Water on ground slab, cause and leak unknown

  • Erstellt am 2018-03-21 10:39:02

ibo85

2018-03-21 10:39:02
  • #1
Hello,

I am reaching out here because I am quite desperate and cannot find a solution to my problem myself.
Background:
In 2015, I had a house built. I managed the construction myself and hired all the trades myself. By the way, the shell construction company no longer exists at the moment --> bankruptcy.
The house has a basement that is about 2m below ground level and thus protrudes about 1m above ground.
The floor slab was poured in one piece. Afterwards, precast wall elements were installed --> [Weiße Wanne].
At the time, there was groundwater about 10-20 cm high in the excavation pit. So still below the floor slab.
The joints between the precast elements were sealed with bitumen. Sheets were installed between the wall and the base plate, and cast-in-place concrete was poured into the precast wall elements.
One year after construction ended, in spring 2016, the wall paint on an interior wall peeled off along a horizontal line about 20-30cm high and bubbles formed. At that time, I hired a company to get to the bottom of the matter, but unfortunately nothing was found. What was done was breaking two tiles down to the floor slab. The floor slab was a bit damp, that was all, the cause could not be found.

Now, almost 2 years later, the same bubbles have formed again on the same wall, and the plaster on an exterior wall is wet up to about 1m height.
As a result, I removed a tile at another spot and broke out the screed down to the floor slab.
There I discovered about 2cm high water. I first sucked it out with a wet vacuum. However, this unfortunately does not help because exactly this approx. 2cm high water level always re-forms.
To find out the cause, I did the following:
1. There is a drainage around the house with a shaft that I can open at ground level. I opened it to see the groundwater level (the drainage lies below the level of the floor slab) - completely dry, no water. Although I have to say that the shaft is located on the other side of the house, so not where the wall is wet.
Question about this: Could it be that the groundwater level is higher on the other side of the house? The house is not on a slope or anything like that.
2. I poured water-based dye into the wastewater pipes to see if anything was wrong with the sewage and then observed the spot where I see the water (opened spot inside the house). Nothing!
3. I checked the main water meter; it shows minimal flow rates. Completely still.
4. The basement is heated with underfloor heating. The heating circuit has a constant pressure of about 2 bar. No change.

I am desperate because I simply cannot be sure where the water is coming from. It is interesting that - no matter how much water I suck out - the level of about 2cm always sets itself again. That would also suggest groundwater, but there is not a drop of water in the shaft, it is not even damp.
No movement in the main water meter, no pressure drop in the heating circuit, no dye from the tested wastewater.

Since I just built new, financially I am not strong at the moment. Because the shell constructor is bankrupt, all costs fall on me.
I would like to hear from you what ideas you have and would accordingly pursue the cause.
At the moment, there is no suspicion that would narrow down a cause, which is why I do not want to hire a leak detection company.
They couldn’t find anything in 2016 either.

I hope you have ideas or experience on what I might pay attention to in order to find the leak and what is most likely.

Thank you very much in advance for your answers.
Regards
 

Curly

2018-03-21 10:48:07
  • #2


I don’t understand that, why is the groundwater 20 cm below the base slab?

Best regards
Sabine
 

Maria16

2018-03-21 10:56:29
  • #3
Can you follow up with the leak detection company from back then regarding the warranty on their part? I mean, ask them to search again at no cost to you?
 

ibo85

2018-03-21 10:57:37
  • #4
Under the floor slab there is a base layer of coarse natural gravel, then comes a layer of insulation about 10 cm thick. And during construction the groundwater was still below the level of the floor slab.
 

ibo85

2018-03-21 10:59:57
  • #5
I don't think so. At the time, I signed the report prepared by the company. It's also not about small costs up to 500 euros. If I could be 100% sure that the leak would be found, I would also be willing to pay 1000-1500 euros. But that's not the case.
 

niri09

2018-03-21 11:07:41
  • #6
I am not an expert, but maybe one could hire a geologist who measures the groundwater level next to the house (maybe even around the house). My feeling would rather be on the groundwater, which can also change.
 

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