Convert an inner terrace into living space?

Hello 11ant,

I'm on it. The heating replacement is already firmly scheduled and the external insulation will also be arranged, thank you very much for the tip!

and the external insulation will also be clarified,

It does not necessarily have to be on the outside.

Hello Haeuslebaur,

does the outdoor seating area have a proper concrete slab or is the steel support "only" standing on an isolated footing?

If you want to keep it rather open anyway, then floor-to-ceiling windows made of aluminum or a post-and-beam facade would simply be suitable. If there is a concrete slab, you can simply place these facades on it. Similar to a conservatory, but with the existing solid ceiling above.

The existing steel support could then be clad, for example, or painted in the color of the new facade.

Personally, I would prefer glass there rather than solid walls.

Does the outdoor seating area have a proper base slab or is the steel support "only" standing on a single foundation? [...] Personally, I would prefer glass there rather than solid walls.

I understood the OP to mean that he would preferably like to "shift" the window openings of the existing structure to the new exterior edge. From the year of construction, I conclude with high probability that here the base slab is cast onto the cellar ceiling – back then without "Isokörbe," and thus it is even quite welcome that this area is now to be assigned to the "interior."

I understood the OP as if he would most like to "move" the window openings of the existing building to the new outer edge. From the year of construction, I conclude with high probability that the floor slab is cast against the basement ceiling - back then still without "Isokörbe", and thus quite welcome that this area is now to be assigned to the "inside".

That's right, one could interpret it that way too. I agree with you.

At the moment, the two exterior walls are 70% glazed with large windows, that should be the case again, would like to reuse the windows.

I overlooked the "again".

Hello Simon, thanks for the valuable tips.

does the freestanding seat have a proper base plate or is the steel support "only" standing on a single foundation?

Unfortunately, I (still) don't know.

I understood the OP to mean that he would preferably like to "move" the existing window openings to the new outer edge. From the year of construction, I conclude with high probability that the base plate is cast onto the cellar ceiling - back then without "Isokörbe", and thus quite welcome that this area is now to be assigned to the "inside".

Exactly, that is the plan with the windows (possibly also a new sliding glass door or similar). Regarding the base plate: Would that be positive and no new base plate would have to be laid? (Please excuse me, I am really not very skilled in construction topics yet).