Roof interior insulation incorrectly executed - major damage caused

But I stick to my point - applying for an expert for every job is neither necessary nor common. It would be even worse if I not only had to pay the high craftsman costs but also expert fees to supervise the master company. By the way, the invoice says "Master company for acoustics and drywall construction".

I see it the same way. Experts don’t exactly grow on trees. We tried to find an expert for a problem with masonry moisture. No chance. We then tried to inform ourselves, which is worse in the case of old buildings than theological discussions. Lots of matters of belief and everyone is an expert, while calling others criminals and idiots. We then simply had to trust and document.

Yes, that's true. You have to be glad to find a craftsman, let alone more specialists. In 2017, it was even worse than it is now. Tomorrow I have an initial consultation with the specialist lawyer for construction law.

The lawyer says one can argue with fraud/intent, but the prospects for this are not certain. We should first send a defect notification and set a deadline for remedying the defect, and if that expires, request an expert and file a lawsuit - if we want to. He said the prospects would have been very good if the defect had been noticed within the first 5 years. But of course, they are over, we knew that. We should in any case make the defect notification with a deadline because this could be important in a later trial. We will now do that. Whether we will proceed further, I don't know. We still need to assess the financial risk for ourselves.