Deficiencies in the new construction. Dispute over the amount of withholdings.

I could also insist that the copper pipes - as contractually agreed - be installed, right? It is my right to receive what I have paid for or what was agreed upon. Or am I mistaken?

Then you can: insist that everything be changed. If you understandably don’t want that, then there is no financial compensation for what it WOULD have cost. Instead, there is a small flat rate, which apparently (I am not an expert in this regard) is meant to be a comparable compensation.

According to my friend who is a plumber and supply technician, the costs for the replacement would be well over €10,000. Not to mention the consequential costs (the bathroom and guest WC would have to be retiled, the house would not be habitable during that time as there would be no hot water, so the developer would have to provide alternative accommodation, ...) The consequential costs are also his responsibility. As already written, this affects 3 parties and we agreed on this amount together. And no, I am not a teacher and it’s not about my ego ;). It’s about facts, such as that according to literature copper is less prone to corrosion than steel. If the consequence is that I have to replace the pipes 20 years earlier because of this, then I suffer a significant damage here that is not covered by €500.

No, you are mistaken there. Settlement payments are not payments made in the amount of the “repair”. On the contrary. It is the compensation for the “disadvantage”. The disadvantage could be €1,000, that is paid, the repair could mean €100,000. You now want the €100,000 instead of the compensation payment of €1,000. That’s not how it works.

You first have to find and fix 70 defects, chapeau to the developer for having fixed most of them.

Well, I tend to think: what exactly is being complained about so that 70 defects - these are legally valid defects - are claimed. If it were 5, 10, or even 20 defects (there are quite a few trades involved)… but 70! … what exactly is being designated as a “defect”?! Without an expert I am rather skeptical—over the years I have read far too much nonsense here. Whoever shies away from an expert and his costs must also expect that he will not receive what is due to him in the case of apparently serious defects. What is the problem that the expert acquaintance does not confirm the defects in black and white?

So, I’m more in the mindset: what exactly is being criticized here, that 70 defects – these are legally relevant defects – are being pointed out. If it were 5, 10, or even 20 defects (there are quite a few trades involved)… but 70!… what exactly is being called a “defect”?!
Without an expert I am rather skeptical – over the years I have read too much nonsense here.

The 70 defects were criticized by our expert and also accepted by the developer’s expert (keyword undisputed defects). Many defects were not fixed and ultimately only compensated financially to a small extent (as I wrote above). There were sometimes bizarre issues, like in the guest WC, for example, where the door hit the sink. Or they forgot to install a water softening system. Walls were not plastered, etc. It’s understandable that trust is lost in such cases, isn’t it?

Then you can insist that everything be changed.
If you understandably don’t want that, then there is no financial compensation that would have covered what it would HAVE cost. Instead, there is a small flat rate, which apparently (I am not an expert in this) is considered a comparable cost compensation.

Well… that would have meant that we, along with our two children, could not have lived in the house for a longer period. We would have had to move into a holiday apartment or similar. Besides that, the entire supply shaft from the basement to the roof would have had to be opened up, which would have meant that the bathrooms and guest WC would have to be retiled, since the supply shaft naturally runs through them as well. So an enormous effort, which the developer clearly said would be unreasonable and that I could not demand these works. So he was not willing to do so at all. We had no choice but to come to a financial agreement.

Update: I have consulted with my expert. He told me that the steel pipes are not a problem overall and gave me a sum on which we should agree. He also pointed out that I should find out whether the heating system was filled with water that meets certain standards (desalinated and demineralized water). He sent me the standard and I forwarded the inquiry to the developer.

In the meantime, we have agreed on replacement payments for all other defects, because I was ultimately fed up with the whole topic. Maybe that’s also the developer’s strategy to wear down the buyers. But I come out of this feeling that I have by far not received what I paid for and that the developer clearly came out as the winner here. So less service for almost the same money.

Thanks for your feedback and opinions.

I do not allow so many defects to occur with my general contractor in the first place. Although we also purchased [Bezugsfertig], I still inspect all trades and respond immediately to any discrepancies.

Has the OP already written that he was not allowed in. It was a developer. If the circumstances had allowed it, I simply would not have accepted it.

Now 6 pages have been discussed here, but we still don't know which steel pipes they are. If it is stainless steel, then the replacement is definitely disproportionate and as compensation there is the difference in material price plus a small compensation. There are even people here in the forum who want to replace all the pipes in 10-year-old houses, water, heating, and electricity.

What can you say. Take the money. The doors/windows won't be replaced anyway, you can fill in the Q2 plaster yourself (for 100 EUR per wall you could probably even have it brought up to Q3 by a professional company). And the steel pipes are not a big deal either. Since the circuit is airtight, basically nothing can corrode there. You can only insist on the contract. And then hope that the expert the court ultimately believes says that steel is not an adequate alternative and therefore it must be converted to copper. I consider the probability of that low, because steel is allowed to be used. Serious damage would have to be threatened for the conversion sum. If you want to take the legal route. Then do it. But it will take several years, outcome uncertain. Oh, and whoever loses pays the legal and court costs of both parties. Unless there are really defects where you face serious damage to the building structure in the long run. Like botched insulation, which then threatens mold or something like that.