I used some of this some years ago in a summer place in the Poconos. I
put it on over conventional dry wall. Even with LOTS of panel cement
and nails, still had some problems with moisture causing buckling. Make
sure to leave a little space between panels for expansion. Run a stripe
of black paint/stain down the joint before you put the panels up, or
you will see the dry wall. On the outside walls, the dry wall had
insulation behind it. It was pretty thin stuff.