Unauthorized high-quality work - additional costs

But not the client either. If the general contractor received knowledge of the Bedengutachten after the planning and acted independently, it is strange but professionally correct.

Better than a defective building. And if you don't pay, he won't build. And won't build and won't build.

Have a factual conversation with him.

It is different if he submitted the offer with knowledge of the report. Then he miscalculated.

And if you don't pay, he won't build.

A changed version, without notification, is not to be compensated - unless the client gives his approval afterwards.

If the general contractor does not build, you can still apply pressure through a claim for damages. I am also in favor of communication and of course it is more pleasant for all parties involved if you always part on a handshake. But many clients let themselves be forced into outrageous prices beforehand and then led like lambs to the slaughter during construction.

Yes, possible. Maybe also a misunderstanding. And if the general contractor [GU] built properly, the client would have had to have it done. No general contractor [GU] intentionally builds without proper warranty. Especially not if the client is aware of it.

And you can certainly sue for your rights. Especially when you already have a double burden because of the construction and money in abundance.
And the general contractor [GU] knows that.. That's where the problem lies. Unfortunately!

You still have the 3-5% security retention. When the final invoices arrive, the house is finished and you no longer have the risk that the [GU] will stop building. Worst case is a legal dispute. Whether you want that is another matter.

a legal dispute in this case would probably have relatively good chances, since there is no contract regarding the additional costs. nevertheless, it makes more sense to talk to the GU and settle it that way. as already said, for example with a drastically reduced invoice for the costs that were actually incurred (maybe 1000€ out of 5000€)...

How did it turn out??