Floor plan planning shortly before submitting the building application

They said that then one could start immediately with the construction after the earthworks. As I understood it, the delivery time for the prefabricated components is so long that after completion of the earthworks nothing happens on the construction site at first. And they don't find that so good considering the weather.

Ok, I understand that this is justified by longer delivery times due to the construction boom. On the other hand, you know that and can plan/parallelize accordingly. The shell construction probably doesn't start directly one day after the release of the workshop planning, or does it?

But they probably know better and can assess it more accurately.

A cast-in-place concrete wall is not a bad thing. However, prefabricated parts are faster. If their order was missed, this can of course be reversed. I would definitely ask if this has any impact on the schedule, in case time is important/critical for you. Another difference is that cast-in-place concrete according to WU guidelines in stress class 2 only needs to be 20cm thick, whereas the element wall must be 24cm thick there (as in both versions in stress class 1). But all of this can be researched.

Purely out of interest: why is in-situ concrete supposed to be faster and more robust against rain, etc.? I seem to be missing something...

Quite simply: prefabricated parts are either lost formwork (with corresponding interfaces to the in-situ concrete infill), or themselves also monolithic, but for weight reasons more subdivided (thus associated with the problem of joints). In this respect, I even see a slight quality advantage for the extra effort of shuttering and concreting on-site.

Prefabricated parts are faster though. If their ordering was missed, this can of course be reversed.

I wouldn’t call it missed. The wall elements don’t just come decentralised on demand from a 3D printer. Storage capacity is likely limited, so production orders pile up after a weather-related pause and get stuck in the queue. The self-help measure of rescheduling to in-situ concrete seems sensible to me.

Sure, I wasn’t concerned about the technical advantages of the in-situ concrete wall; I was aware that being "cast in one piece" has advantages over being "placed joint by joint." I just didn’t see the explicit advantage regarding "building the basement in the rain." Hence the question, because placing a prefabricated element sounds faster and more robust against water from above than formwork and impairing the concrete in case of too much rain. I was only interested in the time factor and robustness against weather influences.

But a different question regarding WU concrete basements and sockets. The wall thickness is said to be 25 cm. Can you install flush-mounted sockets there, or does that weaken the watertightness too much in that area?
-> Soil report indicates temporarily rising seepage water (clay soil)

Normally install sockets or rather pre-wall installation and put the sockets there?

I just didn’t see the explicit advantage regarding "building the cellar in the rain".

You are probably right, the in-situ concrete would of course be "diluted", but with more than a light drizzle you probably wouldn’t do it anyway. Some construction managers might also quickly come up with "plausible" reasons off the top of their heads.

They told me that the electrical wiring is also easier to install with the new version.