Hi! Im about to insulate floor of my van with xps +plywood on top. I watch some videos and read some older posts but cause of overthink Im left with some questions. For example I saw people filling ribs space on van floor with xps straps. Do I have to do it? If yes or no, do I have to glue xps board to floor or its enough to just place it and glue plywood on top of xps? #lifestyle source