How much additional cost according to the structural engineer's calculation?

no, that's not correct. they would have sealed our basement with bitumen coating and drainage

And what is the difference between "Bitumenanstrich" and "schwarzer Wanne"?

no, that's not correct. they would have sealed our basement with bitumen coating and drainage

I cannot reproduce it exactly but it would have been sealed. In addition, DEKRA inspects the construction with

I can't reproduce that exactly but it would have been sealed. In addition, DEKRA checks the construction with

A "Schwarze Wanne" (black tub) is the waterproofing made of bitumen thick coating, bitumen or plastic sheets. So what exactly did the general contractor want extra money for again in the mid five-figure range?

The term "Schwarze Wanne" refers to a waterproofing made from bitumen thick coating, bitumen, or plastic sheets. So what exactly did the general contractor want extra money for in the mid five-figure range?

According to the internet, a waterproof concrete cellar costs far more than 25,000 euros (plus 3,000 for static calculations). They charged the amount for the "normally" sealed cellar.

according to the internet, the WU concrete basement costs far more than 25,000 euros (plus 3,000 for static calculations). they charged the amount for the "normal" sealed basement

I meant wanting extra money for a black tank, if you already have a black tank in the original offer, according to your statement. I myself have a sealed :-D WU basement made of cast-in-place concrete

That doesn't help you at all, dear... you don't have enough financial reserves for this project, period end.