tiling on to plaster board

[what..the?]

i was told it would be a marine ply surface to tile, so bought adhesive for ply and stone applications just in case, then i asked if they could use wedi board which is better in damp conditions, but I have found they have just fitted plaster board instead and this is a wall where a shower will be.

- can they tile safely onto plaster board, the tiles are 300x300 glazed porcelain floor to ceiling
- should they seal the plaster board first? They said they would pva but I hear you should really used balbond or tilers adhesive if the pva sticks it really sticks and you wreak all the walls removing them in the future. But chances are the water content in the adhesive can sometimes reactivate the pva making them fall off, PVA also it leaves a thin layer on top of the surface which doesn't help the bond
- i also hear that tanking is recommended if a shower is involved because even with water res grout and adhesive, with even a pin prick hole if water got behind it would wreak the plaster board and the bond of the tiles.

Thanks in advance

[SlackAlice]

Used plasterboard in my shower room, gave it two coats pva (diluted 4 parts water). Gave it minimum 24hrs to dry. Used quality waterproof tile adhesive (unibond, I think). Then used waterproof tile grout (unibond again) with a scrim and a finger lol. Ensured grout was well firmed (?) using an old blunt pencil.

Shower tray was fitted first so that tiles overlapped edge. Pure silicone sealant in between tile edge and shower tray. Topped of with a more decorative sealant to make it look good.

This was done about 10 years ago and no problems so far, other than the OH saying she's fed up with the tiles. Oh, and it's a power shower often used full blast.

[what..the?]

but my builders are tiling as part of the job so the finish won't be as good as you, they will be slap dash so i worry about water ingress

[SlackAlice]

Slap dash builders? Oh dear, says it all.

My rates are cheap lol

[The Builder]

Years ago, it was quite normal to just tile over plasterboard. We've all learnt since then. With respect to Alice, and anyone else who has this arrangement, you've either been very lucky, or it's all hidden from view.
I've stripped out several showers (for alterations) and found all kinds of horrors behind.......... wet rot, mould etc.

PVA helps with bonding and, to a point, sealing. Bonding is fine because plasterboard's paper surface is treated to bond with plaster (or, in this case, tile adhesive).

I know your builders can be ............... er ............ how can I put this ......... less than attentive, but, check just what kind of P/board it is.
There are loads of different types for different jobs ........ Soundcheck, Fireboard, Aquaboard. etc etc. They are often in different colours. The board I use for showers is Orange....... but it depends on the make. If they've used the right one .......... no problem Mrs What.

[SlackAlice]

^^
Follow this man's advice, it's good.
Just knew you would be on to comment!!!

[buildersmate]

I have great respect for what The Builder says (so much so that I don't often answer this section any more). But my experience is similiar with regard to putting right sins of previous owners / builders.
So I'd be insisting that they didn't use plasterboard behind here at all - but pulled out the offending section of plasterboard and installing Wedi Board (or marine ply) as the substrate. It is really, really difficult to prevent water getting down the back.
Even with Wedi board in place, I pay a hell of a lot of time in checking the gap between the Wedi board and the shower tray is completely filled with a high grade mastic to stop any chance of water getting down under the bottom of the tiles (once they are put in later) and behind/down the shower tray.

[The Builder]

Well ......... thank you Alice and BM for what you say. I'm just glad to help.

There's a very good, often overlooked point that BM made about mastic (silicone usually). People often tile, grout, and then apply the bottme edge silicone seal to finish.
That's all good, but ......... before tiling, make sure any space between tray and board is filled with sealant. In fact, I usually run another bead on top of that, so that the first tile beds into it. The finish bead is then almost a "sacrificial" one that could be damaged without the system springing a leak.
Tiling has always been associated with DIY. It's actually a very skilled and precise business. That's why I go a bit OTT. When using a "proper" tiler (had to get a plug in for Trimeresurus there) ...... they have their own preferred methods.

[what..the?]

thanks for answers, I rang the tile company this morning where I bought the tiles the guy said the same and said use 'tile backer board ' 12.5mm to match the standard plaster board thickness in the rest of the room in the non-wet areas. Is it ok to use basic plaster board in the rest of the room, I asked for it round the sink and was made to feel a t**t

[The Builder]

Mrs What ....... if you're particularly messy around the sink, throwing loads of water around, then it might be a good idea lol.
Otherwise, it's not normally subject to a continuous stream of water, so not necessary.
Absolutely no need to be made to feel a t**t though.

[what..the?]

thanks a lot mate :)