Tree, mine has that thin ply on ceiling and Roof
Thinnest stuff I’ve ever seen in large sheets ... and probably the cheapest too ... Probably imported for it’s “price point” ... I’ve looked everywhere but can only find “good" plywood that thin at Aircraft Spruce ...
Plywood from Aircraft Spruce But then they only carry aircraft grade ... the stuff in trailers is more like “pallet” grade ... (cheap) .. Hanging around at the RV repair shop, I saw only the cheap stuff used on even the Big MCs that were in for repair for leaks/Rot...
... all with various wallpaper looking stuff over it ... Probably only available from the RV dealer ... at a Premium...