GU wishes construction supervision from DEKRA

I see it the same way. Was my post meant differently? I wanted to question the purpose of construction through architects. After all, you have the site manager on your side there and already compensate him for it.

correct, basically the architect is already your expert. however, he always works with the same companies, so he doesn't want to upset them. whether you need an expert yes/no is also always a question of how the construction company deals with defects and so on. you absolutely need an expert for: basements, especially with already existing high groundwater and special installations; and whenever something seems strange to you.

Even your own architect can make mistakes, and you will be surprised at how he will not admit his own errors.

It can happen to the expert as well.

But an expert for the expert of the contractor/the trades seems a bit schizophrenic.

With the GU, there are the trades, an architect, a site manager, and a client (+ expert).

In the architect's house, there are... oh wonder exactly the same people (or even fewer, if architect and site manager are the same person). So an expert also provides a few additional expert opinions there.

There are many general contractors/general planners and especially developers who manage quite well without a visible architect. Of course, for the approval planning, but then they never appear again and there is only the construction manager.