Is a folded plate staircase possible between load-bearing walls? (Visually)

I don't quite understand the argument of the general contractor. After all, every staircase will be anchored somewhere in the party wall. Sound problems could be avoided – for the neighbor but also for yourself – by using a concrete staircase, which is covered in a "folded structure" look.

I don't understand that either – if the staircase runs between two load-bearing walls anyway, then a precast concrete staircase is absolutely suitable.

Thank you very much for the help!

Originally, a concrete staircase (for soundproofing reasons, etc.) was planned; unfortunately, due to the corona situation, threatened delivery times (or delivery difficulties at the concrete plant) of up to 18 weeks arose. Therefore, we were advised to switch to a wooden staircase, "if we could live with that," otherwise there could have been timing problems with the installation of the reinforced concrete ceiling. Since the building authority has now unpredictably delayed the construction by 3 months, we could have stuck with it. The trade (wooden) staircase will be awarded separately to a stair builder (a larger provider with branches throughout Germany); so far, we are only waiting for a first offer.

If I understand the term "aufgesattelte Treppe" correctly, it just means that a stringer runs underneath the staircase, so it is only visible from the side and below? We can live well with that too. That could certainly be designed nicely as well. Can a higher noise level be expected?

a concrete staircase (for soundproofing reasons etc.)

I don’t agree with that.

we were advised to switch to a wooden staircase, "to see if we could live with that"

Who are you now: buyer of a concrete staircase or part of a building owners’ association as client of a general contractor?

otherwise there could have been timing problems with installing the reinforced concrete ceiling. Since the building authority has now unpredictably delayed the construction by 3 months,

At what stage is the construction (or the project) currently?

The trade (wooden) staircase is being subcontracted separately to a staircase manufacturer (larger provider with branches throughout Germany); so far we are only waiting for a first offer.

From whom, for all three houses or individually?

If I understand the term "saddle staircase" correctly, that only means that a stringer runs under the stairs, so it is only visible from the side and underneath? We can live with that well. That could certainly be designed nicely. Is higher noise generation to be expected with this?

Yes, saddled stepped stringers lie under the steps. Unclad that should not cause high noise generation.