Ensure compliance with soundproofing requirements when accepting a condominium unit

Have the sound insulation certificate according to DIN 4109 provided to you – it is one of the documents that must be submitted with the building application. Then you check whether construction was carried out according to the specifications and plans. It’s quite simple – for example, during acceptance, knock open walls and check ;) . Of course, that doesn’t work. It should have been done during construction. Therefore, you can only rely on the documents and see if there are any implausibilities.

Since the implementation/realization during the construction phase can only be monitored at the discretion of the developer, it seems to be "the rule" that as a buyer you stand at the acceptance without detailed knowledge. Otherwise, monitoring/inspection for future owners would be somehow regulated by law or enforceable. Since this is not the case, it seems to me that my post #2 would be an alternative – again only feasible at the developer’s discretion. Are there any further intermediate steps before a complaint after noise disturbances have occurred? Background: I now KNOW of sound insulation problems in a sister house of the developer.

Are there further intermediate steps before filing a complaint after noise disturbances have occurred?

No. You can only report a defect once you have discovered it – or in your case "heard" it.

Since the implementation/realization can only be monitored at the builder's discretion during the construction phase, it seems to be "the rule" that as a buyer you stand at the acceptance without detailed knowledge.

Yep. You buy a finished product and do not build it yourself. When buying a car, you also don’t go to the factory to check whether diesel shutdown devices are really not installed or whether the wiring harnesses have been laid correctly. Complaints only after delivery of the finished product.

No. You can only report a defect once you have discovered it - or in your case "heard" it.

Yep. You buy a finished product and don’t build it yourself. When buying a car, you don’t go to the factory to check whether there are really no shutdown devices installed in the diesel or whether the wiring harnesses were laid correctly. Complaints only after handing over the finished product.

Good comparison, thanks for that. I think I’ll leave it at that. Just wanted to see if I have any leverage before the reversal of the burden of proof. Doesn’t seem so. Let’s see if I even have a problem now that I already know I have no solution o_O;)