Tiling over plywood wall in bathroom.

[ag1975]

I've used plywood on a bathroom wall behind a toilet, that I'll be tiling onto. Do I need to seal it regardless of it not getting directly wet? Should I use tanking or just go with the waterproof adhesive and waterproof grout or do something else? The ply I've used 18mm thick and is external WDP, which I'm guessing is treated anyway...is that right? Can anyone help me with that? Thanks.

[white pan man]

you will need to to seal the ply,not with pva but a proper sealer,this has nothing to do with area getting wet or not,it allows permanent strong bonding of the tiles to the wood surface,if you do not seal,tiles will start to become loose within a few months

[handyman]

It will tell you what/if surface needs sealed, and what to seal it with, on the adhesive you buy.

[Maxsys]

You should not use Ply on walls to tile onto it is not a stable tile background, fine on floors not on walls.

You should have used MR plasterboard, or better still cement based tile backing board, such as aquapanel, or hardibacker board.

Do not use adhesive from the DIY sheds, use a quality trade adhesive and grout, such as Mapei, (the Mapei one sold be BNQ is not the same as the trade product) or BAL or the like. You don't say what size and type of tiles you are using? And you don't say how the PLY has been fixed to the substrate? And what is the substrate, studwork, brick, block?

As for "waterproof" adhesive and grout, the only Grout that is totally waterproof is Epoxy based, all the stuff that you see advertised as "waterproof" what it actually means is that it will not crumble or breakdown when subjected to water, it is however permeable, and therefore NOT "waterproof" in the true sense. If the tiled area is likely to get wet then any small imperfection, or pinhole in the grout will let water through and eventually the tiles will fail, if the ply gets wet consistently it will delaminate.

If it was me i would be taking it down and doing it again.

[ag1975]

Thanks for the tips :)

Maxsys - I've only used the ply behind the toilet and nowhere else, it's unlikely to get wet so I went with the ply. Also the tiles being used are 12" x 6" ceramic.
The ply has been screwed onto timber battens and is secure with no give, should this be ok?

Another couple of queries about the floor tiling. As far as I know you shouldn't put toilets on top of floor tiles and should always cut the tile around the toilet, but the guy I'm working with insists on putting the toilet on top of the tiles. Am I right? I think I've heard of tiles cracking before, when put directly under toilets.

Is it advisable to tile directly onto existing wall tiles around the shower? The tiles are firmly adhered to the wall and aren't damaged. We were thinking of just pulling them down, but the damage done to the plaster underneath may take more time than we've got.

One more thing :) We're retiling the floor, is it ok to tile over the existing tiles, bearing in mind some of the tiles are damaged in places and have come away and need 'levelling off' if you like. We can either rip the floor tiles up down to the stone floor, put a layer of ply or something over them, or use something to fill in the gaps (where the tiles have broken and come off) and tile straight on top of them. What's the best thing to do??

[Colour Republic]

Thanks for the tips :)

Maxsys - I've only used the ply behind the toilet and nowhere else, it's unlikely to get wet so I went with the ply. Also the tiles being used are 12" x 6" ceramic.
The ply has been screwed onto timber battens and is secure with no give, should this be ok?

Another couple of queries about the floor tiling. As far as I know you shouldn't put toilets on top of floor tiles and should always cut the tile around the toilet, but the guy I'm working with insists on putting the toilet on top of the tiles. Am I right? I think I've heard of tiles cracking before, when put directly under toilets.

No you should place the suite on top of the tiles not cut the tiles around. The reason you may have seen cracked tiles is because the tiles themselves were poorly installed. Maybe dot and dabbed which creates voids and weak points. Correctly installed tiles on a stable substrate will not crack.

Is it advisable to tile directly onto existing wall tiles around the shower? The tiles are firmly adhered to the wall and aren't damaged. We were thinking of just pulling them down, but the damage done to the plaster underneath may take more time than we've got.

Some people do tile over tiles but is not something I would ever advise. You may need to think about weight limits on the substrate to. Be safe, do it right and take them down.

One more thing :) We're retiling the floor, is it ok to tile over the existing tiles, bearing in mind some of the tiles are damaged in places and have come away and need 'levelling off' if you like. We can either rip the floor tiles up down to the stone floor, put a layer of ply or something over them, or use something to fill in the gaps (where the tiles have broken and come off) and tile straight on top of them. What's the best thing to do??

Again rip the floor up. what do you mean by 'Stone' floor? Do you mean a screeded / concrete floor or you think there is a natural stone floor underneath?

[ag1975]

It's actually a concrete floor. So you think I should take the old tiles up? Most of them are very secure, but there's the odd one or two that have broken and come up.

Can the tiles be laid onto concrete without sealing? It's not porous so shouldn't need sealing should it?

We're using quite large porcelain tiles by the way, about 20 x 20 "

[Maxsys]

As already stated, take up the old tiles, and then use a SLC (Self leveling Compound) over the concrete, you want a nice clean and flat surface to tile too, make sure you use a good quality trade adhesive and grout as already stated and follow the manufacturers instructions with regards to any treatment the SLC needs prior to tiling. Try and stay away from white grout or the likes on the floor, it will look crap after a couple of months.

[tictic]

seal the ply with sbr proir to fixing tiles to it..

as for the floor,what tiles are down on it?

[ag1975]

I'm not totally sure what tiles are on the floor, they seem like thin ceramic tiles that break quite easily and they're about 30 years old.

[tictic]

you sure they are not "marley" tiles??
do they snap.. as if they are old vinly tiles...

pics would help....

if they are marley tiles they will be stuck down with a bituim tpye adhesive(very sticky and black)...

if so they will have traces off asbestos in them,so any loose ones,soak down and pull up(wear ppe..mask ect....bag them and call your local council re:disposal,

rest of floor use a latex slc...F Ball one imo...

[ag1975]

The tiles do snap easily and almost look vinyl so they could be marley, I'll put pics on tomorrow.

With the slc, why latex?

Cheers.

[ag1975]

Photos as promised.



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You can see where the tiles have come away after removing the toilet and bath.

[08hamster]

Standard ext ply has tendency to de-laminate over time. By sealing it you will not prevent this - indeed you will probably reduce the key of the adhesive - I have seen tiles fall off ply before de-lamination has even started. use a proper substrate.

[tictic]

latex slc is the best form to use ...imo...up to you if you want to use the waterbased one mate ,but not for me...

as for the section around the bog....sbr across it then up and down it....

then with that size off ceramic tile,just buy yourself a tub off Bal White Star(for that section)...jobs a good yun.... :thumbright..