DIY Related: Have coated WBP ply with PVA - what to do?

[DadHelpingSon]

Hi all. As name implies Dad is helping Son with renovating his flat. I built a new wall in the bathroom from WBP ply. Plumber (yes I know, why listen to him) suggested coating the ply with 3-1 PVA. I then used Mapei D1 adhesive. Some tiles are coming loose - fortunately have not done too many yet. Mapei say I shouldn't have used PVA and to sand it off. The forums all confirm not to use PVA. It would be a massive job to sand it all. Is there a product (eg primer) I can apply over the PVA? BAL SBR is mentioned a lot - will it go on top of PVA? I can use another brand of adhesive as the shop will take back the uniopened tubs of Mapei.

Also, I need to tile-on-tile on the kitchen floor. Existing tiles are sound. What prep & adhesive?

[Colour Republic]

You better sit down as i'm guessing you won't like the replies just about to come... sorry

[grumpygrouter]

Hmm ply in a bathroom.... not a good idea! You may be as well to overboard it with tile backerboard and tank it (waterproof) in the wet areas and plasterboard in te dry bits and then tile onto that. Other than that, removing the PVA will be difficult....

[grumpygrouter]

What tiles are you looking to fix?

[Ajax123]

Over board it with 6mm Hardibacker perhaps......

[jay]

ohh dear as above and what size tiles

[DadHelpingSon]

Tiles are bog-standard "Flat white gloss" 25x33 from Tile giant. Overboarding is not an option as the wall is hard against the bath (which has no room to manoeuvre) at one point so I can't increase the wall thickness without demolishing it and moving it. I'll just have to re-treat the wall somehow whatever it takes.

[grumpygrouter]

Tiles are bog-standard "Flat white gloss" 25x33 from Tile giant. Overboarding is not an option as the wall is hard against the bath (which has no room to manoeuvre) at one point so I can't increase the wall thickness without demolishing it and moving it. I'll just have to re-treat the wall somehow whatever it takes.

Out with the sander it is then! You may want to try to wash as much off first as you can but don't soak the timber then sand it when it is dry.
33x25 tiles are too big for tubbed adhesive anyway, you need to use powdered stuff really.

[jay]

might be worth a read http://www.google.com.au/url?sa=t&so...FV1veR0I7nOWyA

[DadHelpingSon]

Tiles are bog-standard "Flat white gloss" 25x33 from Tile giant. Overboarding is not an option as the wall is hard against the bath (which has no room to manoeuvre) at one point so I can't increase the wall thickness without demolishing it and moving it. I'll just have to re-treat the wall somehow whatever it takes.

[Dave]

Sand the ply to create a key, then SBR neat.. Tile with a S2 adhesive.. job done.

[DadHelpingSon]

Thanks all. I'll wash it and sand it. Can I or should I also then use the primer? cost is not the biggest problem here, rather try to get the job back on track. Tile shop suggested Mapei D2 might be better (willing to take back the D1).

[grumpygrouter]

D2 is still a premixed adhesive and isn't suitable for your installation and your tile shop should know better. Use Mapei P9 instead. Oops, wrong adhesive, not really suitable for ply walls maybe Keraquick and latex plus!!

[DadHelpingSon]

Sorry, replies crossed over, Will sand as suggested and use S2.

[Dave]

Also use CG2 grout.

[Daz]

I would bin the plywood walls and replace with Aquapanel or equivalent cement boards. Then tile with a flexible cement based adhesive.

[RichieRich]

Yep exactly what Daz has said for a proper job. Some Tile suppliers are terrible for that. Recommending the wrong adhesive and grout etc for certain tiles/jobs. They should know a hell of alot more. Not good enough. Flexible powdered adhesive all the way.