Build a terraced end house with an additional unit (GÜ) on your own

And what conclusion would you have drawn as a "cheap" building land seeker?

The building land is indeed "cheap," but due to the aforementioned issues (roof pitch, with basement, without basement, construction sequence), it is hardly reliably plannable and executable as an individual project in advance. The unknowns and dependencies are simply far too dominant here.

That seems to me to be the main inspiration for the communities, to rather cover their pipes than to bury them :-(

According to the site manager, this is due to the drainage situation - therefore it had to be built so high.

The building land is indeed "inexpensive", but due to the aforementioned issues (roof pitch, with basement, without basement, construction sequence) hardly reliably plannable and executable as a single project in advance. The unknowns and dependencies are simply much too dominant here.

It’s no different for us than when I build a semi-detached house – and in this case, I am even the first builder.

According to the site manager, this is due to the drainage situation - that's why it had to be built so high.

Once the height planning error is made, it must of course be carried through into branching streets :-(

So... today I commissioned the geotechnical report - on Monday they will start sampling directly and then it will take about two more weeks. After that, we will know the actual costs for the "jacking up" of the house - until then I am still waiting for an initial assessment from our general contractor that we requested.

Unfortunately, you can clearly tell in our region that currently very few people need to accept orders. I contacted at least five companies for the geotechnical report: either sky-high prices of over €2000 or the fine ladies and gentlemen wanted to drive to the construction site only when the road is finished. However, it is already gravelled and compacted, so that should actually not be a problem, since the earth movers are also driving around with their trucks and flatbeds there. In the end, I was fortunately able to find a company that now costs us about €1100 - and that, even though no boundary stones have been set yet. Our friendly construction manager from the development company made a sketch so that the surveyor drills correctly.

Yesterday we submitted our notification procedure - the development work will probably also be completed on time so that construction can start in October.

Today I had a conversation with our general contractor: after consulting with the structural engineer, he will probably have to make strip foundations with a total height of 2.40m. The additional costs including material for backfilling will, according to his estimate, be about €16,000-17,000. He can only give us an exact offer after the geotechnical report. However, we now have a reference point.

Of course, we will try to get material for backfilling from other construction sites that are building with a basement. However, they will probably throw their excavated material into the garden.

Of course, we will also have the basement issue recalculated with the new conditions.

You can't use the topsoil for backfilling anyway. I would buy the basement. It's practically already there. 2.40m strip foundations = ideal basement height. You can just leave it unfinished for now. Then you only pay for the stairs, the floor, and the most necessary load-bearing columns, right? Have a few empty conduits laid down... In case of sudden wealth, you'll be happy; otherwise, it's storage space for comparatively little money.