Possible water leakage issue

[Gardenboy]

I am going through an issue and can't understand the possible cause of the issue. The wall next to my bathroom stays slightly wet and the paint always peels off. I have tried repainting and have call the plumber many times, but they can't find any leaks in the washroom. What could be the possible reasons? Why my wall is always slightly wet?

I know there are water pipe/pipes going through that wall because the basin for washing hands is installed just behind this wall. I can't tell if the bathroom side of the wall has same issue because it is tiled.

Any suggestions and possible causes of the issue would be helpful, thank you!

[TinyTool]

Hi there!

Is this affecting the whole wall or just part of it?

[Gardenboy]

Thank you for the prompt reply TinyTool. Mostly bottom of the wall.

[TinyTool]

Thanks for the clarification! Since the moisture issue is mostly affecting the bottom of the wall, it could suggest a few specific causes:

1. Leaking Drain Pipe or Waste Line: Even though the plumber didn’t find any leaks, the problem could be related to a slow leak in the waste line or drain pipe, which is harder to detect. The water could be seeping out at the bottom of the wall where it settles.

2. Capillary Action (Rising Damp): If the moisture is coming up from the ground, it could be due to rising damp, where water from the floor or foundation gets absorbed by the wall. This is more likely if you have a slab foundation or if the bathroom floor itself isn’t properly waterproofed.

3. Poor Sealing Around the Basin or Floor: Water could be running down from around the basin or floor when in use, settling at the bottom of the wall. Even if the plumbing is sound, water might escape from small gaps in caulking or tiles, eventually collecting at the base of the wall.

4. Condensation Near the Floor: As cold air settles near the floor, condensation might occur at the bottom of the wall, especially if cold water pipes are running through that area.

Given that the issue is concentrated at the bottom, it might be worth rechecking the sealing around the basin and the base of the wall for any gaps. A moisture meter could also help detect how high the moisture is rising and where it’s originating from.

Would it be possible to remove a tile or check underneath the basin for potential leaks?

[Gardenboy]

I called a professional and he already broke some tiles and checked the basin pipes for leaks.

[TinyTool]

Since the professional has already checked for leaks behind the basin and removed some tiles, it further suggests that the issue might be related to hidden moisture sources or structural issues. Here are a few things you could explore next:

1. Inspect the Drain System: Sometimes leaks can occur in the drain system rather than in the supply lines, which may not always be obvious with a quick inspection. A slow leak in the drain could be hard to detect and may only leave moisture near the bottom of the wall.

2. Check for Floor Waterproofing Issues: If water is pooling near the base of the basin or along the floor during use, it could be slowly seeping into the wall from below. Ensuring proper caulking or adding waterproofing at the floor level might help.

3. Foundation or Floor Moisture: If your home has a slab foundation, moisture could be wicking up from below, especially if the bathroom isn’t properly sealed at the base. A foundation or waterproofing specialist might be able to help identify if rising damp is an issue.

4. Ventilation and Humidity: Inadequate ventilation can cause moisture to build up in bathrooms, especially near the lower parts of walls where air circulation is poor. Consider evaluating your ventilation system to ensure moisture is being adequately expelled.

Since plumbing leaks have already been ruled out, addressing floor waterproofing or rising damp could be the next steps.

[Gardenboy]

Hmm thanks. I am suspecting as my bathroom is tiled, there might be some water going through the gaps between the tiles. Can you recommend a good way to completely seal off these gaps to stop water? I am not sure but I think currently the gaps are filled with white cement.

[TinyTool]

If the gaps between your bathroom tiles are filled with white cement, it might not be fully waterproof, which could allow water to seep through. To properly seal off those gaps, you’ll want to replace the white cement with a better solution, like epoxy grout, which is both waterproof and durable. Start by carefully removing the old material between the tiles using a grout removal tool. Once the gaps are clear, apply a high-quality epoxy grout or polymer-modified grout—these are designed to withstand moisture and prevent leaks. After the new grout has dried, it’s important to seal it with a grout sealer, which will add extra protection against water. Also, check the areas where the tiles meet the walls or floor and use silicone caulk to seal any joints or corners. This should help prevent water from getting through and stop the moisture from affecting your walls. If you’re not familiar with grouting, you might want to consider bringing in a professional to get it done right.

[Gardenboy]

Thanks for the advice Tinytool!