Damp behind shower tiles - again!



Hi all.

I need some suggestions or advice if you could be so kind. Back in November, I posted to these forums about a problem in my shower cubicle in which the bottom 3 rows of tiles (200mmx200mm, all white) had turned a shade of blue. It turned out the wall behind the tiles was wet and it appeared the wet got in through a small crack in the grout.

I removed all affected tiles, plus the row above which was not wet (for good measure) and let the walls dry out. Then I contacted a tiler who re-tiled it for me, and said it was good to go once the grout dried etc. The other side of the walls, which had previously shown mould and bubbling paint were re-plastered and all was well.

In the last few weeks I've noticed the same tiles turning blue again - argh!! Plus the other side of one wall is showing mould and the other is bubbling up again. I can see it's only a matter of time before the problem gets as bad as it was in November.

What would cause this to happen? I see no breaks in the sealant or grout (but there does now appear to be mould behind the sealant!). Is this likely rising damp that was never treated and has returned, or is it more likely to be a leaking pipe under the shower tray? What should I do? Remove the tiles and get it re-tiled again? Just leave it as-is for a few weeks to dry out? I cannot afford to have the whole unit replaced.

Thanks for any suggestions.

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I don't know... I didn't know there was such a thing as non-waterproof grout! I assume he would have used waterproof grout as he was a tiler and he knew the problem we had had with the damp etc. Also, the damp problem has only appeared to return in the last few weeks, so for 6 months it certainly appeared dry and fine. Surely if the grout was not waterproof it would have shown damp pretty soon?
ordinary grout lets the water soak thru.
& so will waterproof grout; it’s a commonly held misconception but it's only waterproof in the sense that it won't disintegrate when it's wet, it’s not impervious to water unless you use one of the very expensive epoxy grouts.

Wasn’t involved with your original thread but I’ll have a look through & see if I can add anything. Do you know what adhesive & grout he used?
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