If you go to the lumber yard and tell them you want plywood clips, the kind
used in roof sheeting for houses. They are very thin alumunim and come in
different sizes for different size plywood. The other choice is tongue & groove.
I welded a piece of steel down the center, as you cannot put one piece of
plywood, and get it under both the sidewalls at one. If you want photos of how I
did ours, contact me off list and I will send you what pictures I have.
I suppose you could contact Airstream directly, and find out what they
suggest for an r factor. I put rigid foam under the floor of the Crusette. It
comes in 11/2 and 3 inch I think. The lumber yard will have this also, and tell
you the R factor of each. It is foam core, with foil on both sides, and you can
cut it witha large knife, to shape it in between the frame ribs.
Hope this helps,
Chuck & Lynn
1965 Overlander
1940's unknown