Expert for settlement cracks (Lüneburg area) wanted

Hello,
can someone recommend a good expert?

The situation is as follows. Three years ago, we bought a semi-basement house from 1966 and replastered all the interior walls. Half a year later, a new building was constructed next to us, and at a distance of about 5-8 meters (our house is positioned diagonally to the property boundary), a 2.5m deep pit was excavated to create a basement and lower garden. The neighboring property is therefore significantly lower.

During the construction phase, steel beams were driven 8m deep and wooden beams were layered in between. It was quite something how everything vibrated when the steel beams were hammered in – although in pre-drilled holes, it was still annoying. After the beams were removed, it took several months until L-supports were built at the edge.

Now we have the problem that cracks have appeared on the two interior walls of the non-basement side of the house (the basement is on the side towards the neighboring property). The cracks run diagonally upward from floor level at the exterior wall towards the center of the house (along the brick joints).

We first noticed that cracks had appeared over a year ago. The cracks are very narrow, in some places no more than 2 mm, but clearly visible. It seems to me as if the house has subsided somewhat in the middle.

That a 40-year-old house suddenly settles anew is a bit strange, and therefore a causal connection to the new construction next door suggests itself to me.

However, I would like to have this assessed by an expert.

Thank you very much for your help.

I can already tell you in advance what the expert or a construction lawyer will say: If you have not documented the house in a legally binding manner before the construction work, then unfortunately you will have no real chance of proving the causal connection in such a way that you can assert claims.

Artrium Architekten in 21423 Winsen/Luhe. Mr. Ulrich S. seems very committed to me.

Is that really the case?
I know a case, admittedly from Sweden, where a lot of blasting is done.

In my colleague's case, the obligatory vibration sensor on the house was forgotten, so the company carrying out the blasting could not prove that the vibrations were within the permissible range.
His damages were therefore paid for.

It might be different here in good old Germany. But I would find that strange, because how am I supposed to know that the neighbor will show up tomorrow with a steam ram and hammer 10m long steel piles into the ground, and then quickly bring the sworn expert for an inspection of my house? The damage could already have occurred on the first day...

If I play soccer in my garden and the ball flies into the neighbor's window, I also can’t say
"Well, tough luck, you should have built a better fence, you know I play soccer..."
It is my responsibility that things I do on my property only cause damage there and do not affect the neighbors?

Normally, the process is as follows: as soon as one becomes aware of the commencement of construction activities, one submits their concerns in writing to the client and requests a corresponding expert report. The costs are usually borne by the client. If the client refuses, one should consult a specialist lawyer who can, in extreme cases, also apply for a construction stop in court.

Hmm, honestly that seems quite unrealistic to me. For me, the civil engineering took 2 days, including driving the piles maybe about a week? By the time the letter has even reached the client and, above all, been read, the steel piles are already sunk into the ground... Has this already been decided by courts, is there a case number as an example?