How to decouple border cultivation (next to my house)?

Hello,
my neighbor is building an extension directly adjoining my house.
Because he is making a deeper basement than mine, he has already (without asking me) simply underpinned my house with concrete.
For this purpose, my house was undermined and concrete was poured directly under the floor slab (in direct contact with my slab).

Afterwards, the neighbor had his approximately 30-40 cm thick floor slab constructed and poured it directly against the concrete of the underpinning (without decoupling).
When his basement walls were poured (white tank), a layer of Styrodur boards (approx. 12 cm) was installed between the underpinning and my basement wall. The basement wall concrete was then poured directly from his side against these Styrodur boards. This basement wall adjoining my house was also made thicker than usual (it is approx. 30-40 cm thick). Due to the fluidly poured concrete, considerable pressure must have been exerted on the Styrodur boards and thus on my basement wall. And these Styrodur boards were certainly pressed very firmly against my basement wall.

Now my question is whether this was technically correct and whether his house is properly decoupled from mine according to engineering standards?
Since then, I hear every drilling, every hammer blow, etc. that they perform on his new building extremely loudly in my house. Everything vibrates along.
Shouldn't a "rubber layer" be installed there?
I have seen at other new buildings that even the floor slabs in a duplex were separated by a black layer.

Since his floor slab is virtually firmly connected to my house (through the underpinning), it seems that everything is transmitted here. In addition, Styrodur seems more like a resonator than a sound absorber.

What is your assessment of this?

Thank you very much

Johann

Sometimes went over and talked?

went over and talked?

Of course. But the workers' answer was that the builder has forbidden any communication with the neighbors and that the builder himself only rents out the apartment building (which he later rents out remotely). He is not reachable for the residents. Therefore, we unfortunately receive no information from this side.

Well, if that really is the case (construction workers also talk a lot of nonsense) you just have to look inside yourself and ask what you want. Stress? Then it's not hard to enforce a construction stop, if only because of the unauthorized underpinning work. It will cost you a lot of money and nerves. Or no stress, then just let it run. In the end, you can still sue the builder for damages. If he hasn't created a status documentation, you can sue him for any damage to your house without any problems, even if it's the Rembrandt that fell off the wall during the construction work.

I would be glad if I could simply get an answer/assessment on the technical aspect of the topic of decoupling (as I asked). The other things have already cost us enough nerves, stress, and time – it would be too much to describe them here (and probably boring for most). I also know with the injunction that he has to pay me damages and a reduction in value. However, if I do not act immediately regarding the decoupling, he will create further facts through his ongoing construction, and afterwards, I will no longer be able to do anything, as a judge will certainly not order a demolition.

If I do not act immediately with the decoupling, he creates further facts through his ongoing construction and afterwards I can no longer do anything, as a judge will certainly not order a demolition.

Then you are in the wrong place here in the LAYMANForum and should urgently talk to an expert. Only there will you get certainty.