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Discuss Help! Tiled wetroom floor looks perfect but grout doesn't dry out! in the Tanking and Wetrooms Forum area at

  1. Paula

    Paula Active Member

    We had a wet room installed about 8 months ago. The floor is tiled with large 60x60cm porcelain tiles laid on Impey Waterguard membrane and the shower tray is Impey Aquadec Easyfit with the membrane laid over the top. It is a new-build first floor bathroom (new extension on older house) with a suspended timber floor. The tiles appear to be laid well and there has been no obvious movement or cracking of grout (Bal Micromax). However, almost immediately we noticed that in the shower area some areas of grout (which is light grey) did not dry out, and over time about 50% of the grout lines were permanently dark, even when the shower was not used for a few days. I searched tiling forums and became concerned that the tiles had been laid on an incomplete layer of adhesive, and that water was pooling underneath them, leading to permanently wet grout, but could not see any evidence of the tiles coming up or moving about, which usually seems to happen with problems like this.

    Our builder called back the tiler who swore that he had used the correct amount and type of adhesive, and said that if he had not done so then the grout would have cracked on the floor. Bal, the grout and adhesive manufacturers, were called, but their "expert" tried to claim that the dark patches were not, in fact, wet, but possibly mould or even dirt! He agreed that it looked like the tiles had been correctly laid and suggested leaving the floor to dry and then replacing the grout and then using a sealer to stop water soaking through the grout. When I mentioned the possibility of adhesive not covering the back of the tiles, he agreed with the builder that it was very difficult to achieve a completely flat bed of adhesive, suggesting that it was almost inevitable that some pooling of water under the tiles would occur, leading to patches of wet grout.

    We agreed to wait for the floor to dry out. We are now on week 5 (in a warm room with underfloor heating in the rest of the floor away from the shower tray!) and there is still a small wet patch, but most is back to the normal light grey colour. It took about 3 weeks for most of the moisture to go and the dark patches to disappear, so we have now discounted the mould/dirt theories, but are concerned that there must have been quite a lot of water sitting under the tiles for them to remain wet so long! The builder now just wants to seal the dried grout, and not re-grout at all. He is refusing to do anything else.

    I have talked to most of the manufacturers of grout sealers, and they all say that their products will not completely waterproof grout, so I cannot see that this will be a long-term solution (also, don't fancy waiting for the floor to dry out each time it needs re-applying!). Epoxy grout seems like a good idea, but the builder seems to think that it would eventually crack if used on a timber floor (although when I spoke to Mapei about Kerapoxy they said that it should be fine as long as the floor is not bouncing around a lot, which it is not).

    What I'd really like advice on is:

    - is it normal to have permanently wet patches in grout on wet room floors even if the floor appears to be well laid?

    - if we leave the floor as it is, will we be storing up trouble for the future? Am I being too fussy??!

    - Is it possible to lay tiles in a pre-formed shower tray on a completely flat bed of adhesive, or will there always be gaps for water to collect in?

    - Should we consider a grout sealer or epoxy grout to solve the problem or do the tiles need taking up and re-laying? (massive Job I imagine as
    there is a huge glass shower screen resting on one grout joint and the membrane may be damaged in the process?)

    It does feel like I am being fobbed off by the builder and the tiler, but admittedly the wet grout patches are the only problems so far. It would be great to hear from anyone who has had similar problems. I can't quite see the point of having tiled shower trays if they always look different to the rest of the tiled floor!


    Last edited by a moderator: May 27, 2015
  2. Andy Allen

    Andy Allen Forum Entertainer! Trusted Advisor Professional Tiler JOTM Winner Top Contributor

    Grout will soak up water and change colour as it's not fully waterproof, providing everything has been tanked , theres no loose tiles then it is what it is im afraid. .
  3. Unregistered

    Unregistered Guest

    Hi Andy

    thanks for the quick reply!

    So are you really saying that tiled shower trays always look like they have wet patches of grout, then? This would certainly be the case with ours under normal use (two showers a day) given that it takes 4 weeks for all the wet patches to dry. If so, I'm glad I opened this thread, as I would definitely want to warn others considering installing tiled trays and using grey grout (perhaps it isn't as obvious with white or cream?) that the floor will always look different to the rest of the bathroom. It looks really messy I think, as not all the grout remains wet, and on first glance could even be mistaken for mould!

    I will try and post a couple of pictures of the shower tray after various periods of drying just to check if you still think that is normal.

    Thanks again,

  4. cam_low

    cam_low Professional Tiler JOTM Winner

  5. SJPurdy

    SJPurdy Professional Tiler

    If the grout is filling the joints and there are no bits missing then I think it unlikely that sufficient water has permiated through it to fill any small cavities in the adhesive layer (if there are any). As already stated many grouts (even white and light coloured ones) change there shade slightly when they are damp (due to some water absorption) - this much less now with the modern modified (CG2) grouts. I am baffled by why only some of the grout "50%" remains dark in the wet area. Look closely at these joints to check that there is no (microscopic) cracking along these grout lines. I have experienced the grout joints between mosaic sheets taking longer to dry out than the joints between the 'mosaic attached to the mesh backing' when fitted over the self adhesive flexible black water proof membrane (that I think was Impey) and I deduced this was because the membrane remained compressible and the point loading on mosaic caused 'only jut visible' cracks in the grout and these took longer to dry out. No one has reported to me this problem when I have fitted larger porcelain tiles (but it would be less visible as the wet and dry joints would be further apart).

    I think using a wet room twice a day you are always going to have dampness in the wet area grout which is why the substrate underneath must be tanked. Different brands of grout will have more or less difference in there wet/dry colour shade. Sealing over the grout when dry may prevent/lessen the water absorption of the grout - In my wet room I do not notice any colour change in the grout when wet ( I haven't specifically looked for it) but it has been sealed along with the natural stone mosaic so the water pools on the surface. In your case I think that if there are no faults/cracks in the grout then I would try using a sealer over the grout (when dry) to see if this improves things before doing anything more drastic.
  6. Paula

    Paula Active Member

    thanks so much for your considered thoughts, SJPurdy: it's great to hear from someone who has experienced similar issues. My grumpy tiler has come back today and liberally sprayed a can of sealer (Vitrex?) all over the shower floor and told me to wait for 24 hours before using. I've tried to take photos of the grout….but even though I tried to make them smaller this time, I still can't get the hang of uploading them. I have taken Cam up on his very kind offer of posting previous pictures of the shower for me, so I will email him photos of grout in the problem areas too and ask him to upload them, too. To my untrained eye there isn't any obvious cracking, but I'm sure you will be able to see if there is a problem.

    If you think we shouldn't start using the shower again so soon, then please let us know, as it takes ages to dry out!

    Thanks again,

  7. cam_low

    cam_low Professional Tiler JOTM Winner

    P3240070.jpg P3240071.jpg P3240072.jpg
  8. Lithofin BOB

    Lithofin BOB Company Support

    As above ,the application of an impregnating grout sealer should ease the issues , you will need to ensure that the grout if fully released of all moisture before application, you will then need to maintain this impregnating product as well as your tiles with a suitable porcelain cleaner. this will clean the tiles but also look after the protector,as general household cleaners and also residues of shampoos, conditioners ect can start to break down this extra protection . When finishing showering ,is there excess water on the surface of the grout and tiles, although extra work , squeegee this away and towel dry for extra longevity of the product and quicker evaporation of this sitting water.

    Question for the guys,girls on here, if a grout was over washed in areas at installation , would this effect the water reppelance built into the grout in some areas , over wetting the polymers possible removal and then wetting deeper in areas and not others? Or possible if it was mixed to dry and had not hydrated the mix completely ?
    • Like Like x 1
  9. Stef

    Stef Professional Tiler

    Cumnock, Ayrshire
    That grouting is cracked.
    I'm on my iPhone so can't get a good close up of it.
    I read this thread earlier & the way it was described it was sounding like the tiles were dabbed onto the tray.
    • Like Like x 1
  10. Lithofin BOB

    Lithofin BOB Company Support

    Is that cracks and small holes cam, you may have on a larger pics
  11. Paula

    Paula Active Member

    Do You want me to send larger pics? Those above were made smaller to email to Cam, but I can send him larger ones? He also has pics of the whole shower tray at various stages if you think that would be helpful (I'm afraid whatever I do, I can't seem to use your system for uploading!)

  12. John Benton

    John Benton Trusted Advisor Professional Tiler JOTM Winner

    Concur with Stef there. I've blown up the images and it does appear that the grout has cracked along the side of the tile. The tray although having a gradient to allow water to flow to the drain there is no reason why you cannot get a full bed of adhesive beneath the tile as the gradients are perfectly flat.

    Do you know the method used for fixing the tiles, even in the dry area of the floor i.e. was the right size notched trowel used and were the tiles back buttered with adhesive prior to fixing. A good way of telling if they were is to tap on the tiles with your knuckles at various different points and if the sound is hollow then there is a chance that water could sit beneath the tiles in any voids left. If there is a hollow sound then chances are they were just dot n dabbed to the floor. This is the wrong fixing method and although possibly not visible to the eye there may be a small amount of movement but enough to crack the grout and allow water to directly pass the grout and sit underneath.
    • Like Like x 1
  13. Paula

    Paula Active Member

    Thanks for this, John

    The tiler is adamant that he correctly buttered the tiles, and that there should not be any voids underneath, although he says that the fact that the tiles are still stuck down and the grout is not obviously cracked must mean that he has bedded them down properly, which you seem to suggest may not be the case?

    Are you sure you can see cracks, and not just darker lines along the grout? I'm happy to email you larger pics just to be sure? Let me know.

    When tapped, there is no obvious hollow sound (unlike on our kitchen floor, which he also did, but that's a different story!). He is also a plasterer, so well used to "dotting and dabbing" I would imagine, but claims not to have done here and as I wasn't standing over him I can't comment on what he did.

    Thanks for taking time to reply, I really appreciate this.

  14. cam_low

    cam_low Professional Tiler JOTM Winner

    1.jpg 2.jpg 2.jpg
  15. cam_low

    cam_low Professional Tiler JOTM Winner

    aye looks like a regrout is in order, firstly leaving the shower for a week or so for any sitting water to evaporate, maybe two weeks to be sure. However if dot and dabbed, this may not be a long term solution, or it may work out fine, you just never know when its not done correctly.

    ps sorry for the delay, just got in from my first powerleague game. Im well unfit and tired !
  16. Dash J

    Dash J New to

    I always use epoxy on my wet floors
  17. Paula

    Paula Active Member

    thanks, Bob. We have now sprayed on a sealer, but to be honest I chose porcelain rather than natural stone tiles to avoid maintenance, so it's disappointing to hear that I will now have to seal the grout at regular intervals! If there is any way of avoiding this, I would rather do that…unless you are saying that everyone who has a tiled shower tray should seal the grout regularly? This is certainly not publicised by bathroom designers or tilers in general: perhaps it should be, then?
  18. Paula

    Paula Active Member

    Thanks, Cam, but why do you say to re-grout: do you also think that the darker lines are cracking? They just look like lines of darker pigment to me. I know I'm going to have an uphill battle to convince the tiler and builder on this, as they have both stared and it and declared that there is no cracking at all (as did the BAL "expert"!). I need some ammunition if I'm going to go down this route!

    Is it worth you uploading any of the other photos I sent you?

    thanks again,

  19. John Benton

    John Benton Trusted Advisor Professional Tiler JOTM Winner

    If you could try and upload closer photos of the grout joints just to be 100%, It did look like fine cracks.
  20. Paula

    Paula Active Member

    DashJ, would you recommend this on a suspended timber floor? Builder seems to think this would be a no-no for us, even though there is no obvious movement of tiles/floor at the moment
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