disagreeing with local tiler

[jactac]

I recently asked for and received some very good advice from this forum.
Basicaly I was going to retile our bathroom wall and floor. I removed all the old wall tiles and plasterboard walls and also removed old floor tiles from the chipboard floor, then replaced brandnew plasterboards all round. The walls and floor are both completely sound and level.
The advice I sought was how to prepare the chipboard floor and new plasterboards for retiling, the advice was NOT to use Unibond PVA.
Now after some thought I have realised I really dont have the the time to do the tiling myself, therefore I have asked a local tiler (recomended by "friend") to do the tiling, however after giving me a price and start date he has concerned me by saying he WILL use Unibond PVA on the plasterboards AND floor before retiling, "cos you need it to stick see mate" !!

I pointed out my concerns about using Unibond and all I had was the "I've been tiling for 20 years" story "without any problems".
So basicaly I've put the job on hold until I find another tiler or will it be ok to use what he suggests .
This guys tiling looks great but I just dont want tiles coming loose in months to come.

What should I do, as Unibond seems to be the first thing that comes out of peoples mouths around here, even the fella selling the tiles said "Unibond it mate" .

Anymore advice on this subject would be very appreciated.
Thanks.

[wine~o]

"cos you need it to stick mate"

Lovely quote, I wonder why "Tile Adhesive" Is called tile adhesive ??

Nope, just pva it first....it'll be fiiiiine....

[haveagohero]

If his work looks good then just supply him some SBR to use instead and just tell him it is for your peace of mind and not to cause any offence. Or ask him what the adhesive manufacturer reccomends

[jactac]

SBR ?
Whats this ?

[wine~o]

SBR ?
Whats this ?

One example (Never used the site so not a recommendation)

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EDIT...It would seem this particular site have been banned for some reason....try Googling "SBR" or "Bonding adhesive"

[jactac]

Isnt SBR just like Unibond PVA ?
There are so many bonding agents on the market,which one can I just use on chipboard before tiling.
This floor is only 2 square mts, is solid, even and has no movement whatsoever..

[Pooneil]

When did this obsession with slapping PVA on everything begin.

PVA will form a film on the surface of the substrate, once it gets damp again it can peel. It can make skin between board and adhesive.

Of course it may not turn out to be a problem, but there is a reason many adhesive brands actually specify NOT to use PVA. Is your tiler prepared to cover the adhesive guarantee that will be void if he puts PVA on?

I expect it just something he's always done rather than because he's a cowboy... old habits die hard.

[BRUNO]

I had a customer yesterday telling me I should cover the bricks in PVA near his down pipe that was leaking, to seal out the water...told me its what his brother the builder did..

[haveagohero]

SBR is not sensitive to moisture like pva but will kill suction etc. personall i never buy the adhesive manufacturer primers as i don't believe there are any benefits over using SBR which is available from any builders merchant. If you want a really good bond between adhesive and substrate prime a small portion of the floor and wait for it to go tacky then spread your adhesive and lay your tiles, carry on like this untill your finished

[village idiot]

what mudster has to say

[BRUNO]

Interesting that he says use the SBR on the floor if it's dusty, but not on walls

[haveagohero]

There is no reason that i know of that SBR can't be used on walls, but if anyone can sugest a reason and an alternative i am happy to listen. I also don't use SBR as a slurry coat on a floor i just sweep then hoover the floor and mix SBR with water and put this on with a roller (normally 2 coats going in opposite directions)

[DuffMan]

Are the walls skimmed or just plasterboard?

[Leif]

Isnt SBR just like Unibond PVA ?
There are so many bonding agents on the market,which one can I just use on chipboard before tiling.
This floor is only 2 square mts, is solid, even and has no movement whatsoever..

If you apply adhesive directly to a porous surface, moisture is sucked out so quickly that it dries before it can soak into the surface. The result is a weak bond. Exactly the same happens with paint, try it and you will see that the paint peels off easy peasy. Also, if you tile with a cement based adhesive directly on plaster you get something called Ettringite failure. Basically the tiles fall off.

PVA does seal the surface but it is water soluble and if water gets through the adhesive, it can soften the PVA, and the tiles fall off. Adhesives are not always water proof. PVA also stops the adhesive forming a strong bond with the surface. Primer such as SBR seals the surface, is not water soluble and provides a good key for the adhesive.

Tilers used PVA for a long time. So I guess it does work, sort of, but primer is much better.