Optimize and expand the floor plan of an existing house

Year of construction of the house and barn?

How or where would you get into the attic?

The year of construction is 1930 for the house and 1931 for the barn. There used to be a staircase in the current dining room; now there is only a hatch with a folding ladder. We would then install a staircase there again, as the "hole" is already present.

But a stable is actually always an outdoor area, or what is meant by that?

Outdoor area means a zoning classification in which, colloquially and simply put, only farmsteads and hunting lodges are allowed, and basically only operating apartments for the farming family are permitted.

When was the last time it was renovated, e.g. electrical, sanitary?

Based on the sketch, one can't really get an impression. For example, I can imagine many things like a stable. What does the whole thing look like in a photo or how is the location/neighborhood?

I have seen renovated houses where the upper floor/attic was widened and extends beyond the ground floor. There are many ways you can go. Since you bought the house, demolition of the stable with a new build of a bungalow, e.g. for the mother and later for you, probably is no longer financially feasible? What is the budget?

In order to use the stable as a residential building, a change of use must be applied for, right?

To be able to use the stable as a residential building, a change of use must be applied for, right?

Yes, I assume so too. We will take care of it.

To use the stable as a residential building, a change of use must be applied for, right?

Addendum to post #8: agricultural or forestry use typically has to dominate when dealing with an outer area.