Is water damage on an internal wall or something else?

[UrVeggieMate]

I'm someone who doesn't have a lot of home maintenance knowledge. I put the pictures into Google Lens to find similar instances online and the results indicated that it could be a result of water damage to the wall.

I turned off the water at the mains earlier this week before going to work for a 7.5 hour shift, no change in the readings. I also can't hear anything in the walls that might indicate a burst pipe but again, not a lot of home maintenance knowledge, so I'm not 100% sure.

I suspect that the other culprit could be grout wearing out and water seeping into the wall that way, although any cracks I can see in the grout are hairline only. Not sure if this would make a huge difference.

House is 8 years old from time of construction. Cracks are only at the bottom of the wall. The rest of it is fine.

It feels crusty and almost rock-likeDamage where the wall meets the carpet

All the above images were taken on 22/07/24. Today on 27/07, I noticed the below, which wasn't there before as far as I know. 

If anyone knows anything or has experienced something similar, your help would be greatly appreciated!!

[UrVeggieMate]

Hi Jacob,

The plumber came and did the pressure test today. The good news is that there's no leaks. He said that by the height of the damage, he didn't suspect it would be pipe related. This would take us back to grout failure and/or faulty waterproofing being the culprits, but more likely the grouting. 

Would you be able to recommend a good waterproofing sealant to paint over the top of the tiles once I've redone the grout?

Thanks again for all your help. 

[MitchellMc]

Hi @UrVeggieMate,

To clarify what my colleague @JacobZ touched on earlier, unfortunately, it does appear that your waterproofing membrane is compromised. Its job is to stop water that weeps through grout lines (as they are not waterproof) and direct it to the drain. So, even if you have cracks in your grout, the membrane should still direct the water to the drain. If moisture penetrates the wall on the other side, it indicates that the membrane is not doing its job. You can add a grout sealer, which might offer a band-aid solution, but the real issue is that the membrane is not functioning as intended.  

You can have a leak test done on the shower to determine if the membrane is comprimised. They'll block the drain and fill the base of the shower with water. A fluorescent dye is added to the water and then an ultra-violet light used on the other side of the wall to detect leaks.

Please let me know if you have any questions.

Mitchell