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PVA
Posted: Mon Apr 14, 2008 12:39 pm
by max5445
Someone has mentioned to me about a substance called PVA, which is painted onto your wall prior to tiling, can anyone confirm that this is the case. many thanks
Posted: Tue Apr 15, 2008 1:29 am
by rosebery
That'll be fine if you want the tiles to fall off in due course!
What is the material you are tiling onto? Your answer will determine whether it is necessary to prime first or not.
Cheers
pva
Posted: Tue Apr 15, 2008 11:52 am
by max5445
The wall is concrete and plasterboard
Posted: Wed Apr 16, 2008 10:50 pm
by rosebery
Presuming you mean plasterboard is the top surface with concrete underneath?
You can tile direct onto plasterboard using a self priming adhesive like multifix.
However I'd recommend priming with an acrylic primer like APD first. Please DON'T use PVA though. Sorry if my last post was a little condescendng.
Cheers
pva
Posted: Thu Apr 17, 2008 9:47 am
by max5445
many thnks
Posted: Fri Apr 18, 2008 1:58 pm
by chris_on_tour2002
rosebery - why not PVA?
Posted: Fri Apr 18, 2008 7:26 pm
by rosebery
Chris
Because it never really sets and doesn't penetrate the plaster thus forming a thin skin on top of the plaster.
When the moisture from the adhesive hits the PVA it becomes live again and full adhesion of tile to wall will not be attained.
Thus all that is holding up a significant weight of tiles, adhesive and grout is a very thin layer of PVA which not surprisingly sometimes has difficulty holding it all up and voila - it gives up and the tiles are all over the floor.
If not using a self priming adhesive it's far better to use an acrylic primer.
You'll find a much more scientific answer on one of the ahesive manufacturers sites. My memory (failing) tells me it's the Ardex one but I could be wrong but in any event it's out there all the same.
I'd rather not take the risk, frankly.
Cheers