tiling over old tile adhesive?

[AliGage]

Seriously, the term "PVA" should be added to the censored words list. Anyone found swearing on the forum again should be banned!! lol

The only people that should ever use "PVA" are primary school children and blue peter presenters. Neither of which i would trust with tiling!

 

[Mike Mike]

Seriously, the term "PVA" should be added to the censored words list. Anyone found swearing on the forum again should be banned!! lol

The only people that should ever use "PVA" are primary school children and blue peter presenters. Neither of which i would trust with tiling!

Here's a story you are all going to like. An old neighbour of mine when I lived in London was site manager for a development out in Essex, 5 luxury 7 bedroom houses, with very high price tags. I tiled the downstairs floors in 600 x 600 travertine but they wanted the bathrooms and en-suites (of which there were a LOT) to be tiled on 9mm ply on the floor, unprimed on the underside or edges, and straight onto plasterboard on the walls that had been PVA'd. I refused to do it, citing 15mm ply, primed on the underside and edges, and both the floors and walls needed to be tanked (they weren't wet rooms, but even so, tank the bleeding things for the sake of a hundred quid per bathroom in a £700k house, and don't put PVA anywhere near those walls!).

We fell out over it actually, didn't speak for months afterwards, and he got someone else in who had no qualms about fixing 406 x 406 travertine those substrates. That was 8 years ago. I wonder exactly when they fell off the walls and the floor started tenting??? :lol:

 

[Tony73]

Here's a story you are all going to like. An old neighbour of mine when I lived in London was site manager for a development out in Essex, 5 luxury 7 bedroom houses, with very high price tags. I tiled the downstairs floors in 600 x 600 travertine but they wanted the bathrooms and en-suites (of which there were a LOT) to be tiled on 9mm ply on the floor, unprimed on the underside or edges, and straight onto plasterboard on the walls that had been PVA'd. I refused to do it, citing 15mm ply, primed on the underside and edges, and both the floors and walls needed to be tanked (they weren't wet rooms, but even so, tank the bleeding things for the sake of a hundred quid per bathroom in a £700k house, and don't put PVA anywhere near those walls!).

We fell out over it actually, didn't speak for months afterwards, and he got someone else in who had no qualms about fixing 406 x 406 travertine those substrates. That was 8 years ago. I wonder exactly when they fell off the walls and the floor started tenting??? :lol:

wall possibly will be ok, but 9mm ply on floor -wrong, should be at least 12mm, and ditra matt

 

[peteablard]

wall possibly will be ok, but 9mm ply on floor -wrong, should be at least 12mm, and ditra matt

Floor should be 15mm (BS minimum)

 

[Martino]

I have a few questions about this post...Whats wrong with using pva? and whats wrong with 9mm ply if its screwed every 100mm?

always looking to gain knowledge you see :-D

 

[Olz]

PVA just dries into a thin skin, and its ok at sticking pasta to coloured sheets of paper but that's about it. Think about when you get it on your hands, to get it off you just let it dry and easily peel it off.

Do you really want something so easy to peel off your hand to be the only thing holding adhesive, and therefore the tiles to the wall?




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[Martino]

But then why do plasterers use it on a ceiling?...its the same principle? it dries thin and its the only thing holding the plaster up?

 

[White Room]

Plaster weighs about 2 kg m2...

 

[steve6710]

p.v.a. is used for plastering as it theoretically should never get wet again to the degree tiles in a bathroom or kitchen may. if you paint pva onto pretty much any surface and let it dry for a day, a week, a month or a year it will seem fine untill you wet it. it then turns back to the sticky liquid you started with. plasterers like myself use pva which is the accepted practice but what happens when you have a rising damp problem or a roof or window leak?..... your plaster loses it bond 9 out of 10 .
as another example i am a fisherman who uses pva bags to fill with bait which i attach to the hook, when in the water the pva dissolves and only the bait is left for the fish.
a couple of tests you can do to see the values of pva are: pva a hard surface 6 square inch let it dry - you can sand wood with it
😛va a hard surface - leave it a day to dry - wet it and touch it- sticky again!slip slide!
sbr is for tiling primer or external plasterwork(render) as it is a latex skin which can handle getting wet again - pva aint bad in the right application if it was for tony hart and morph or blue blue peter it wouldnt be sold at builders merchants i would guess!

 

[steve6710]

sorry to add to previous thread, apply basic sand to the wet pva and allow to dry to make sand paper for the first test i mentioned