We are going to regrout our shower tiles due to some cracks since the technical inspection said it was leaking into the wall which could cause water damage. We removed one soap holder and it seems that there has been leaking water behind it, it was a bit rusty and maybe even molded. Now there are two deep screw holes (see photo).enter image description here Can we just fill them with grout as well or should it be a different filler? The wall behind is concrete. Do you recommend using a professional for this job or can we just do it ourselves? Worrying a bit for insurance if there is water damage later.


When you re-grout the stall, presumably you will use a mildew remover to get rid of the dark lines that may be left over after the old grout is removed. While using the mildew remover, use a small brush to get the remover deep into the holes of the screws, yes you must have had some leakage there. This must be absolutely clean of mildew and soap scum/residue before grouting or the mildew will grow back out of the grout joints and the screw holes. The soap scum will prevent the grout from sticking the way it needs to as well.

Rinse everything really well. The little bit of water that will get through will be no different that the leaks before. Since this is part of doing a thorough job, this will...hopefully be the last time it gets wet from leakage.

Grout everything, including the screw holes. when wiping down, the grout will recess a tiny bit. Let everything dry for 2 days, check to see if the screw holes are acceptable as they are. If not CAREFULLY, fill and level with caulk. Let dry. If that is acceptable, seal everything with a silicone based tile and grout sealer.

  • Thanks. Actually the black lines were just a result of us using the wrong head on the grout removing tool, they are metal coming off from the head, now we have the right one and it is gone...in the screw holes though it could be mildew but maybe just dirt/old glue, hard to tell, but we are cleaning with vinegar now just to be sure. What do you mean by using a grout and tile sealer? On top of the grout? Why is it not enough to just grout it? Or is that only if we use caulk? May 25 '20 at 10:46
  • Also, since the wall behind is concrete would it make sense to fill the deeper part of the hole with a joint filler? May 25 '20 at 10:48
  • I do not know what you mean by joint filler, other than grout, which is a joint filler. Grout for the joints is not waterproof, it is water resistant but will still let water pass through. Sealing the joints after grouting will minimize the amount of water entering the joints and reduce mildew too. The caulk I mentioned was for the immediate area of the screw holes, only if the grout in them was not satisfactory.
    – Jack
    May 25 '20 at 14:28
  • Thanks a lot again, one final question do you think there is a risk that mold/mildew is growing behind the tiles and is there a risk of filling the holes/regrouting without checking that thoroughly? Because I see some black stuff on the bricks inside the holes but of course I don't know what is going on behind the tiles... May 25 '20 at 23:50
  • In all my years of construction, I have never seen mildew behind tile work. I have seen it in the wall cavity that the tile work was on but only because there was a bad shower pan or missing grout, cracks, what have you. If everything is in good shape, and it sounds like you maintain your shower well, I would not draw any concern about mildew. The black stuff outside the tile, is all it should be since it was harboring in a tight place where moisture was trapped.
    – Jack
    May 26 '20 at 0:05

I'd be inclined to either: fit another soap holder; remove the offending tiles and replace; fill the holes with grout, making sure it does more than plug the surface.

With idea 1, put silicone in the holes first, then the screw plug (deeper than the tile, please!) and screw holder on, with a touch of silicone to finish.

With idea 2, there's always a chance you can't get tiles to match, but if yiu can, it's the best option.

With idea 3, putting enough grout to seal the hole won't be difficult, but there will always be two blemishes on the tiles that won't go away.

  • Thanks, if we go for 3 would it make sense to first fill with a joint filler we usually use for our walls before painting? Since the screws penetrate into the wall behind May 25 '20 at 10:49

I removed the worn out shower doors from the bathrooms in the older house we bought. That left the holes in the tile. I opted to fill them with caulk. Since your tile is white it's easy to match and it would barely be noticable.

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