Tiling over new Plaster


Postby DCMartin » Thu Feb 12, 2009 9:40 pm

Tiling over new plaster.
I want to retile the bathroom, but have had to remove all the plaster on one of the internal brick walls as it was unsound. I intend to get a professional in to replaster this wall, and then tile over it. How long do I need to wait after the wall is plastered before I undertake this tiling? Also, I would like some advice on whether to PVA the walls before tiling, as I have seen a reply on the forum that suggests “Tile adhesive suppliers recommend that you shouldn’t use PVA to coat walls as it acts as a barrier between the wall and the adhesive. They advise applying a bonding agent to the wall prior to tiling.” If this is the correct procedure, what bonding agent do they mean?
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Postby stoneyboy » Fri Feb 13, 2009 10:14 pm

DCMartin,
Wait until the plaster is dry (no dark patches remaining), cross score the surface to provide a key. If you like applying the adhesive to the wall its probably worth coating the wall with waterproof pva, if you prefer buttering the tiles stick the straight on the wall.
end
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Postby rosebery » Fri Feb 13, 2009 10:28 pm

Ideally leave new plaster (bonding plus finish) 4 weeks to dry before tiling.

Dot and dab plasterboard with plaster skim can be tiled in 24/36 hours.

If you don't skim the plasterboard you can tile it immediately but prime it first with an acrylic primer like BAL APD or SBR.

Note that plaster or skimmed plasterboard can accept a max weight (tiles + adhesive + grout of 20kg per sqm. Unskimed plasterboard is 32kg. Check weight of your tiles before deciding the substrate.

Please NEVER use PVA unless you want the tiles to fall off - all that holds the tiles up is a thin layer of PVA. Use an acrylic primer as above - thats what they mean by bonding agent.
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Postby macten » Mon Feb 16, 2009 1:22 am

Why skim the wall?
Just tile to to the brickwork - excellent substrate and will hold more weight.
Skim can only hold 20kg/m2 and you'll have to wait for it to dry and it'll cost you for the spreader. If flatness is an issue then do as above and dot n dab PB.
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