Evaluation floor plan approx. 145 sqm single-family house basement/ground floor/upper floor

Why do you think the basement is significantly cheaper than the above-ground living space? Your basement is within the thermal envelope and partially includes finished living space. How should the utility room be equipped? It needs underfloor heating as well. The room height will certainly be normal. Do you think slightly cheaper tiles and small/no windows bring such savings? You will have additional costs, for example, for waterproofing compared to above-ground living space. I would estimate the basement at 80k plus the garage costs

And how do the 50k of own work break down? Do you have trades within the family?

See #42, in the family there is at least a carpenter (interior finishing) and an electrical master (electrics up to acceptance). I hope that we can save the most during the shell construction through the builders' own help. We will work with a "freelance" mason who has also built most of the other houses in the new development.

Regarding the basement: I've often heard this guideline here in the forum. But, as said, a professional will soon write something together about the costs.

I would roughly arrange it like this. How exactly the interceptions will be has to be seen in detail. But I also believe that the 400K will probably not be enough there. Lately, I hardly see any houses under 600K (including incidental construction costs, about 160m2) on flat plots.

with a 20% slope towards the west, it's not that simple. The terrace would have to be massively filled up. A carport or garage under the terrace could help.

I would build more with the slope rather than putting a basement underneath.

If it would dramatically reduce construction costs, one could also consider omitting the office in the basement. For now, there are only two of us and two empty rooms, which are supposed to become children's rooms. If there are then two children, it might be possible to convert the attic into a small office. Storage space would then be more available again in the basement. It may seem a bit silly to some, but we really have to keep costs as much as possible within limits.

You have to build with the slope. Building a usable basement underneath is not cost-efficient. It is more expensive storage.

I would roughly arrange it like this. How exactly the interceptions will be, you have to see in detail. But I also believe that the 400T will rather not be enough. Recently, I hardly see any houses under 600T (including incidental building costs, about 160m2) on flat plots. [ATTACH alt="bewertung-grundriss-ca-145-qm-efh-kelleregog-533784-1.jpg"]66167[/ATTACH]

This makes sense and was already recommended here several times yesterday. I don't understand at all why the terrace is oriented towards the neighbors in the east… I mean the main terrace and no one even addresses it?! Could it be that the living room is given too much importance regarding the evening sun?

The first cost estimate from the architect was 440k at the end of last year

You should always keep in mind that architects misjudge by at least 1%, more often by 20%, since they calculate with the enclosed space. Comparisons that have been read here in the forum over years confirm that the living AREA plays more of a role in cost estimation in the single-family house sector. But you have the craftsman in the family who will pull it off :)