Grout cracking - underfloor heating?

QTPie

Hi

Any advice?

We bought a house last March. The house was extended 5 years ago (previous owners). The extension includes our bedroom and en-suite. The en-suite has underfloor heating (installed when the extension was done).

I noticed, at the time we moved in, that there was some minor chipping in the grout (little stretches of grout broken away and missing) and signs of previous patching (ie small areas of lighter coloured grout).

Have recently turned the underfloor heating on (didn't feel necessary for most of the year). I am seeing further breaking away of grout and also cracks opening up along the grout lines. Was also hearing a "tapping" sound coming from under one of the tiles last night. Have now turned the heated floor off.

We have had underfloor heating before - had it installed several houses ago. I remember talk from the, excellent, tradesman about using flexible grout to prevent cracking. So should our grout be cracking? Is this normal (after 5 years) or is it likely that a standard grout was used (instead of a flexible one which should allow for expansion and contraction due to the heating)?

What options do we have? Patching seems a bit futile (at least if you want to USE the heated floor) - because it will just chip and crack along other lines. Can the floor be re-grouted (can the existing grout between the tiles be removed and replaced with flexible grout?)? Or do we have more problems that that - would the grout fixing the tiles to the floor below also possibly be an issue?

Wondering if this can be fixed (without ripping up the whole floor - and then having to replace all of the tiles and presumably the heating elements etc too, I assume that they would be destroyed by pulling the tiles up)?

Thanks
QT

brightontraveller

Could be they used standard grout / adhesive or both instead of flexible can and often does crack with underfloor heating you could try re grouting with flexible as to removing tiles damaging underfloor heating that would depend how the laid how easy tiles come up etc e.g. directly onto floor screed then adhesive or under floor screed etc

Spicy_McHaggis

Is it electric or hot water heating?

I would guess that if they've not used the correct grout then the wrong adhesive will have been used too.

You could try scraping out the grout and redoing with flexible grout, if the cracking comes back the floor will need to come up.

If the floor comes up,and you have electric heating allow for a new mat.

phill99

There are a number of possibilities as to why the grout is cracking.

Firstly, the floor may not have been overboarded (either with a concrete based backing board or ply) prior to installation. There are rigid insulating boards that can be used with underfloor heating, also.

Secondly, as you suggest a non-flexible adhesive may have been used.

Thirdly, again as you suggest, a non-flexible grout may have been used.

If it's the grout, you could regrout, but thete is a risk that when removing the old grout you could easily damage the heating cable.

My gut feeling is either the first or second as even if a flexible grout had been used, it would still crack if the tiles were moving.