Hello everyone,
Our house has a basement constructed with a waterproof concrete shell ("white tank"). The groundwater level on our property is very high, so this was necessary. We are working with a general contractor (GC).
After completing the basement, we hired an expert to evaluate the construction execution. In their report, the expert criticized that the perimeter insulation was only partially fastened with mechanical fixings, whereas according to the applicable DIN standards, it must be secured continuously.
We immediately forwarded the report to our GC and repeatedly requested that the insulation be properly fastened. However, our GC completely ignored this and instead backfilled the area.
This raises the following questions for me:
- What impacts and consequences could result from the missing mechanical fixings?
- How extensive is the work needed to add these fastenings later on? Is it even possible? Secant piles were necessary during the basement construction to keep the groundwater out, and those are now obviously no longer in place.
- What is the best way to handle this situation with our GC? Established standards were ignored, and we pointed out the defect in a timely manner (before backfilling was done).
Thank you for your experiences and advice.
Our house has a basement constructed with a waterproof concrete shell ("white tank"). The groundwater level on our property is very high, so this was necessary. We are working with a general contractor (GC).
After completing the basement, we hired an expert to evaluate the construction execution. In their report, the expert criticized that the perimeter insulation was only partially fastened with mechanical fixings, whereas according to the applicable DIN standards, it must be secured continuously.
We immediately forwarded the report to our GC and repeatedly requested that the insulation be properly fastened. However, our GC completely ignored this and instead backfilled the area.
This raises the following questions for me:
- What impacts and consequences could result from the missing mechanical fixings?
- How extensive is the work needed to add these fastenings later on? Is it even possible? Secant piles were necessary during the basement construction to keep the groundwater out, and those are now obviously no longer in place.
- What is the best way to handle this situation with our GC? Established standards were ignored, and we pointed out the defect in a timely manner (before backfilling was done).
Thank you for your experiences and advice.
Wouldn't it be completely pointless to drill holes into a waterproof membrane with anchors? What could possibly shift there? Standards like DIN aside, that can’t be changed now and it’s not a big deal, but you should immediately discuss the way this was handled with your main contractor. In situations like this, you meet on-site for a discussion or have a phone call—you don’t just do things without consulting.
The anchor holes are only a few centimeters deep and do not have any impact. Otherwise, you wouldn’t be allowed to drill from the inside either. A waterproof concrete shell (“white tank”) is 20cm (8 inches) or thicker; from 12cm (5 inches) thickness, it is considered water- and diffusion-tight (experts debate diffusion resistance—some argue it is never fully diffusion-tight, but only sealed by the bitumen barrier layer. That’s why the DIN standard still recommends a barrier for higher performance requirements. However, this has recently been disproven by tests).
Therefore, holes, anchors, etc., are not a problem.
When gluing, the styrofoam can shear off because it is only fixed superficially. Due to settlement or incorrect backfilling, it can tear away. Using anchors prevents this.
Therefore, holes, anchors, etc., are not a problem.
When gluing, the styrofoam can shear off because it is only fixed superficially. Due to settlement or incorrect backfilling, it can tear away. Using anchors prevents this.
Lumpi_LE schrieb:
It’s not written there.
Can you tell me according to which one?
I still maintain that this simply isn’t true. So what is true then?Lumpi_LE schrieb:
You should add that this is just your opinion. Standard regulations and dew point are different, after all...No, this is not my opinion, or what exactly are you referring to? Much of this is also manufacturer specifications.Snowy36 schrieb:
what is correct then?I only know that, contrary to the original poster's statement, none of the mentioned standards regulate this. @Bookstar believes it must be done to prevent collapse in case of improper backfilling or settling.
He is probably not wrong, but generally, it is assumed that the work is done properly and no excessive settling occurs; otherwise, the regulations would be endless.
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