sm_jamieson wrote:
I am making a soundproofing partition just inside a bathroom brick
wall, not attached to it, and to save space, the partition is to be
solid 18mm plywood with no battens. Wall area is only about 2.5 x
2.5metres.
I want WBP plywood, but I can see softwood and hardwood ply at very
different prices. I need the plywood to be very stiff since no
battening is involved. It also needs to be very flat, and to not warp
or bend, since it will be tiled on. I may also clad with a cement board
before the tiles. What's the best ply to use ? Good suppliers ?
Cheers,
Simon.

Use Fermacell board for soundproofing, rather than messing about with
trying an unconventional ply construction.

dg