House raised higher than approved; additional costs after approval?

I wouldn't be alarmed about that right now either. That is the responsibility of the client, which you are not. What I would be careful about, however, is if the contractor changes the ceiling heights / roof pitch etc. and thereby no longer fulfills the contract. Ideally, one gets along well and discusses possible solutions together. You can also agree right away if the error should justify a reduction. Perhaps simply new plans at the authority will also suffice.

Everything from 2m counts as a mountain in SH?

Several houses can also be operated through several GmbHs; if one of them goes bankrupt because of something like that, the others continue to operate.

Whoever has enough capital to set up a second GmbH first separates their BT and GU activities. Project companies also exist, but rather not for individual single-family houses.

What does it mean to equip a GmbH? The minimum would be a contribution of €12,500. It would then be a pure management entity and everything would be forwarded to other GmbHs by order.

What does it mean to equip a GmbH? The minimum would be the contribution of €12,500.

The other half of the contribution would also have to be made first before it could be withdrawn again - and capital in the manner of a "daily admission" would bring nothing creditworthiness-wise and would be on the edge of an own goal in terms of solvency.

So we were able to speak with the head of the company, he is willing to meet with us on the construction site next week. We will clarify both questions about the house itself and address the missing building permit for the property securing. Neither we nor the buyers of the other semi-detached house are willing to bear the costs here, as we do not want to be responsible for the mistakes of the BT. We will address this and see how the reaction turns out.