PVA


Postby max5445 » Mon Apr 14, 2008 11:39 am

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
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Postby rosebery » Tue Apr 15, 2008 12:29 am

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.

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Postby max5445 » Tue Apr 15, 2008 10:52 am

The wall is concrete and plasterboard
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Postby rosebery » Wed Apr 16, 2008 9:50 pm

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.

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Postby max5445 » Thu Apr 17, 2008 8:47 am

many thnks
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Postby chris_on_tour2002 » Fri Apr 18, 2008 12:58 pm

rosebery - why not PVA?
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Postby rosebery » Fri Apr 18, 2008 6:26 pm

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.

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