. User's recommendation: Do not purchase.