The plan was/is to contract the basement ourselves. We found a basement builder who has worked several times with our main contractor (GU), but is not in such a close contractual relationship with him that he is not allowed to accept orders from the GU’s customers anymore. The basement builder’s offer was then significantly better, as we get a white tank for almost exactly the same price compared to just a normal black tank through the GU. We are building on a slope and the soil is mostly clay, so temporary water accumulation is to be expected during rain/heavy rain. I find the white tank much more appealing than a black tank with drainage, which has to be maintained regularly. For the same price, it was an easy decision for us. Since the basement builder knows the GU, the processes, site managers, etc. are also familiar, so I don’t see any real problems. The plans for the basement are made by the GU anyway in the factory planning.