Retaining wall for the retaining wall!? Do you have any ideas?

Where are we supposed to know how far away that is?

@all In picture 2, the situation is shown from above and labeled. Our house is approximately 4m away from the neighbor's retaining wall in total.

Or am I misunderstanding you?

Exactly, except that with us sections 2 and 3 remained and only the 4th was dug up again.

With us, the section that remained standing was also larger than in the posted photo.

Let's continue on the L-block side on the left, now we have a solution for the wall. But how do you see it with the roots, if we cut them off, they will eventually die. Couldn't it really happen that the L-blocks don't tip forward, but rather sink downwards, right?

Can you say something more about the roots? Do you also see it as critical?

We had no roots.

You can't decide that alone either. Look at what is supported by the wall. As I wrote above, civil engineers, architects, experts, geologists, and structural engineers were involved with us. There was no house just behind the wall on filled soil. With us, a naturally grown, undeveloped slope was retained by the wall.

A distance of 4 meters is not much when you consider that an excavator has to be positioned and work there. The excavation also needs workspace in front. In our case, the foundation was poured and then built up with masonry, as the structural engineer wanted. That means a worker also had to be able to move sufficiently in the pit, and equipment also had to be able to approach. If you are excavating for a basement, there is no longer 4m distance to the wall either, because workspace is also needed there and the pit has to be battered. I don’t see the problem with the roots in the approach of underpinning. But even there, the structural engineer will tell you the best way to proceed. Of course, he cannot decide that from his desk; at critical points he came out to us and gave precise instructions on how to proceed further.

I would try to find a solution without having to touch the retaining wall. If I remember our prices from 18 correctly, you will be spending a small five-figure amount on the underpinning.