Responsibility of the architect in case of KfW interest and further matters

Mea culpa. Of course, cost calculation was meant.

It wasn’t meant to be as instructive as it might have sounded. Sorry

If you want to achieve the "turnaround": better now than never.

But what should that look like? In the case of a new build, you might possibly stop the construction and plan smaller again, but with an existing building? Whether the extension has 1 or 2 floors probably won’t make much difference, and with only 100m² of living space originally, it seems to me that it is pretty far up on the priority list.

Everything else on the list of measures, except for a few exceptions, are items that could only be controlled through quality, but for that I don’t need a cost calculation; I have to ask the contractor which variant will be cheaper.

I am definitely learning that nothing verbally agreed upon should be carried out without a price. For example, we mostly demolished a covered terrace ourselves, and regarding the floor, the architect said that it wouldn't hurt if the structural builder handled it. The bottom line: we paid 2231 euros plus VAT in labor costs and 490 euros in disposal costs just for that. It was labeled as "Skilled worker daily wage hours according to measurement." But this was never discussed again until the invoice. We did not agree to anything there, received no estimate, nothing.

Also, on Wednesday we were informed that the young architect had told the structural builder to remove some of the soil behind the extension since he was already there. We stopped that immediately by email after receiving the invoice.

Is it common to only learn the prices for such additional tasks on the invoice? Everything should be documented in writing, right? But in the end, he could claim all sorts of things were done... I also can’t imagine that removing the terrace took 46 hours. I mean, it was already gone on the second day when I was at the construction site.
For such an amount, I would have gladly done it myself.

But what is it supposed to look like?

Just the omission of the 9m double prefab garage will probably relieve the budget by 20,000€. Completely without any loss of living quality.
Next comes prioritization: Do I really need all bathrooms/rooms fully finished now, or can the completion of this not immediately needed living space be postponed to a later date with possible own work? A paved driveway/terrace/path to the door is of course nice for moving in. But some people (including us) have entered their home for years over Jura gravel, not over a step, but over a Euro pallet. The driveway is still kept in timeless Jura gravel look.
"Unnecessary, but nice" things like spotlights etc. have already been mentioned. And then you can talk about own work and quality. All of this, of course, only if the living conditions of the OP allow it.

Yes, we really need to think about that. We have been looking forward to the garage for 10 years, it would hurt a lot. We have also considered whether to forego the paving work for the time being.

: Read post #49

But where do you see the benefit of a cost calculation in this context? I can only repeat myself and speak from my own painful experience: Such a construction really takes a toll and you will have to deal again and again with the most diverse parties involved. I would divide my energy and only intervene where there is something to gain for me.

In this case, step on the civil engineer's toes and have him explain how he arrives at 96m³ and why the disposal costs him such astronomically high sums.

I don’t think it is productive to upset the architect at such an early stage for basically an obsolete piece of paper.

We have been looking forward to the garage for 10 years, that would hurt a lot

For that money, you can also afford cars with parking heaters for the rest of your life.