ᐅ Water on the foundation slab – cause and source of leak unknown
Created on: 21 Mar 2018 10:39
I
ibo85Hello,
I’m posting here because I’m quite desperate and can’t find a solution to my problem on my own.
Background:
In 2015, I had a house built. I managed the construction myself and hired all the tradespeople directly. Meanwhile, the shell construction company no longer exists — they went bankrupt.
The house has a basement about 2 meters (6.6 feet) below ground level, with approximately 1 meter (3.3 feet) of it above ground.
The slab was poured in one piece. Afterwards, precast wall elements were installed — a “white tank” waterproofing method.
At the time of construction, there was groundwater in the excavation, about 10–20 cm (4–8 inches) high, so still below the slab.
The joints between the precast elements were sealed with bitumen. Metal sheets were installed between the wall and the footing, and in-situ concrete was poured into the precast elements.
About a year after completion, in spring 2016, the interior wall paint peeled off along a horizontal line approximately 20–30 cm (8–12 inches) high and blistered. I hired a company to investigate the problem, but nothing was found. They broke two tiles and checked down to the slab. The slab was slightly damp, but that was all; no cause was found.
Now, nearly two years later, the exact same blisters have appeared on the same wall, and plaster on an exterior wall is wet up to about 1 meter (3.3 feet) high.
I then removed a tile in another spot and broke up the screed down to the slab. There I found about 2 cm (0.8 inches) of standing water. I first removed this water with a wet vacuum cleaner, but this makes no difference, as the water level of about 2 cm (0.8 inches) always returns.
To investigate the cause, I did the following:
1. There is a drainage system around the house with an access chamber that can be opened at ground level. I opened it to check the groundwater level (the drainage is below the slab level) — completely dry, no water at all. However, I have to mention the chamber is located on the opposite side of the house, not where the wall is wet.
Question: Could it be that the groundwater level is higher on the other side of the house? The house is not located on a slope or anything similar.
2. I poured colored dye into the wastewater pipes to see if there is a problem there, then watched the spot in the house where I see the water (the opening). Nothing appeared.
3. I checked the main water meter; it shows only the smallest flow rates, completely still.
4. The basement is heated with underfloor heating. The heating circuit maintains a constant pressure of about 2 bar (29 psi) with no changes.
I’m desperate because I simply can’t be sure where the water is coming from. It is interesting that — no matter how much water I vacuum out — the water level of about 2 cm (0.8 inches) always reestablishes itself. This would suggest groundwater, but the drainage chamber is completely dry, not even damp. No movement on the main water meter, no pressure drop in the heating circuit, no dye found in the wastewater pipes.
Since I just built the house, I’m currently not in a strong financial position. Because the shell contractor went bankrupt, all costs are falling on me.
I would like to hear your ideas and, based on them, start investigating the cause.
At the moment, there is no suspicion that could narrow down the cause, which is why I don’t want to hire a leak detection company. In 2016, they couldn’t find anything either.
I hope you have suggestions or experiences to share on what I could pay attention to in order to find the leak and what is most likely causing it.
Thank you very much in advance for your answers.
Best regards
I’m posting here because I’m quite desperate and can’t find a solution to my problem on my own.
Background:
In 2015, I had a house built. I managed the construction myself and hired all the tradespeople directly. Meanwhile, the shell construction company no longer exists — they went bankrupt.
The house has a basement about 2 meters (6.6 feet) below ground level, with approximately 1 meter (3.3 feet) of it above ground.
The slab was poured in one piece. Afterwards, precast wall elements were installed — a “white tank” waterproofing method.
At the time of construction, there was groundwater in the excavation, about 10–20 cm (4–8 inches) high, so still below the slab.
The joints between the precast elements were sealed with bitumen. Metal sheets were installed between the wall and the footing, and in-situ concrete was poured into the precast elements.
About a year after completion, in spring 2016, the interior wall paint peeled off along a horizontal line approximately 20–30 cm (8–12 inches) high and blistered. I hired a company to investigate the problem, but nothing was found. They broke two tiles and checked down to the slab. The slab was slightly damp, but that was all; no cause was found.
Now, nearly two years later, the exact same blisters have appeared on the same wall, and plaster on an exterior wall is wet up to about 1 meter (3.3 feet) high.
I then removed a tile in another spot and broke up the screed down to the slab. There I found about 2 cm (0.8 inches) of standing water. I first removed this water with a wet vacuum cleaner, but this makes no difference, as the water level of about 2 cm (0.8 inches) always returns.
To investigate the cause, I did the following:
1. There is a drainage system around the house with an access chamber that can be opened at ground level. I opened it to check the groundwater level (the drainage is below the slab level) — completely dry, no water at all. However, I have to mention the chamber is located on the opposite side of the house, not where the wall is wet.
Question: Could it be that the groundwater level is higher on the other side of the house? The house is not located on a slope or anything similar.
2. I poured colored dye into the wastewater pipes to see if there is a problem there, then watched the spot in the house where I see the water (the opening). Nothing appeared.
3. I checked the main water meter; it shows only the smallest flow rates, completely still.
4. The basement is heated with underfloor heating. The heating circuit maintains a constant pressure of about 2 bar (29 psi) with no changes.
I’m desperate because I simply can’t be sure where the water is coming from. It is interesting that — no matter how much water I vacuum out — the water level of about 2 cm (0.8 inches) always reestablishes itself. This would suggest groundwater, but the drainage chamber is completely dry, not even damp. No movement on the main water meter, no pressure drop in the heating circuit, no dye found in the wastewater pipes.
Since I just built the house, I’m currently not in a strong financial position. Because the shell contractor went bankrupt, all costs are falling on me.
I would like to hear your ideas and, based on them, start investigating the cause.
At the moment, there is no suspicion that could narrow down the cause, which is why I don’t want to hire a leak detection company. In 2016, they couldn’t find anything either.
I hope you have suggestions or experiences to share on what I could pay attention to in order to find the leak and what is most likely causing it.
Thank you very much in advance for your answers.
Best regards
ibo85 schrieb:
At the time, there was groundwater in the excavation pit about 10-20 cm (4-8 inches) high, so still below the slab.
.I don’t understand that. Why is the groundwater 20 cm (8 inches) below the slab?
Best regards,
Sabine
Maria16 schrieb:
Can you follow up with the leak detection company from back then regarding their warranty? I mean, ask if they can search again at no extra cost? I don’t think so. I had signed the report prepared by the company at that time.
It’s not about small costs up to 500 euros. If I could be 100% sure the leak would be found, I would be willing to pay 1000–1500 euros. But that’s not the case.
Similar topics