What Adhesive for Ply & Plasterboard

[microkid]

I really hope someone can help me out here as I’m going round in circles driving myself (and my wife) mad!

I am just about to tile our bathroom (floor to ceiling) and this means tiling over various different surfaces from old to new. These include marine grade ply, plasterboard, plastered brickwork and paint plasterboard (thankfully not much of that!).

The ply and plasterboard is fixed to an intentionally over engineered frame and secured at least every 200mm. There is no movement in this at all.

My tiles are nothing fancy plain white 250 x 400mm ceramic wall tiles.

So my question is what adhesive should I use? And what treatment should I apply to the walls?

The last time I did this at another property (10 years ago) I had no tiling experience. So I asked a work colleague how to tile over ply & plasterboard, he said Unibond PVA the walls and use Unibond ready mixed tile adhesive for showers (all bought from B&Q). Which I did. I had no problems and its all still there. The one time I had to take a few tiles off the plywood, I nearly broke my chisel.

However looking about online people say do not use PVA on ply before tiling, do not use Unibond. But confused because my experience showed it worked really well. So I have been looking at BAL & Mapei but totally confused about what to use?

Also with time being at a premium for me I like the idea of having a ready mixed adhesive so I can fit a bit of tiling in as and when I can and also I won’t have to buy or hire a mixer.

I will be tiling about 19SqM and then probably no more tiling for at least another 10 years!

Thanks!

 

[Karis]

I am just about to tile our bathroom (floor to ceiling) and this means tiling over various different surfaces from old to new. These include marine grade ply, plasterboard, plastered brickwork and paint plasterboard (thankfully not much of that!).

The ply and plasterboard is fixed to an intentionally over engineered frame and secured at least every 200mm. There is no movement in this at all.

Even marine ply (& WBP is all you need) is not a suitable tile base for walls & is totally unsuitable in wet areas. You should use a decent tile backer board such as Aquapanel which remains dimensionally stable in damp conditions, Play will most likely curl (especially if the back isn’t sealed & your tiles will end up on the floor.

My tiles are nothing fancy plain white 250 x 400mm ceramic wall tiles.

What thickness are they? Plaster has a maximum weight limit. You will also need a very flat tile base for that size tile & use a solid bed trowel, thick bed if the tile base isn’t perfectly flat.

The last time I did this at another property (10 years ago) I had no tiling experience.

So I asked a work colleague how to tile over ply & plasterboard, he said Unibond PVA
the walls and use Unibond ready mixed tile adhesive for showers (all bought from B&Q). Which I did. I had no problems and its all still there.

However looking about online people say do not use PVA on ply before tiling, do not use Unibond. But confused because my experience showed it worked really well.

You’ve been lucky IMO; trust what you’ve been reading, never use standard PVA as a tile primer especially in a wet area, if water gets in your tiles will end up on the floor. You won’t find many experienced/pro tillers using that stuff; it doesn’t have a particularly good reputation. Only use a quality trade tiling products suitable for your tiles & tile base, cheap DIY products are mostly crap.

So I have been looking at BAL & Mapei but totally confused about what to use?

I use BAL; trade Mapei will also do a good job but don’t use the Everbuild branded one they sell in B&Q, it’s not the same & specifically tailored at the DIY market. Webber is another will do a good job & there are others.

Also with time being at a premium for me I like the idea of having a ready mixed adhesive so I can fit a bit of tiling in as and when I can

Tub mix is evaporative cure & not suitable for that size tile, you will have initial adhesion problems, it will take an age to set & in some cases never sets at all & the tiles have to be removed to start again; you need a powder cement adhesive. You will need a flexible adhesive for any plasterboard or other panels; standard will do the rest but depending on how much you need you could use flexy adhesives over the lot. You can use a Rapidset mixing up small quantities at t time (no more than 30-40 minutes) but if the pot life frightens you use a slower setting adhesive with longer pot life. Plaster & plasterboard must be acrylic primed when using cement based adhesives to avoid a reaction with gypsum. Make sure your tools & bucket thoroughly cleaned between mixes. I would strongly advise you loose the ply & replace with a cement based backer board.

also I won’t have to buy or hire a mixer.

Assuming you have an electric drill, all you need is a paddle mixer, costs less than a tenner!

I will be tiling about 19SqM and then probably no more tiling for at least another 10 years!

If you use the wrong materials or incorrect prep, you will most likely be re-tiling in much less than that!