The floor slab for the sewage pipes was poured incorrectly!

Unfortunately, I commissioned those separately. The foundation slab builder naturally also poured them in directly instead of keeping the pipes flexible and pouring later. The house builder has said little about it so far because the foundation slab is a self-service task. I will schedule appointments next week to clarify this.

And which expert checks the situation?

It happened as it had to! No expert so far in the construction project

It happened as it had to! No expert on the construction project so far

Ouch. Because of the importance of OKKD / foundation slab as an interface (and the fact that you can do a poorer "compensation botch" with prefabricated houses), I would always want to place that within the warranty scope of the house builder. And if that's not possible, then absolutely definitely put a very sharp expert on the construction site.

Is it possible to have [Hauff Anschlusstrichter] installed afterwards? I am aware that chiseling will be necessary, but that would have to be done anyway!

Can they still be installed or is it basically no longer feasible or very difficult?