On Feb 23, 5:56*pm, wrote:

*Your "floating" floor is stronger than the XPS - building
"partitions" on top of the floating subfloor is standard practice.
Better than using PT wood on concrete.- Hide quoted text -


My subfloor *IS* XPS (5/8" OSB laminated to 1/2" XPS)! They're built
in 2x2 panels, and the manufacturer recommends 1/2" gap to surrounding
walls.

Concerning building partition walls on top of the floating subfloor:

1) Won't the walls move as the subfloor expands/contracts (why the
1/2" gap required around the perimeter?).
Seems like it would break lots of plaster joints.

2) Alternately, if I secure the partition walls through the subfloor
to the concrete below (creating a 'fixed' wall), wouldn't I be risking
that the floor expand and then buckle? I've seen this happen with
laminate (finished) floors that were installed too close to a wall.

3) Admittedly, there would be a lot less work installing the floor
first. Might be a lot more work if I ever need to remove portions of
the subfloor.