Adhesive bulging problem - Tile Advice

[Bruce Watt]

Hello All,
I hope there is someone here that can advise on a tiling problem I have.
I have had two shower trays professionally tiled with 250 * 400 mm tiles. The trays are 800 * 1200 mm and the walls are 2400mm high. The walls are tiled tray to the ceiling, so full height. One shower has three sides tiled and the other has two sides tiled. Just the area of the showers trays has been tiled. Both showers have never been used. The showers where successfully tiled and I was happy with the job.
Problem;
Slowly after a period of say 4 to 5 weeks, the tiles have bulged out from the wall. For example, over one shower wall 1200mm wide by 2400 mm high the bulge is 11mm. As you can imagine the tiles have cracked.
The adhesive company have stated that within the internal tiled angles where the tiles abut each other, this joint should have been filled with silicon and not solid grouted with silicon over the top. The other edges are free to expand, so I fail to see this as a valid reason. They also refer to a contaminate to the acrylic tiling solution that was applied to the plastered wall, ( plaster was dry, moisture resistant PB used, The substrate if all fine) The only contaminate may have been the miss emulsion coat that was applied to the plaster some months before tiling. So my question, can this miss emulsion coat really adversely affect the tiling solution and thus the adhesive to cause such a problem? The adhesive is stuck to the tiles and has detached from the wall but not across the whole surface, the edges are fine. The tiles across the top of the bath are done with the same method and are without any problem. My tiler has never seen such a defect and we are at a loss as to what the actual problem is.
If the adhesive is effected so adversely by such a minor miss coat, Is it not fit for purpose? The pressure to cause this bulge is substantial and I don't believe any adhesive would hold back such forces. The adhesive is like a sheet of timber that has become wet on one side and has bowed out. The wall is totally dry.
Please advise,
Many thanks

 

[Old Mod]

The mist coat has contaminated your substrate as adhesive company stated.
A mist coat is unacceptable as a primer.
Once wet from the adhesive, if it’s a thick enough layer, it will become ‘live’ again, and debond from the wall, this will cause the tiles to ‘tent’ away from the wall.
The fact that the corners are grouted exasperates the problem. With no where else to go, the only way is outward.
Tiling to paint is unexceptable, and is not best practice.
I might also be questioning the experience of your tiler.

 

[WetSaw]

Am I correct in saying that the substrate is plasterboard, skimmed, mist coated then acrylic primer?

 

[Waluigi]

Don’t question the adhesive manufacturer, question the Tiler that made a series of errors in his tiling preparation.

 

[Spare Tool]

What's behind the plasterboard ?

 

[CJ]

The miss coat has contaminated your substrate as adhesive company stated.
A miss coat is unacceptable as a primer.
Once wet from the adhesive, if it’s a thick enough layer, it will become ‘live’ again, and debond from the wall, this will cause the tiles to ‘tent’ away from the wall.
The fact that the corners are grouted exasperates the problem. With no where else to go, the only way is outward.
Tiling to paint is unexceptable, and is not best practice.
I might also be questioning the experience of your tiler.

He never missed the coating......but he tiled the mist coat

 

[One Day]

The adhesive hasn't "bulged". As Marc said already - the tiles have simply de-bonded from the substrate.
The adhesive has only stuck to the water-based emulsion.
The fault almost certainly lies with the (not) professional tiler who decided to fix onto emulsion.
Any movement you have experienced in the substrate will only have exacerbated the debonding process.
Solution? Take it all off, remove the contaminates, prime properly with suitable primer, and tile properly - ideally with a cement based adhesive.
(also, consider tanking because M/R plasterboard is not a suitable background for a wet area)

 

[Bruce Watt]

Am I correct in saying that the substrate is plasterboard, skimmed, mist coated then acrylic primer?

yes that is correct

 

[Bruce Watt]

What's behind the plasterboard ?

the plasterboard is on dot and dabs. The plasterboard is fine and has not moved

 

[Bruce Watt]

Thank you for your help. I am getting the impression the problem is the tiler.

The adhesive has definitely bulged. The bulge has bent the tiles to a point they have cracked.

Thank you again

 

[Time's Ran Out]

The tiles are about to fall off!
Mist coat of emulsion 100% the problem and water may have now got in behind tiles.
All to come off!

 

[One Day]

I've been tiling a long time, attended to many failures and I've never seen adhesive bulge.
I've seen tenting, where expansion pops tiles off and can look like bulging.
I would wager this is what you have here.

 

[jobdone]

Excessive bed depth can cause the tile to bulge and crack on ceramic tiles when it cures and delaminates from the paint.

 

[Perfect Tiling]

As above....paint behind this size of tile in a shower is a no no. Destined to fail from the start.....they need to come off before they fall off and damage the tray. If there is still paint on the plasterboard it needs to come off or the plasterboard be replaced then tanked to the tray before tiling. Don't tank over any paint or you could still have problems down the line. You'll probably need a different tiler.....if this one did this then he wont have a clue about tanking....

 

[Bruce Watt]

Just a quick follow up on this.

The tiles have stick to the adhesive, the adhesive has bulged causing delamination from the wall.

Bulging adhesive.
Jobdone said "Excessive bed depth can cause the tile to bulge and crack on ceramic tiles when it cures and delaminates from the paint." I think this is possibly correct.

Form the photos you can see how much the tiles and adhesive have bulged.

I wanted to record this here should anyone else have the same problem.

Thank you for all your replies.