I think this is similar to some "stuff" I used years ago on a '77 Westy. It wasn't roofing material, but heat/ac duct wrap. It was foil on one side and sticky on the other, with about 1/4 inch foam. Since I was painting this Westy and doing a color change I had it stripped down to a bare shell. I filled the ribs with the expandable foam in a can, sprayed 3M rubberized undercoating between the ribs, then covered everything with this stuff, including the area under the fold out bed. The result was an air cooled bus that was so sound-proofed that I could barely hear the engine at highway speeds. It was eerie compared to what it was like before.

Jeff Stewart

----- "Roger Whittaker" <rogerwhitt1@GMAIL.COM> wrote:
> dear shiny side out
> "this" at Lowes ... "the stuff that was discussed"
> everyone seems to be in the know but moi ...
> what is "the stuff"
> yours