Hollow Sounds And Space Under Edge Of Tiles?

chris1012

We are having our kitchen redone due to problems with our suspended flooring.
As a result we have put a concrete floor down.
We have just had our tiler start on the job - laying 40m2 of porcelain tiles (60*60)

We have just inspected some of the tiles that were laid and have noticed that a couple of them sound hollow in places and when we look around the edges of the tiles, you can see gaps between the base of the tile and concrete flooring.

Please see pictures attached.

Please see video of the tiler tiling - Kitchen_20170901_122447.mp4 - https://drive.google.com/open?id=0Bz6kL5nCR1XKbkg4MWFpREFValE

*We also have underfloor heating which had been left on by the builders before the tiler started the job and was only switched off between 30mins-1hr before hand. Not sure if any relevance to the above?


Is this normal or do we have a problem?!

FreeBear

Three issues here...

1) The UFH should have been turned off and left off for at least two weeks to allow the adhesive to cure properly. Having it dry out too quickly will lead to a weak bond.

2) The tiler failed to back butter the tiles (recommended for all large format tiles) and it looks like the mortar bed is too thin for the size of tiles.

3) A 3mm grout line is generally way too small for 600x600 tiles - I think you'll find the manufacturer will have specified a 5mm gap.

See what others have to say first, but my impression is it is a poor job resulting in cracked/lifting tiles within a year.

andyhop

The tile should b sat on a solid bed of adhesive, not dabs. These will crack and fail in weeks

3mm grout line is more than ample, with a decent S2 adhesive you could go down to 2mm

The biggest isssie is the concrete, this dries at a rate of around 1 inch per month. Was it concrete or a flexible screed? Decoupling membranes can be used to fast track but I don't see that either

chris1012

andyhop wrote: »

The tile should b sat on a solid bed of adhesive, not dabs. These will crack and fail in weeks

3mm grout line is more than ample, with a decent S2 adhesive you could go down to 2mm

The biggest isssie is the concrete, this dries at a rate of around 1 inch per month. Was it concrete or a flexible screed? Decoupling membranes can be used to fast track but I don't see that either

They initially put down concrete (4.3 weeks ago) then put the wet under floor heating pipes and then screeded on top.

Not sure about the flexibility of the screed

theonlywayisup

We have UFH throughout our barn conversion with a French limestone floor. The screed was completely covered with a Ditra matting, the tiles were laid on the Ditra. We haven't had a single crack or issue and it's now 12 years old. Previously we didn't know about Ditra and had big issues with tiles cracking.