Retroactive balcony mounting device

It's not impossible, it's just effort.

As I said: If I, as the builder, want to do something myself (or provide it on site), it is my responsibility to become knowledgeable or to purchase expert support (architect, engineer, ...). Afterwards standing there and saying "I'm an amateur, I couldn't have known" does not show thoughtfulness...

Apparently, however, the wooden beam is also too thin.

What wooden beam?

The railing cannot be attached on the balcony either, since there is insulation here as well as a zinc parapet.

Where and how?

Apparently, a major dismantling is necessary.

Says who and why exactly?

But why build the balcony and not give any indication that installation is impossible in this design?

Why order a balcony without a railing and not ask how to attach a railing? Once again: You order a balcony without a railing. Period. Why don’t you answer questions? Why don’t you show plans and pictures? You don't even say what kind of railing it is.

How is he supposed to know what you want to build? Glass railing? Stainless steel on the balcony? Wood? Attachment to the facade? Attachment on the balcony? Attachment in front of the balcony? There are dozens of possibilities.

If you handled and communicated during construction the same way, it is no wonder if the general contractor just delivers what you ordered. And if you don’t provide any further info here in the forum, you will get exactly what is happening now. Guessing, requests for info, no advice. Sorry, please don’t take this badly. But so far you have been whining for two pages that something can’t be attached to some beams somehow. My crystal ball is really overwhelmed with this.

exactly said what’s going on!

But now it’s up to you to make the best of it. My brother and I, for example, deliberately decided to be "construction managers" with all the consequences. I would never have done that alone (wouldn’t have trusted myself). That’s a lot of responsibility for a very large amount! Either you hire a construction expert as a layperson or “hire” a construction manager for the appropriate fee. The point is to have someone with expertise on YOUR side. It’s not that the general contractor / builder is the “opponent,” but they tend to think more about themselves than the client. Not doing either is apparently a common naivety you are certainly not alone in! Really, no one here wishes you any harm. But now you have to deliver in the form of the aforementioned documents / information.

Well, as a layperson, I simply cannot know all the requirements of how and where something must be constructed so that everything works afterward. When I buy a balcony, I assume that a railing can be installed.

But precisely this "Well, as a layperson" must inform itself in advance whether this layperson actually has the further experience. If I consciously leave out the flooring, I cannot complain that as a layperson I cannot foresee that putty work still needs to be done in addition to the flooring. If I do something in EL, I must inform myself in advance whether I am even capable of doing it.

I also assume that the builder, who does not order a railing, is personally responsible for the timely preparation of the mounting, but it would be normally polite if the contractor asked about this decision in good time.

The gentlemen are not paid for thinking along or even advising. They just stubbornly stick to their routine, the way they have always done, and that's it. On the other hand: due to the shortage of skilled workers, one rushes from construction site to construction site. Surely, there is neither the time nor the patience to take people who want to do something on the construction side under their wing.