Construction costs 2500 €/m2 realistic solid construction completely

It is probably referring to the ancillary purchase costs, then it fits.

I can't get a decent central ventilation system for 9k, can I?

Well, I can only speak for myself here.
We are paying 8k€ net for a Vallox with FRG + WRG.. A bit over 3k€ more than a decentralized one would have cost us.
Of course, it can vary from installer to installer. But it probably shouldn't cost more than 5k€. After all, it's just one device plus pipes..
You could even lay the pipe yourself on the ceiling. That will save you something too.

? That's nonsense.

Well, it would be new to me that ancillary construction costs have a "value-increasing" influence on the loan valuation... So why should that be nonsense then?

I consider it extremely value-enhancing to have electricity and running water in the house...

just found on Gevestor.de:

Construction costs: €200,000
+ Additional construction costs: €23,000
+ Outdoor facilities: €8,000
= estimated production costs: €231,000
– Safety deduction (15%): €11,550
= Construction value: €219,450
+ Land value (=purchase price of the plot): €150,000
= Mortgage lending value: €369,450


However, this will vary somewhat from bank to bank as to which deductions and additional construction costs are accepted. The accompanying building surveyor, for example, was not included in our calculations.

So it would be new to me that incidental construction costs have a "value-increasing" effect on the lending value...So why should that be nonsense?

It depends on the bank. Many just apply a discount, which is significantly smaller than the total incidental construction costs.

However, there are also banks that are more exacting, or on the other hand include incidental construction costs completely in the lending value.

But it doesn't matter anyway. In the end, what counts is how much the external capital costs overall.