Moving tiles - can I use a very flexible grout?


16 Feb 2016
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United Kingdom

About a year ago I had a new 6m x 6m kitchen extension. The porcelain tiles are 80cm x 80cm, and over both the concrete floor of the extension as well as the wooden floor of the old part of the house, and over underfloor heating. We put detra mat down over the whole area, but the tiler used a very thick layer of adhesive...not sure if that makes a difference. Between tiles is about 2-3mm of Norcros flexible grout.

Across the whole floor the grout started cracking and coming out of the gaps, beside some tiles more than others. The builders came back to rout out the grout and replace, but it happened again almost immediately. I can hear a couple of the worst-affected tiles are moving slightly when walked upon, and I'm not sure if the grout on the other tiles are expanding/contracting or also moving to a lesser extent. I can't replace the whole floor...but would a very flexible grout such as Granfix's 'Ultimate flex' grout (suggested on another query) do the trick do you think? Is it more flexible than Norcros flexible grout?

Many thanks!

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I think you have a big issue with the original installation! A number of factors would need considering. To start with the quality of materials and method of installation, if the tiles are moving in a manner that causes your problems.
It is likely the adhesive depth is not allowing the product to set. Is the problem occurring on the concrete or timber floors? I would have put 5mm-7mm spacers in!

Thanks for your reply. The grout is cracking across both parts...although the two tiles that I can hear moving are on the wooden part. Most of it is not too bad...hairline cracks and the grout has not come out...but the four or so tiles where it's worst, the grout has come out around a couple of seems. I agree it is probably the depth of adhesive, and the spacers are too small.
Bringing up the floor and replacing isn't an option right now, and as it's not too bad, thought I would at least see if a more flexible grout would work. Do you know if the
Norcros flexible grout that is cracking would be less flexible than others?

Many thanks
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were any expansion joints installed?
how much gap was left between the tile and the wall all the way round the perimeter? (and what was it filled with?)

Do you have any loose tiles that you can lift and send an image of the floor beneath and the backside of the tile?shouldn't be a problem to re-fix

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