Water under tiles in a tiled shower

Good morning,

we have a problem with water behind the joints in our shower, but our tiler is not very understanding about it. Maybe someone has experience with this issue and can give us an assessment before we contact an expert:

- The shower in the guest bathroom has been used a total of 5 times since we moved in, so it cannot be wear and tear.

- The joints in the showers on the sides (transition from floor to wall tile) came loose and salts (?) are emerging there. You can see in the photos that near the silicone joints, the regular tile joints are also noticeably darker, which in our opinion indicates moisture.

- We informed the tiler about the problems and he said these were maintenance joints, so not a case for a complaint, but he would redo the joints. Then he applied a new silicone joint on top of the old one, which came loose immediately after one shower (silicone on silicone obviously did not hold). The dark spots on the tile joints were still there several weeks after the last shower. When pressing on the new joints, water also came out of the joints.

- As mentioned, since the new joints came loose from the old ones and the old joints are already damaged, I removed the silicone to redo the joints completely. While doing that, we could see that water had collected behind the joints and there were large cavities there. A piece of paper pushed between the joints immediately absorbed water as well.

- This means that the joints let water through, and water collects in the cavities. If water continues to collect there and cannot dry out (because it is behind the silicone joints), we will have water damage here within a very short time, right?

Is that normal? In our opinion, it should be sealed there in such a way that no water can collect?

Thank you in advance if someone can provide an assessment.

1. How old is the bathroom?
2. Silicone joints are actually only maintenance joints and do not ensure the watertightness of the shower.
3. Behind the tiles there should be a waterproof coating that prevents water from penetrating the walls. Therefore, the joints do not need to be waterproof.
4. Redoing joints (even if done by the tiler) actually means removing the old ones and then regrouting.

Make a deal with the tiler. You scrape out and he reseals completely once. Or get someone who does this professionally. Many tilers cannot do this properly.

1. How old is the bathroom? 2. Silicone joints are actually only maintenance joints and do not provide the shower’s watertightness. 3. Behind the tiles there should be a waterproof coating that ensures no water can penetrate into the walls. Therefore, the joints do not have to be waterproof. 4. Re-doing joints (even if done by the tiler) actually means removing the old ones and then re-jointing.

Make a deal with the tiler. You scrape out and he reseals completely anew. Or get someone who does this professionally. Many tilers actually cannot do this properly.

Thanks for the feedback!

1. The bathroom was tiled in February 2023, we moved in March.

2. Shouldn’t the joints at least last longer than 5 showers?

3. I understand that, but if there are such large cavities where water collects and cannot drain, won’t a moldy, stinking broth accumulate there over the years? Shouldn’t the tiler work in such a way that the adhesive fills the cavities so that liters of water don’t stand there?

4. Yes, we thought so too... That a tiler puts a new one onto the old, damaged one is really sad...

Thanks for the assessment.

With this attitude of the tiler, I fear the worst. New build and move-in March 2023 or renovation?

Are there pictures showing the bathroom in the shell condition or during construction, especially regarding the sealing UNDER the tiles mentioned above?
If this is missing, a new silicone joint won't help either! Even the non-silicone joints are not 100% tight. So if no (double) waterproof coating has been applied, the sealing tapes and collars have been omitted, this is a nice case for demolition :-(
Otherwise, really big damage to the house has to be feared ...

With this attitude of the tiler, I fear the worst. New build and move-in March 2023 or renovation? Are there pictures showing the bathroom in the shell condition or during construction, especially regarding the waterproofing UNDER the tiles mentioned above? If this is missing, even a new silicone sealing won't help! Non-silicone joints are also not 100% watertight. So if no (double) waterproof coating has been applied, and the sealing tapes and collars have been omitted, this is a nice case for dismantling :-( Otherwise, really major damage to the house is to be feared ...

It is a new build. No, unfortunately I have no pictures of the shell condition and cannot say whether it was properly waterproofed. I have meanwhile lost all trust in the tiler. Is there a way to subsequently find out whether it was waterproofed? Other than removing tiles and checking underneath?

First, I would check the slope in the shower towards the drain. Use a small spirit level and check if the water does not flow against the drain or even stands there.

At the connection between the floor and the wall at the back, I would glue a rail instead of the joint using body adhesive Sika Flex or similar.
Then the connection would already be sealed. I would also seal the other connections with body adhesive instead of silicone.

There are semi-circular sealing rails for the corner area.



But first check the slope, otherwise everything else makes no sense.