Cracking of cut tiles - TilersForums.com

[Dean Evans]

Evening All,

I have recently had large format tiles installed 1200mm x 2400mm x 6 mm thick. All laid to a very good standard on top of UFH however 90 percent of the cut tiles have cracked. There is no other cracking on any full tiles or grout lines that suggest it’s structural.

I have attached a photo of the corner cut on the tile which I believe is the cause of the cracking. Your professional advice would be appreciated.

 

[Flintstone]

Drilling the corner of the cut is important with these tiles to take away the tension and avoid cracks from that weak point. This looks like it has been drilled. Perhaps @3_fall can advise, he specialises in these tiles

 

[Dean Evans]

The drill cut is poor and not giving a clean sweep where it meets the straight cut lines which is what I believe is the cause of cracking. Hope this makes sense?

 

[Old Mod]

Any chance of some more images please, the room as a whole and a couple of the cracked pieces.
I’m afraid being laid to a good standard and 90% cracked is quite a contradiction in terms.
If 90% are cracked, it’s either poorly laid or the ufh has been commissioned/operated incorrectly, if you are convinced it is not structural.
Who did the floor prep?

The drill cut is poor and not giving a clean sweep where it meets the straight cut lines which is what I believe is the cause of cracking

it’s more likely that there is either a lump in the floor screed on the corner, which is commonplace, or there is too much adhesive under it on that point.

 

[Dean Evans]

Any chance of some more images please, the room as a whole and a couple of the cracked pieces.
I’m afraid being laid to a good standard and 90% cracked is quite a contradiction in terms.
If 90% are cracked, it’s either poorly laid or the ufh has been commissioned/operated incorrectly, if you are convinced it is not structural.
Who did the floor prep?



it’s more likely that there is either a lump in the floor screed on the corner, which is commonplace, or there is too much adhesive under it on that point.

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Sorry there is about 50m2 of floor tiling area. There are 7 cut tiles within that 50m2 6 of the cut tiles have cracked. The level, line and laying to the eye looks very good. The only area that looks poor is the drilling of the 7 cut tiles. I’ll send more photos when I get home later.

 

[Dumbo]

Is that grout under neath the silicone if it is thst is probably your problem . Also what about background prep what was it . Is

 

[Dean Evans]

Is that grout under neath the silicone if it is thst is probably your problem . Also what about background prep what was it . Is

Yes to the grout so no expansion joint to the external wall. Floor make up Liquid screed on top of UFH. Then the tiler installed 30mm of liquid product on top again (I’m not sure what product this was) and then laid matting before installing the tiles.

 

[Dumbo]

Why did he put 30mm on top of screed , can we take it, it is wet ufh
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Did he do a moisture test on the screed , was the ufh commissioned before tiling
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What matting did he lay

 

[Dean Evans]

Why did he put 30mm on top of screed , can we take it, it is wet ufh
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Did he do a moisture test on the screed , was the ufh commissioned before tiling
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What matting did he lay

Yes wet UFH. He gave the incorrect build up required before the liquid screed was installed so had to make it up. Yes he carried out moisture test and the UFH was commissioned. Not sure on the matting but it looked like grey rolls of thin polystyrene.

 

[Old Mod]

30mm! That’s a huge amount, were the levels incorrect?
Do you know what type of matting, what colour was it?
Do you have any left over bags of anything at all?
Were they installed using a frame?
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Sorry, seems you’ve just answered some questions.

 

[Dean Evans]

30mm! That’s a huge amount, were the levels incorrect?
Do you know what type of matting, what colour was it?
Do you have any left over bags of anything at all?
Were they installed using a frame?
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Sorry, seems you’ve just answered some questions.

Here is a photo off the manufacturer web site of how the cut tile should look when cut. A smooth clean curve which has been cut with a diamond cutter which looks about a 50mm in diameter on the photo (I am awaiting confirmation off the manufacturer) I’ve got a jagged cut that doesn’t line up with the straight cuts. I know the fitters used a 6mm still bit. Also they installed stress pads on the back of the cut tiles and painted what I believe was fibreglass on the back. This along with the grout to the external is what is causing the cut tiles to split ?
All other full tiles and grout lines are not showing any cracking or movement whatsoever. Thoughts please? (Compare the manufacturer cut photo compared to what I have had installed on my original post).

 

[Old Mod]

The idea of drilling the corner is only to form an arc, I’ve never found size of the arc to be a factor.
mots more difficult for a crack to start within an arc than it is a 90° corner.
were skirtings fitted on top?
Did you remove the silicone on the external corner?
Do you have any idea on the adhesive used?
Were the slabs ‘clipped’ down with a levelling system?
Was a lifting frame used during installation?
Has the ufh been turned back on again?
How long after installation were you told to wait, if it is?

 

[Dumbo]

Even if it was done well and I appreciate you don't like it cracked but I don't think you would of like the aesthetics of a 30 mm hole on that corner . I understand what you say about misalignment of the hole but you still have a radius on the corner .

 

[Old Mod]

I don't think you would of like the aesthetics of a 30 mm hole on that corner .

What I’ll do Jerry is undercut the bottom of the wall, so effectively the corner of the slab slides in the wall, that way the cut edges will go close to the wall.

 

[Dumbo]

What I’ll do Jerry is undercut the bottom of the wall, so effectively the corner of the slab slides in the wall, that way the cut edges will go close to the wall.

See you would do that, my method is to have a hissy fit, tell them I am an artist and can't work if it hasn't been prepped properly and then storm out