Cuprinol on plywood before tiling??!

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My builder has suggested putting Cuprinol on a new plywood floor before tiling. Never heard of this before. Asked him if it would interfere with tile adhesive. He then suggested using pva to coat the wood afterwards.

Doesn't sound quite right to me (why not just get the right plywood in first place?), but I'm no expert. Any ideas please?
 
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I don't get it either.

Only guess is that the builder is of the old school who add preservative to all wood. (Does he ever use the phrase 'You know me, Belt and Braces')? Of course, if the grout or tiling fails and the wood gets wet it can make the difference between rotting the ply or not, but if you're that worried why not buy WBP?

Like I say, I don't get it. Maybe somebody else has a clue.
 
Definitely don’t do that; you should never use any primer before tiling unless the adhesive manufacturer recommends it, most don’t. You must only ever use WBP ply as a floor tile base (& never on walls) or the water in the adhesive may cause the ply to delaminate, what thickness is the ply? Is it a new floor or over boarded. As for using Cuprinol :eek: , that it will almost certainly affect tile adhesion. You should never use conventional PVA on a tile base either, it’s water soluble & will re-emulsify if it gets wet causing the tiles to fail. If you need to prime, only use an acrylic or SBR based primer/sealer. Only ever use a cement powder addy on floors & it must be flexible over ply.

I don’t think your builder has a clue what he’s talking about & he certainly doesn’t fill me with confidence, god knows what other little gems he’s got up his sleeve :rolleyes: ! Is this an extension your building or just refurbishment work? If its refurbishment, I’d strongly advise you replace him with a professional tiller who actually knows what they are doing! Have a read of the tiling sticky & through the tiling forum archive posts, it might prevent him & you making some potentially very expensive mistakes!
 
would agree with Richard 1000000 % here, your builder knows absolutely nothing about tiling, subtrates, primers etc.get yourself a proper tile fixer mate and save yourself the heartache
 
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Thanks so much guys. I'm no expert, but the whole idea sounded very strange to me. One thing I do need to check is the plywood, but I just don't know how to tell difference between WBP and other plywood. Any suggestions?

If I have missed anything else I'd love to know. Thanks again!
 
We've agreed to disagree about hardibacker on the walls around the shower and bath, but
Shower areas are to be tanked up with Bal WP1, before being tiled with Mapei keraquick (still debating about epoxy grouting).
You can of course tank the Hardibacker if you wish but it’s not really necessary, sealing & taping the joints is sufficient in all but wet room installations. Epoxy grout is a bit of an expensive extravagance here but, again, your choice.

One thing I do need to check is the plywood, but I just don't know how to tell difference between WBP and other plywood. Any suggestions?

Must admit didn’t know the answer to this one so did a search & found this old thread which should help;
//www.diynot.com/forums/viewtopic.php?p=352340

If I have missed anything else I'd love to know.
Be cautious with large format tiles, they require a flat base & extra care if they are to look good & using the correct adhesive is essential. Not sure where your fitting the quartz tiles but they will be very slippery when wet! You may need to use a stain inhibitor before tiling & most quartz tile suppliers recommend using a latex based adhesive which is a 2 part adhesive. Check with your supplier that the adhesive is compatible with your quartz tiles! You will need a decent diamond wheel wet cutter for Quartz tiles.

A few other pearls:

• Fill & tape the board joints before tiling; I use tile adhesive not silicone as not much will stick to it; spread too much silicone around & you could have problems, or use the manufacturer’s proprietary expensive sealer.
• Don’t grout down tiled corners or around shower trays, run a bead of silicone but after you’ve done the rest of the grouting.
• Prime the back & edges of ply with SBR sealer before laying; do not prime the tile surface unless your chosen adhesive manufacturer recommends it
• If using cement based adhesive, Gypsum plaster & plasterboard must be primed to avoid a reaction
• Never use PVA to prime a tile base or new plaster
 
Just out of interest, why is it advisable not to use PVA?
You should only use a primer if the adhesive manufacturer recommends one; most don’t; if you use a primer, it should be acrylic/SBR based which is not water soluble once dry. Standard PVA is water soluble, if it gets wet it will re-emulsify & there goes your tile adhesion; if it’s used in a wet area, the tiles may end up on the floor;
http://www.ultimatehandyman.co.uk/f...8&start=0&postdays=0&postorder=asc&highlight=

PVA is known as the plasterer’s friend, it helps control suction & provides a bond for new plaster over difficult surfaces but if applied over new plaster, your paint will not stick.
 
for quartz tile re:fixing

as rich said a "latex" based addy or you can use bal PTB.
 

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