tiling onto plasterboard

Hi,
You may remember I was asking about swapping an electric shower recently. Well the plumbing and electrics all were ok thanks to the help I had from you here.
But: the tiles were tiled onto plasterboard and a tile was missing and a couple more were cracked. I guess that water has got in through these and the plasterboard has turned to mush.
I will rip it all out but I am unsure what to replace it with. OTOH I worry that if I use plasterboard again, the same thing will happen but OTOH the damaged PB has probably been there for thirty years so it lasted quite long. If it lasts that long again, everyone will be happy.
Wickes haven't got any aquapanel in stock locally and it is very expensive, so I can't use that. I did wonder about 12mm WBP. but would plasterboard work?
I have typed "tiling onto plasterboard" into google and found 101 forums where some people say you can tile onto plasterboard and an equal number of people saying you can't.
Then half the people say use PVA and half the people say don't!
So what should I use as a primer? PVA? Emulsion paint? Branded product?
Help! It's giving me a headache.
TIA
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wrote:

Hello again,
I have just found aquapanel on the B&Q web site and actually I don't think it will be much dearer than WBP. I'm guessing I would need to prime the plywood whereas I can tile direct to aquapanel, so I am considering aquapanel now. Any hints or tips for working with it? How do I cut it? What do I seal the join with, etc?
TIA
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On 23/12/10 20:39, Fred wrote:

Don't think so - I tiled some WPB with flexible Mapei tub premixed and it tool fine - the surface has plenty of roughness to key the adhesive.
The only thing with the Mapei I used (I forget the name, brown lidded tub) is it had bugger all "grab" compared to the BAL Greenstar I used on the walls. This was Ok as I wass tiling on a bench to fit the panel to the wall post tiling (it is designed as a semi-removable panel should the bog piping need replacing). You'd need to use tile spacers on the vertical. So if you go this route, you'd do well to investigate a better adhesive (start another thread maybe). A high grab adhesive makes life so much easier as you pop the tile on and it stays put - but still gives to 10-20 minutes adjustment time for tweaking.

Can't help there, but someone else will no doubt :)
--
Tim Watts

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Fred wrote:

Oh yes, it'll do that.

It wasn't damaged for thirty years, it may have only been damaged for one or two, meaning you may only get 18 months out of a new one...

Ideally, you want aquapanel, but don't forget, you don't need it everywhere - just where the worst of the water hits the wall, so if it's over a bath, you'd want the bottom 4ft, from the edge of the bath upwards to be done in aquapanel, the rest can be done in normal PB.
Extra care should be taken when grouting - the slightest gap and water will get through and make a pig's ear of everything, you might want to consider using epoxy grout - very expensive and you can only do a small amount at a time, but I've recently seen some that's been on for 3 years and it looks like it was done yesterday
--
Phil L
RSRL Tipster Of The Year 2008
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On Thu, 23 Dec 2010 21:16:14 -0000, "Phil L"

Thanks everyone for all your replies and Merry Christmas to you all.
It sounds like either WBP or aquapanel is the stuff to use here.
All the trade places had closed for the holiday, which only left the sheds. I decided to buy the aquapanel because it was less bulky to carry and transport than an 8x4 sheet of ply.
Curiously, the Wickes web site said aquapanel was 14 but the B&Q web site said it was 7. The next day I went to B&Q and it was 14. I got home and looked at the web site again and it said 14, so either I went the day after a promotion had ended or I was hallucinating!
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On 23/12/10 19:39, Fred wrote:

There are many waterproof board systems for such occasions.
Marmox is light, tiles nice, and will allow the tiles to warm up fast from any water hitting them. It is not as rigid as PB so regular close spaced supports would be a good idea - as would using a flexible grade tile adhesive and grout, which doesn't make life any harder.
There's stuff like Aquapanel and loads of others which I believe are more substantial.

WBP Ply would also also work - remember many tiled bath panels might well be of that construction. It would be a *lot* less prone to failure if water did get to it but would also be able to breath the moisture out the back over time.

Short is - yes you can - but if you get a leak it will fail badly.
The answer, if you must use PB, is to go to town trying to achieve as close to 100% adhesive bed, pull the trowel left-right (to avoid vertical channels in the adhesive) and to leave a decent grout line (at least 2mm) and pack it well to full depth, with a good quality power mix-yourself grout (again, not hard - SS bowl and wooden spoon did me as you only want to work with a few kg at a time) - no half arsed ready mixed stuff or worse, combined adhesive/grout.
Done well, it can last - I've been in flats where it's held up >10 years, but equally my last rented house they forgot to use tile spaces, the grout lines were hair thickness in places and it fell out and the PB bowed and had to be ripped out.

--
Tim Watts

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Cement & fibreglass board is ok with water indefinitely, so is a good choice. PB will just disintegrate when it gets wet, which will happen at some point. PB is more for where you dont care what happens down the line.
NT
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Tabby wrote:

No it wont if you have done the job properly
PB is more for where you dont care what happens down

PB is for people who can tile properly.

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wrote:

If you go to the British Gypsom website they recommend tiling directly onto unskimmed plaster board for greater tile adhesion. BTW Aquapanel is not waterproof it just does not disintergrate like PB when it gets wet. I would suggest putting a polythene vapour barrier behind it otherwise if water gets into the framing and rot sets in you will have a major problem. Of course a good tile job as already mentioned should do the job.
Richard
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Certainly looked that way to me when I left a piece standing in water for a couple of days.
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On 24/12/2010 15:21, stuart noble wrote:

Define 'waterproof' in this context though. No it won't deteriorate AFAIK when it gets wet, but it can't be expected to act as an barrier to prevent underlying ceilings, joists etc getting trashed in the event water gets past the tiles.
David
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Lobster wrote:

I think the point being that any water that does get past the tiles, is bad news.
I've got a problem where I tiled onto wood. its now so swollen its cracked the tiles off.
Have to redo that whole section.
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snip
There are many things you can do that dont last well. Its upto the OP if he wants to go that way or not, personally I wont recommend it.
NT
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We were somewhere around Barstow, on the edge of the desert, when the
something like:

50/50 imv. I've seen plenty of tiled p/b walls that have lasted the distance, but they've been put up by somebody who had a clue. I've also seen plenty with problems. Fwiw, I tend to use wpb where possible.
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On 25/12/2010 13:30, Grimly Curmudgeon wrote:

Certainly in bathrooms, a lot depends on whether you tile up to the ceiling. If not, you have an edge which is vulnerable.
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On Fri, 24 Dec 2010 06:55:43 -0800 (PST), Tricky Dicky

I haven't read the web site but I wonder whether they meant to tile directly to PB in non-wet areas? I imagine tiling onto PB in a downstairs toilet, possibly even a kitchen, would be ok? Whereas I am looking for something to use in a shower cubicle where PB would not last long.
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Fred wrote:

It lasts. Don't worry.
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wrote:

If you're thorough enough it might, if youre lucky. But its a lousy gamble.
NT
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Fred wrote:

Its perfectly OK to tile onto bare plasterboard IF it rigid enough so that the things wont crack off and the tiling is done properly so water cannot collect anywhere in contact with the board.
Any collection of water will in time rot a wooden structure, so I prefer to be warned of problems by the mushy plasterboard BEFORE the wood rots.
Lot easier to fix.
If the plasterboard is ill supported and flexible, use MDF or even chip. It tiles really well.
DO pay great attention to sealing corners and edges. I seal BEFORE I tile. so that the tiles cover the sealer.
No tiles wont stick to silicone, but they don't have to. Its only a small area in the corner.
As to PVA well no, I don't like to seal The adhesives I use take forever to dry on a non porous substrate.
Finally, I regard a tile wall as that - a wall made of tiles, what lies behind is only to support them. The tiles ARE the important part and should be well laid and conscientiously grouted to keep the water on the right side. The decorative aspect is in this context secondary.
Other people take the view that the tiles will be badly laid, not prevent water ingress, and are merely a decorative layer, so what lies behind should be water proof.

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wrote:

Making a layer of tiles stay truly waterproof for decades is a challenge. Doable, yes, but in practice it tends not to go that way.
NT
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