Construction of a new single-family house with a basement and exterior basement access

Wasn't there something about a dam in South America connected to TÜV Süd?

Turn to an engineering firm specialized in construction supervision, do not skimp on the expertise of a surveyor.

Have your vehicles inspected by TÜV and the house construction by a civil engineer or similar. That does not necessarily mean that all TÜV inspectors are career changers from evening school, but the proportion of such is high there. And that is why construction companies sometimes only take the TÜV experts semi-seriously.

we are planning a new building with a general contractor.

Until today, you probably mean. Because tomorrow you will pull the plug, hopefully nothing has been signed yet (otherwise you should quickly see a lawyer beforehand). The reality TV fees will not cover the expensive fun, 1. the debt service for the construction wreck, 2. the rent for your replacement accommodation, and 3. the housing of the tenant. A hopefully-maybe-WU basement chosen by the subcontractor ... I have no further questions. Run away as fast as you can!