Tiling prepration query - help needed.

[ZeitGeist]

Hi,

In a moment of madness I decided to retile my bathroom. First thing is to tremove the existing tiles. However, small depressions exist where some plaster has come of with a couple of tiles. Can this be taken care of by justing adding a bit more adhesive mix to add depth?

On another wall, a lot of the skim (?) plaster has come off revealing the base layer. Can I simply tile over this without getting the base layer skimmed?

What would you recommend to cover any bare plaster of will the adhesive be ok for this as well?

BTW - bought wterproof tile adhesive from Wickes and there pricing is weird - watch out for offers at aisle ends as two of the largest tubs (10 ltr) were on offer at two for £20.

Thanks for any advice.

Regards,

Francis

[benpost]

Hi, I'm in the same situation but I'm having 2/3 of the walls re skimmed. The plasterer said neat pva with a brush over the sandy areas (where its gone all the way back to wall render), and get off loose bits then roller the rest of the walls with 50/50 mix pva and water. this includes where its back to bare plaster and also where there is old tile adhesive that is still solid.

I guess for tiling on top you would still have to do this pva layer otherwise the moisture will get sucked out of the tile adhesive and it may not hold the tiles properly. Hope that helps.

Did you get the adhesive/grout all in one stuff or is it just adhesive? I'm probably getting mine from wickes too.

[ZeitGeist]

Thanks for the tips.

I got wall waterproof adhesive only and separate waterproof grout.

Regards,

Francis

[benpost]

Hi Francis, I would wait for another reply to confirm what I said as I'm a DIY novice, but I think its probably right. I asked about the adhesive as I know they do one which is multipurpose (adhesive and grout) but not sure if its any good, maybe one of the experienced DIY'ers here can help. Ben

[The Medway Handyman]

Wickes Tile & Grout is OK, but multi purpose products don't work as well as specific ones. The grout sometimes 'pinholes' as it dries out.

[Dave Plowman (News)]

Yes - if what's below is sound. I'd give it a soak in a PVA mix first, though.

Won't do any harm to use the PVA solution eveywhere first.

I tried Wicks 'waterproof' for a recent job involving large porcelain tiles - and they fell off one by one. Got my money back. Homebase waterproof adhesive/grout (white rather than the Wicks beige) I found excellent. But it was on special offer - at full price a 'decent' brand might be just as good value.

[Dave Plowman (News)]

Even if using an adhesive said to be a grout as well, don't use it as a grout. Much easier to use a proper powder (add water) grout afterwards. Avoid ready mixed grouts too. IMHO.

[Dave Plowman (News)]

That sounds wrong to me - you want the PVA to soak into the plaster. So I'd not use it undiluted at all for this purpose.

I'd also remove all old adhesive - at least to the point where it is reasonably flat.

[ZeitGeist]

Thanks Dave. But I get confused after seeing this

there a problem or not? what is the general consensus?

Thanks.

[stuart noble]

The purpose of a pva seal is to reduce the suction of the surface, not to form a film or act as an adhesive. I dilute it with 4 parts water as a starting point. There's no hard and fast rule, you just have to judge whether it's sitting on the surface or not. Most tile adhesives are formulated to cope with porous walls, and you can tell when you spread it whether it's going to bond or not. I've never come across a plaster surface it didn't adhere to.

[benpost]

just read the replies, so although that article suggests not using pva at all, in reality with crumbly surfaces, a dilute solution can help?

i cant see how the tiles would stick to the sandy render patches i have where the plaster has come off?

also, once the pva'd area is dry, can you tell whether its left a thin layer? on the render which i pva'd neat it doesnt feel sticky. where as on some plaster surrounding it, it does.

cheers

[Dave Plowman (News)]

If you have old absorbent plaster, I'd use it. But not neat. I go for four parts water to one of PVA. If the plaster is excellent and recent - or you're going direct to plasterboard, no need.

[Andy Dee]

I too have seen the warnings regarding using PVA as a sealer under tiles. However, I have just removed the tiles from my kitchen window sill which was untreated cement render. The tiles just fell off, leaving the surface clean. The tiles had a nice layer of adhesive, then dust and were not really stuck at all.

I will use PVA.

A

[benpost]

i know what you mean, for example the crumbly sandy stuff under the old plaster is so dry and nothing would stick to it. pva must be essential for areas like that. thanks for tip on watering down, as this lets the glue soak in better. maybe applying it neat is what is not advised as it may just sit on the surface?

[Dave Plowman (News)]

It would indeed. Neat PVA is something like 'no nails'. You'd not expect that to soak in.

[The Natural Philosopher]

yes, BUT it makes it hard to get an even finish.

Use a DIY type reskim product and a long straight bit of wood as a scraper. I've even used..er ..tile cement for this ;-)

With tiles, perfect finish is not required, but perfectly flat is..ie. small pits are no problem, large undulations are.

Its fine.

[The Natural Philosopher]

Its just about useable but its less than good at either job:I now swear by evostik waterproof adhesive, and BAL: grout.

[The Natural Philosopher]

if you have crap really old [plaster, PVA will glue it all; together. So yes, thats a good idea..BUT most tile adhesives are designed to waork on 'sucky' surfaces and may take a hell of a long time to 'grab' on a PVA'ed surfec.

Id the render is sound, it will stick.

thats pure surface smoothness.