lifting tiles - Why?

[trevean]

Morning,
Can someone tell by looking at these images why the tiles have loosened. Laid on floorboards with 12mm Hardie screwed down on a bed of cement based adhesive. I'm confident floor itself is sound. Tiles are 300 x 500mm ceramic wall/floor and laid using slow set adhesive. It seemed to take ages for adhesive to go off - well over 24 hrs. Remaining tiles seem ok no hollow sound. But I think they would be easy to lift.

 

[Andy Allen]

What adhesive did you use ??

 

[trevean]

I'm reluctant to name yet but I do wonder about the adhesive but equally want to know if I have not laid these correctly.

 

[trevean]

slow set flexible.

 

[Martyn Leeds]

Adhesive skinned-over, and not back-buttered
?

 

[Andy Allen]

Adhesive mixed incorrectly, not enough water, no back buttering, adhesive not flexible enough, to much bounce on the floor due to incorrect prep...

Fact is tiling onto a wooden substrate is a minefield, unless you get everything spot on chances are it will fail.

Unless you give us the full information we can't say for sure what your issues are but I suspect there could be more that one. !

 

[Flintstone]

Adhesive not wet enough and or left to skin over.

 

[One Day]

No back-skimming to fill those waffles either.
Possible dusty backsides on the tiles?

I'd guess - too stiff a mix, possibly skinned over before no real effort to achieve a solid bed. Those tiles should be back skimmed and given a twist/push/pull.

 

[Chalker]

Cheap,adhesive with very little polymer.

 

[Ajax123]

Readybrek used instead of adhesive?

 

[trevean]

Thanks your comments.
It seems to me that the tiles did have reasonable contact with adhesive. But the adhesive doesn't have enough "glue" or "stick". I'm interested in comment about cheap adhesive, what do you mean very little polymer. The adhesive was Topps own brand.
The failure seems to me similar to what would happen if surface too absorbent - not primed. The adhesive is well stuck to the primed Hardieboard.
I wonder if the highly absorbent nature of the ceramic back has a detrimental effect on adhesive.
The mix felt ok to me it was easy to spread but perhaps with ceramic it needs to be wetter to allow it to spread more under tile ? I wasn't trying to achieve 100% bedding though.
I used a 10mm trowel. Should I have larger notch giving larger rib ?
I can't see how twisting works when laying a tile. you'd have to lay tile away from next tile then push into position risking messy joints. my method tends to be laying tile butting up to next tile and then pulling back to open joint space with a jerking motion. If the mix is right surely that should be enough. There shouldn't be a need to butter.

 

[Italy]

the adhesive on the floor,
shows white signs like the back of the tile.
that white powder was washed before laying.
and add the buttering, because the tiles
they seem curved.
and using superior adhesives does not hurt.
I know the problem, I washed 110 square meters of tiles.

 

[Andy Allen]

I only use high quality adhesive on wooden substrate......something like bal single part fast flex, grouted using an additive, back skimming the tile is a Must.

 

[WetSaw]

Ceramic tile with no back buttering probably sucked all of the moisture out of the adhesive and/or dusty back of tile.
Back buttering not only fills the indentations on the back of the tile it also keys the adhesive to it.

 

[One Day]

"twist/push/pull" just means a general agitation to encourage the ribs to collapse.
It's far better to make a bit of mess which you can clean up as you go, than to face a situation like this.
So what we know:
Ceramic onto primed hb - so the ceramic biscuit sucks all the moisture out before any bond can really happen. Solved by back-skimming the tiles before fixing.
Possibly dusty tiles - Solved by wiping or at least back-skimming.
Ribs of adhesive still show - solved by bedding in properly / wetter mix.
Poor quality adhesive from Topps. (my opinion from experience)

You did the right thing though asking. We've all had failures and we're always learning from ours and each others.