Hello

I am a little confused as to what tile adhesive I should be using.

I am thinking of 300mm * 600mm tiles in either ceramic or porcelain.

I am tiling mostly on to a plywood 'box' I am building from WBP ply (and a little onto skimmed and then painted plaster board- only one row, weight taken by WBP plywood box, i.e. upstand at sink/toilet back). Tiling is in bathroom, on a 'dry' wall.

'Wall' tile so need good grab.

I have come across a few tub adhesives which say they can do 300*600mm tiles but when I contacted their technical department, he suggested that because the adhesive were on WBP ply, the adhesive wouldn't be able to dry out. I can see his point because the WBP has waterproof glues which would impede the moisture drying out.

I was thinking about Mapegrip Plus..but now I am not so sure.

So what type of adhesive should I be using? one that relies on chemical reaction? rather than moisture drying out.

The powdered adhesives usually come in big bags and I only need to tile approx 2 square meters.

I've also noticed some powdered adhesives costing £50/bag

Also I've seen contradicting information RE whether or not to prime the WBP and skimmed, painted wall.

....And thus, I am confused

I live in the Middlesbrough area, so Topps, CTD, Tile Giant near by.

Advice welcome.

hi the techies are right tubbed addy wont go off but its not to do with being on ply, its the way tubbed dries through dispersion

tubbed is unsuitable for that size tile whatever the substrate

As per Mike, tubbed adhesive is no good for tiles of that size and definately not porcelain. As for priming the ply, that will depend on which manufacturer you choose for your adhesive. If you only have a small area to do then you can get 10kg bags of Mapei Keraquick which would be suitable for you. If you are using powdered adhesive then plaster based substrates should really be primed with and acrylic or SBR type priming product. What is the wall painted with, emulsion or gloss paint?

Shouldnt need to prime ply with keraquick either...

I've downloaded Mapei's datasheets for the Keraquick and Keraflex (as these are both available at Screwfix in small bags).

from what I can see, the Keraflex says it can be used to bond to:
'interior painted walls, as long as the paint is firmly ancored'

The painted section of skimmed plasterboard that I will tile (to a height of 1 tile, i.e. splashback) is painted in specific bathroom paint (i.e. Dulux moisture resistant bathrrom paint).

Neither Keraflex or Keraquick seem to mention tiling to WBP plywood or what preparation would be necessary (priming).

As stated, Keraflex says it can be used to bond to:
'interior painted walls, as long as the paint is firmly ancored'. Then it says application to gypsum must have Primer G. I'm not too sure what a primer would be doing it the skim is already painted in moisture resistant paint.

Keraflex looks like it ticks more boxes for my application than Keraquick. Although, being new to this, I could be wrong.

Thank you for your responses by the way

bathroom paint will have to be sanded before tiling as the surface will repel mositure

[QUOTE=pe+e;344861]I've downloaded Mapei's datasheets for the Keraquick and Keraflex (as these are both available at Screwfix in small bags).

QUOTE]
primer g is cheapest there too

'Faithhealer' - Do I need Primer G? According to Mapei spec sheets, Primer G is for Gypsum- but I cant see what it would be doing on painted gypsum because the paint (bathroom paint) will be sealing it anyway.

Would I need to prime the WPB at all? I've noticed some mention to prime the back of the ply- what would this be doing??

Do you guys think Keraflex would be better suited to the combination of substrates (WBP plywood and skimmed plasterboard) I've got.

thanks again

Just thought I would update...

As per Mapei's black book (and Mapei's technical help),....and the above information of course!... I used Keraquick. I didn't primer the ply (as instructed no need to) and as the paint was 'well suck' I just roughened i up with sandpaper and didnt prime that eiher.

Tiles are stuck on and all looks good. Just need to grout now...got a box of mapei colour plus at the ready!

thanks