Surfaces for tiling...

Hi

I'm in the process of refitting my bathroom and am seeking some tiling advice.

Three of the walls have new unskimmed plasterboard, and the fourth wall is made of ply (it conceals pipework and a cistern for the wall hung WC).

Is it OK to tile directly onto these surfaces? If so, what preparation is recommended. Finally, could someone suggest the best tile adhesive to use?

Many thanks,

Steve

Reply to
stevelup
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Yes, but...

PVA them first.

A nice, sticky wall tile adhesive. Avoid 'adhesive and grout in one' products. Most of the sheds carry their own brand, I've used several, and they've been fine.

Reply to
Grunff

Yes.

None at all.

I have found evostik waterproof to be convenient fast grabbing and pretty easy to use.

Try and make the grout waterproof as well.. I use BAL grout and an additive..looks like PVA to me - anyway that works well.

Reply to
The Natural Philosopher

Don;t bother. Waster of time. Makes the adhesive take longer to set as well.

Reply to
The Natural Philosopher

Well, although I can't say I've tried with and without, my reason for always PVAing is to provide a dust-free surface. Both ply and PB tend to be quite dusty, especially if you've been plastering/filling in the room. A coat of PVA provides a sound, dust-free surface to tile onto.

Reply to
Grunff

Yeah but the adhesive is designed to cope with bad surfaces

Reply to
Stuart Noble

On the PB walls, just tile over them, PB is the best surface for tiling onto...WRT you plywood, if it were mine, I would screw pb to this also, although many people just tile directly onto wood, I find it can shrink/expand, ever so slightly over the years and the hardened adhesive does not, meaning that the tiles and adhesive are not bonded to the timber...the only time I have ever found tiles actually stuck to timber is when silicone has been used as adhesive, for small boxed in pieces here and there, obvously not full walls.

Any, they're virtually all the same

Reply to
Phil L

Thanks everyone for your input.

Cheers,

Steve

Reply to
stevelup

A lot depends on the adhesive..the Evostik I mentioned is slightly flexible when set..you can also get floor tile cement that is flexible to a small degree.

Unless your house is subject to wild variations in humidity, these =should be enough to cope with any slight movements.

Reply to
The Natural Philosopher

You can tile direct if you dont mind it all falling apart after 15 years, and having to redo it. If you want it to last better one thing you need is a waterproof membrane, as tiles really cant be counted on to be waterproof, and both ply and PB are vulnerable to water. The othing thing is the right adhesive. The BAL site has guides on these things.

NT

Reply to
meow2222

I was curious about this one, so I contacted the technical departments of three leading adhesives companies - BAL, Dunlop and Ardex.

One said yes and the second said no and the third said that it didn't matter. I haven't got my notes with me and can't remember who said which. Either way, I'm no further forward.

Then I discovered that they are all owned by the same company.

Reply to
Andy Hall

You can always count on Andy to do his research :-)

Lol.

Reply to
Grunff

Tiles not waterproof? And how does this membrane idea work then? How is it fixed to the wall, and how are the tiles stuck to the membrane? Easier to use aquapanel I would have thought.

Reply to
Stuart Noble

I can't believe you take any notice of what manufacturers say. It either works or it doesn't and, in this case, you can tell when you slap the first tile on. If it needs sealing, then seal it. I think perhaps you're looking for certainties in situations where the conditions of use are unknown.

Reply to
Stuart Noble

Well.... generally I find that following the manufacturer's recommendations on the use of a product is a Good Thing. It avoids embarassments like the Legendary Hacksaw Incident.

In the partcular case in point, I don't agree with you that one would find out after the first tile. It's entirely possible that it would appear to stick OK at first and then at some point down the road, adhesion would turn out to be poor and the tiles would begin to fall off. That would be something of a waste of time an materials since one would then need to remove all of the tiles, carefully clean them off, rectify the problem and stick them back.

If the problem was that the substrate had not been sealed and should have been then it is not quite so bad, but if one had sealed it and shouldn't have done, then the thought of replacing the substrate as well is not appealing at all.

In comparison, a few phone calls is hardly a large investment.

Many years ago, for the purposes of going to customers in remote places, attending trade shows as an exhibitor or whatever, someone taught me the principle of the 6Ps. In layman's terms this is Proper Preparation Prevents Piss Poor Performance.

This would appear to be a classic opportunity to apply that principle.

One manufacturer indicated that the substrate should be dusted and then wiped with a damp cloth and allowed to dry because their adhesive works better if its liquid content can soak into the surface - PVA reduced that, they said.

Another said that PVA was better because it sealed the surface, cut down the dust and prevented the liquid content of the adhesive soaking away quickly into the substrate.

Perhaps the products are different. Probably I'll use a very weak PVA solution and achieve the apparent benefits without the risks?

Reply to
Andy Hall

Non-cement-based, cures by drying out.

Cement-based, water needed as part of the cure, so stop it soaking in.

The BAL adhesive I used specified BAL primer (it would !). I may just have used PVA, but I had spare primer from the the BAL WP1 waterproofing so used it anyway. I didn't smell like PVA (had an ammonia smell) - the BAL stuff is all polyester-based I believe. Cheers, Simon.

Reply to
sm_jamieson

A tile should be difficult to pull right off a after a few minutes. Slides a little but will hang on to even an overhead surface quite happily without support. I've never known that sort of bond to get worse as it dries but, if you don't have it to start with, you might consider sealing the plaster (or using more adhesive).

Fine if anyone knows what they're talking about, but these technical staff are not ex-tilers or chemists. They're just reading from a script and telling you their name's Darren and to have a nice day.

Indeed. Prepare your surface accordingly, but someone at the other end of the phone has no idea what *you* mean by "dusty" or "porous".

But all these adhesives contain pva, or very similar resins, and the net result is likely to be the same

Different call centre I expect

Unlikely to do any harm I suppose.

Reply to
Stuart Noble

If its going to fail, it will be in the first year.

Plasterboard will die at teh first whiff of damp, and PVA won't stop it either.

Likewise a soaking wet bit of ply wont last long, PVA or not.

Or do you see boat builders covering ply hulls in PVA to waterproof them? No. I think not.

PVA is not waterpoof in any sense of the word. Its not even water resistant. It WILL stop water soaking into to stuff like screed, because it's already there instead. It WILL go white soft and scummy when it gets wet, and fall off a surface.

That's why they are used in bathrooms, swimming pools, and on house rooves of course. To let the water pass freely. That's why we make basins out of glazed china, like wot tiles are made of, to let the water soak out. Thats why toilets, also made of glazedse porcelain, leak and dribble everywhere.

Sometimes you are a pillock.

Tiles are 100% waterproof. The only think you need to worry about is grout, which is why you need to use a setting type grout that won't degraded under water, and fill its pores with your blasted PVA, so although the PVA softens when wet, it won't let water migrate through

Tiles can be couunted on to be waterproof. Your tiling apparently, cannot. That is YOUR problem however.

Of course they are vulnerable. Guess why we put TILES ON THEM?

Reply to
The Natural Philosopher

I think they definitely are.

Ive tiled 4 bathrooms and 2 kitchens and about 60 meters of slate floor in this house. More in previous ones.

The typical crap wall tile adhesives that also grout, seem to be a sort of polyfilla. They grab fast on unsealed walls, but are pretty weak, and water does seem to soak into the grout, and I am not sure it sets anyway. Just dries.

For wall tile use I now use evostik waterproof. This seems to also be a drying rather than curing glue, but its flexible, fairly fast grabbing and seems highly water resistant. Its sort of feels like no more nails actually. Then BAL grout with a little PVA in critical areas IS a setting type product. and is my choice for grout. When I have used the evostik over non porous surfaces its taken an age to dry and set - several days.

Finally I use ARDEX floor tile cement - Ive used two - a rapid set straight and a flexible slow set. I had trouble with dust and a little trouble where I didn't seal the screed properly..it sucked the wet out and the setting was weak. Ripped up the offending slate and replaced it.

So the PVA before tiling is all about dust and/or not sucking up water out of compounds that don't DRY, but SET. In my case Ardex only.

It does f*ck all to waterproof anything except a mortar mix. Tiles are

1000 times more waterproof, its only in the grout where it has any possible uses in that area.

Reply to
The Natural Philosopher

You bear out my experience exactly.

Reply to
The Natural Philosopher

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