New single-family house in southern Germany

I think we tend to belong to the second type. We kind of stumbled into building. At this point, I also have to say that in hindsight I’m quite glad that in the first targeted new development area everything was already taken, so we searched for plots for a while and our area is only now being developed. If it had worked out right at the beginning, we would certainly have fallen into many more traps or simply taken what was in the catalog and only questioned it after moving in. Especially regarding realistic cost estimation and ancillary construction costs, that should not be underestimated either ;)

If this is your only problem, it can be solved.....time.....searching.....asking.....as I said, our result no longer has much to do with the original idea and we are now exactly looking forward to that.
Always start over mentally at zero, there are many ways to Rome; here mostly the mainstream is discussed and often in my opinion too technology-oriented, but there are also many other things next to it, which are also justified. Everyone should find out for themselves.

I don’t know if this is our only problem. It certainly has further implications if you leave out the basement, like the need to create storage space, for example in the attic. Currently, the house tends to be quite large and whether the large attic plus possibly an extension for the technical room really pays off compared to the basement... doubts are coming to me again.

There are definitely further implications when you leave out the basement, such as the need to create storage space, for example in the attic. Currently, the house tends to become quite large, and whether the large attic plus possibly an extension for the technical room really pays off compared to the basement ... I am currently having doubts again.

Start first with your living spaces. So: create a room program. The rest will develop.

and the study on the ground floor, mostly in the northwest corner. Although the builder’s planner of the local general contractor rather has it in the east-southeast corner

I really cannot comprehend such corset statements, for example.

Currently, the house tends to become quite large, and whether the large attic plus possibly an extension for the technical room really pay off compared to the basement in the end... I am currently having doubts about that again.

But you can't build a house out of doubts. An above-ground technical room does not necessarily have to extend the ground floor. We have already discussed and solved similar issues here - with :

The space requirements are actually quite clear. Living kitchen on the ground floor. Preferred is a layout that somewhat separates the kitchen from the living room, so a bit around the corner. These layouts with a kitchen island in the middle of the open plan do not quite appeal to us. In addition, definitely the office. That combined with an L-shaped open plan results either in the open plan over south and the slightly recessed kitchen in the east, then the office in the west. Or alternatively kitchen and dining room over west on the long side of the L and the living room on the short side. Then the office in southeast/ESE. Definitely excluded is the office in the northeast as that will be the less desirable corner of the plot. Additionally a WC, probably with shower, possibly the technical room and optionally a storage room/pantry, can be small too. Upstairs main bathroom, master bedroom, children’s room and a second office/guest room. What is still missing in this program are the storage rooms for things that are not used so often: tent, skis, the living room armchair that is not needed at the moment but is too good to throw away, etc., so either a basement or a large attic.
I know you can’t build a house on doubts. But of course it is difficult to make decisions when the costs are not reasonably known. If money didn’t matter or the options didn’t make a difference, I would definitely build the basement. Two things essentially hold me back from that: The issue with arsenic and the horror stories based on that from the forum about costs for excavation. And that back when KfW40+ was quite important we realized that it does not fit in our budget with a basement, regardless of arsenic. Since 40+ is not really an issue anymore, I am wondering whether the compensatory measures for the missing basement might ultimately be more expensive than the basement... I will take a look at the thread soon. But just from the title it is clear that we wouldn’t get that done with one of the prefab builders ;)

I'm wondering whether the compensatory measures for the missing basement might end up being more expensive than the basement itself...

Do you know my basement formula?

I'll take a look at the thread now. But already from the title it's clear that we wouldn't manage that with any of the prefab builders

Not me - enlighten me :)

I do not know the Keller formula.

Necessary changes for the technical room in the attic: proper stairs to the attic, proper conversion of the attic, complete change of the installations. Since the houses from the catalog with the wish list are already at the limit of the budget, the changes will certainly exceed it. I think that only works with a company that does not charge a lot of money for sales on each house.