Neighbor wants to build a semi-detached house with an offset

Well, it's a matter of perspective, we have looked at numerous 40-year-old houses over the last 2-3 years, none of which were, and all of them were moldy at the corners.

Yes, it will just become much more expensive for both, and at the back our corner wall would then probably need a retaining wall or a 2m deep strip foundation. At that spot it is the deepest, down to road level, topsoil removed about 1.5m plus or minus.

So, you want to build without a basement (as first-timers), even though in your case that means the luxury of ignoring the terrain and your house corner requires underpinning. Whether he wants to build with or without a basement, you don’t know, but you consider his intended offset as worsening the situation of your suspended floor slab corner?
It seems to me there is more at stake here than just his not being forthcoming about his real motivation and you not asking about it either. Who is burying their head deeper in the sand is hard for outsiders to “measure” – the main thing is you regard your kitchen planning as final, even though all questions are still open.
If I become king of Germany, I will ban the uncoordinated construction of semi-detached houses and introduce mandatory intelligence tests for the builders on both border sides.

All plots must be filled equally ;) Even their corners. He is not building a basement because prices start at 100k in this country at the moment, we asked.

He is not building a basement because prices start from 100k here at the moment, we asked.

Once again someone who hasn’t read the 11ant basement rule: a basement does not cost its price, but the difference between its price and that of the alternative terrain modifications. And he probably hasn’t taken the costs of your underpinning into account either. I stick to my point: you both should reconsider the plans and then lay the foundations at the same time.

Simple basement then results in a difference of 60-70k

Simple basement then amounts to a difference of 60-70k

And the rooms that can be done there have not yet been deducted.