Porcelain tiles cracked

[Cheryl]

Hi there,
I really hope someone can help. I had new porcelain tiles fitted over electric underfloor heating a few months ago and, wherever a tile has been cut (like a corner), they now have a hairline crack. These tiles are over Vysal underfloor heating. Is the problem with the heating or the tile, or something else?
Many thanks for any help.
Cheryl

 

[Stewart]

Does the floor have room for expansion around the perimeter. Sounds like the tiles have been grouted to the wall or cut tight to it. A couple of pics would be handy and some more info on how the floor was tiled would be helpful in our diagnosis.....

 

[Cheryl]

Hi
Thanks for your quick reply.
The tiles had a gap of about 1/2 inch before the wall (we placed skirting on top) so I don't think its expansion. Half of the floor was suspended (so it had ply before tiling) and the rest was concrete but it has happened on both.
Cheryl

 

[Stewart]

How thick was the ply, did tiler slc over heat mat before tiling,is there an expansion joint between the ply floor and the concrete.....?

 

[nybor62]

pics please would help

 

[DHTiling]

Hi Cheryl and welcome....

Can you please upload some pics, so we can see what you can.., also if possible can you remove one of the cracked tiles so we can see what has happened underneath.?

 

[Cheryl]

Hi
If slc means levelling compound, this was only done in certain areas, not overall. Re the expansion between the ply and concrete, there is not currently a problem where these meet at all.

 

[Cheryl]

Hi
At the moment, the crack is so hairline, its not easy to see but I kow it will look worse in time.

 

[Cheryl]

Ok will try to take photo but the line is very thin, its just happened.
will come back to you.

 

[Spud]

cheryl did you get the carpenter to leave a 2mm joint when the skirtings were placed ontop of the tiles? this is very important as skirting that are butted down on to the tiles can add to the stress the floor is under when its heated also how do you use your under tile heating do you leave it at one temperature or often change the temperature settings ?

 

[Cheryl]

Hi
I've tried taking a photo but because its just happened and the hairline crack is still so clean, its impossible to see on the photo. If it was the skirting causing the problem, I would have thought it would have happened in other places but it has only happened where the tile has been cut to fit a protruding corner (6 places so far), the crack is a straight line from the V of the corner, - hope I've explained it ok. I can't take up a tile because none are loose.
Re the underfloor heating - it is thermostatically controlled but I would not have thought it gets hot enough to crack a tile, especially a porcelain one - its only warm underfoot not hot. These tiles have been laid since July and it has only started to happen. Also, we waited much longer than the recommended 2 weeks after the tiles were laid before the heating as even tested.

 

[Ian]

Hi Cheryl, so all the cracked tiles would be around door frames etc, is that right?

 

[Cheryl]

Hi
My kitchen is not a regular shape and the tiled floor flows into the conservatory so there are a few corners to go around and it has only happend at these corners, nothing at the door frames (yet).

 

[DHTiling]

IMO Cheryl, it is stress related.... L-shape cuts are the weak point hence cracking at this section.... if it is on the corners where the floor flows into conservatory, then an expansion/stress relief joint should have been installed at this point..

How long is the longest run of tiles ..?

 

[Stewart]

It does sound like they don't have any expansion on their perimeter. L cuts are generally more prone to cracking if they don't have enough expansion around what they've been cut around! also how do the tiles sound when you tap them with your knuckle.... do they sound hollow at all?