"Graeme" wrote in message ...
"adder" wrote in message
om...
"Graeme" wrote in message
I'm just aiming for a perfectly flat floor. Without some sort of
filler/levelling compound, the ply will show the undulations that are in
the
existing chipboard.


Here's what you do - get a circular saw, cut around the perimeter of
the bathroom floor, buy some WBP ply same thickness as the chip, cut
it to size and install in the hole you created. Job done.

A cunning plan!
Let me think about that one.


exactly. as you said initially you were advised to replace the floor.
The other bodges mentioned in this thread are recipes for trouble.

Expanding foam expands with remarkable force, as I found to my
consternation Sticking it under ply is obviously something the
recommenders have not tried. At least the results would give us all a
laugh

Tiles onto 6mm ply... come on be serious. Tiles need a _very_ rigid
surface. The thicker the wood flooring you use the better. I would
choose at a minimum 1". Grout between tiling edge and walls should be
silicone. If you want a perfect job I'd pack the top of any joists
that sag below the others.


Any kind of cement type filler used in the thinness suggested is going
to disintegrate. 6mm ply offers no rigidity or support. If the chip
floor's uneven the odds are its liable to move as well. That whole
ideas a total mess.


Regards, NT