tiling onto uneven wall

[Fred]

Hi,

I have been asked to tile my brother-in-law's downstairs toilet (I've never understood why they are called "cloakrooms" when they are not used to store coats).

It is wallpapered at the moment. He would like it tiled to dado-rail height and keep it wallpapered above this level. The one wall looks pretty awful. The plaster has blown near the bottom of the wall, which is one reason that he wants work done on the room.

When I tiled my own bathroom, one wall was not even and I had naively hoped that I could use the adhesive to level out the imperfections in the wall. I am not happy with the results to this day. I would like to redo that one wall, when I get round to it.

I've learnt my lesson and I think the best thing to do would be to make good the toilet wall before tiling. I think I could do any of the following:

1. skim the wall with plaster
2. fit plasterboard to the wall.
3. fit plywood to the wall.

I know 9mm is not much but with this being a small toilet, I'm not sure I would want to put plasterboard on the walls and make the room any smaller. OTOH perhaps I am being silly to worry about 18mm?

I think he was hoping I would tile the bottom half of the wall without disturbing the top half. The problem with this is that it stops me using the plasterboard approach as this would make the bottom half protrude more (9mm+tile width) than the top half IYSWIM.

Perhaps I could use something thinner to line the walls. I could skim with plaster or I see the Wickes web site sells 3mm plywood. I've never seen that before. I wonder if that would be any good? Would a grab adhesive be sufficient to hold it or would you use (stainless) screws?

Or should I tell him I need to do the job properly, line the whole wall and redecorate the top half at the same time. It's more work but a better result and what I would be tempted to do in my own home.

Any other advice about tiling over uneven walls?

TIA

[NT]

So all you need to do is flll the blown bits? And scrape it flat with a 2x1.

I don't see any reason to pb it, and I certainly wouldnt tile onto 3mm ply. Any tiling substrate must be rock hard.

NT

[The Natural Philosopher]

I tend to agree. I would get some bits of wood as long as the wall and simply reskim it using the wood as a guide and or scraper. You don't need a brilliant finish - just an even one - for tiling over

[stuart noble]

Ready mix tile adhesive makes a good skim. I used it when I had a huge tub left over from a previous job. Nice and light, and feathers down to a fine edge. Dries quickly. Not too different to the ready mix patching plaster type products from Wickes etc

[Rob]

Indeed - and key in to brick if the plaster's blown.

Rob

[Fred]

Thanks. I think the blown plaster is only part of the problem; I think the wall is pretty uneven where the plaster is sound too.

I have never seen 3mm ply in real life, only on their web site last night. I agree it must be very flexible but OTOH once fixed to the wall, wouldn't it be as rigid as the wall?

That is only an academic question because I will take your advice and reskim.

Thanks.

[Fred]

Thanks, that's what I will do. I'll use some wood as a derby (darby?) and reskim. I'm not sure whether to use real plaster, patching plaster, or tiling adhesive. I'll see what I've got in the garage already ;)

[Fred]

Perhaps the trick is to do this in two stages: skim with adhesive and let it dry and then apply a second coat of adhesive for the tiles? I got into trouble when I tried to do it all in one step. I think using tile adhesive is probably more expensive than using plaster but if you have some left over from another job, then that's different. Thanks.

[Phil L]

Yes, 18mm won't make any difference

But it wouldn't be noticable if you are adding a dado rail

Tile straight onto plasterboard - it's flat and tilers prefer it to a plastered wall. Simply stick the PB on the wall with adhesive and tile over, sit a dado rail on top of the edge of PB and tile up to it. It's only the one wall that needs PB, the rest can just be tiled over what's there, but I'd still put a wooden rail around the lot.

[The Natural Philosopher]

Blimey. You obviously have never built any models or repaired any caravans..

[The Natural Philosopher]

I have used anything and everything.

As long as it keys together. Bits of wood car body filler sand and cement old tile adhesive..use anything to hand.

[NT]

12mm ply is rather flexible to tile onto. Some people do it, but its always a risk of it coming adrift. 3mm might be rigid, but unless its fixed every single square millimeter I wouldnt tile onto it. The ideal tiling substrate is solid masonry.

NT

[Fred]

Right on both counts ;)

[Fred]

I never knew that. I always found 12mm ply wood to be quite rigid, whereas 9mm and 6mm are quite flexible. I'm not planning to use it but if plywood was needed, would you recommend 18mm? TIA

[stuart noble]

Absolutely. If the air can get to it, it dries faster than plaster and can be used in thick layers without sagging. Trying to pack tiles out as you go is a different matter

[Fred]

I have been and had a look and although the wall is lumpy, it is not as bad as I had thought. I may be able to skim the low bits and sand the high bits to get a smooth surface.

If it were my house where the time and money was my own, I might still chisel it all off and use plasterboard. I think that because they do not want the hassle of re papering the top half of the wall, it is making things a bit more complicated for me.

By the way, what do you prefer to fix the PB to the wall: foam or a no-more-nails type of grab adhesive?

One last question: I will be tiling the floor as well. That currently has those brittle plastic tiles on it. I removed some of these from my last house and they were held on with some sort of bitumen glue. Would you suggest I remove all the tiles and scrape off any glue and tile direct to the concrete floor, or would you tile over the tiles? I always thought tiling over tiles was cheating but I have read web sites (albeit about wall tiles) talking about doing exactly this.

TIA

[Tim Watts]

If it is bitumen, you need at least 50% completely removed. Any adhesive, other than bitumen applied on top will shear off after a few temperature cycles.

One method I used was a scutch combe chisel in an SDS to groove the screed - if you have grooves cut right through the bitumen exposing dry clean screed, that's generally enough for tile adhesive to get a decent bond and as the grooves are close, the tile gets good overally support. A good soaking in diluted SBR helps too a day prior to tiling.

If it were rubber tile adhesive, get off what you can, but tile cement seems to bond to that reasonably well - if it is tacky, blind it with a little powdered tile adhesive.