2.25m below street level - Cost estimation

Groundwater is 10 meters below the street ... or did I misunderstand that?

Why soil surveys? If you're really filling in 2m of sand and gravel, the deeper subsoil probably won't matter much, I assume. How high above street level are you allowed to build?

TH 7.0 - FH 10.5 measured at the street, so "normally" high. Yes, the pouring out is part of my concern, see first post.

I would clarify with the building authority at what level they consider the "terrain surface edge" in terms of reference measurements. Sometimes, the textual provisions of the development plans also specify where and how to fill or level certain areas.

So, the idea of "bringing my property up to street level with fill" does not necessarily have to be "correct." It’s better to ask one time too many.

We often have this issue here: building a garage on the boundary, it may be 3 m high, but from where is it measured. This becomes all the more hotly debated the more differently elevated the neighboring properties are. So coordination with the neighbors is also not a bad idea.

Just for orientation: Under our house, which is 15x15.5m, we had to take out one meter and then add a total of 2 meters of fill. In addition, there is the 100 sqm driveway, and the excavation went into the garden. We ended up at 25k. Are you the only ones sitting in the depression and the neighbors around are up? With such a strong level difference, I would almost build a basement. We were also advised to do so, but we absolutely did not want a basement. The area under the house and the driveway is filled with gravel. If allowed, RCL gravel (requires approval). The garden should have fill soil and on top of that a thick layer of topsoil.

Incidentally, a note on a "neighbor thread":