Purchase decision small semi-detached house 100 sqm from 1930

Cavity between the walls about 6 cm, theoretically it should be possible to fill it with blown-in insulation, or am I mistaken?

Unfortunately, I am not an expert on insulation, but this blown-in insulation sounds expensive at first. Have you checked what it costs and how effective it is?

Here are the floor plans.
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I am amazed at how precise and clean the documents are – I wouldn’t have thought this possible in the 1920s or never imagined that everything was planned and documented so precisely back then.

I am not surprised that they are good. People weren’t any less intelligent back then.
But I find the cellar barn wonderful. It’s hilarious! What do you want to keep there? Pigs? Rabbits? Maybe chickens? Fantastic! :D

The upper floor is really hard to interpret. The heights would be especially interesting – I don’t see any at first glance. The roof structures – if they are roof structures at all – confuse so much that you can hardly recognize any walls. Maybe you want to redraw them? That would be great for the interested reader (like me, for example ;)).

The stable is now a heating room :D The oil heating is there.

Do you mean ceiling heights? I think I can make out the following:

Basement one 1.90 meters from floor slab to concrete ceiling, then 30 cm concrete ceiling and screed
Ground floor / upper floor one 2.50 meters from screed to ceiling, then 25 cm thick wooden beam ceiling, in the upper floor again 2.50 meters ceiling heights and a knee wall (?) of 1.04 m.
To the attic 20 cm thick wooden beam ceiling and over a width of about 1.50 meters a room height of 2.50 meters and then of course sloping roof.

I have to print out the floor plan and measure / draw it.

It’s already annoying that with a basement height of 1.90 meters no insulation of the basement ceiling will be possible.

Then something will probably have to be taken off the 2.50 meters ceiling height on the ground floor for insulation. But the screed is supposed to be removed anyway, so that will balance it out a bit.

On the positive side, the living space will probably be somewhat larger than assumed.

Unfortunately, I'm not an expert in insulation, but this blown-in insulation sounds expensive at first. Have you checked how much something like that costs and how effective it is?

Not yet. Maybe someone here can say something about it and share experience? According to plans, I would at least consider it possible, maybe I am mistaken.

Not yet. Maybe someone here can say something about it and share experience?

It is a completely normal and not too expensive process. These are Neopor beads, which are lightly coated with glue and blown in. The glue makes them stick together and form an insulation layer.

For the small house, I would now estimate around +/- T€ 5 in today's terms. But 6 cm insulation with WLG 33 you definitely notice.

The roof structures - if they are indeed such - are so confusing that you can hardly make out any walls. Maybe you'd like to trace them?

The confusion is truly considerable, and I’m afraid that tracing the lines won’t help either: as far as I can "make out," the architect seems to have "combined" the basement of one half and the attic of the other half in the drawing (?)

The confusion is truly not trivial, and I fear that redrawing the lines will not help: as far as I can "recognize," the architect here has "combined" the basement of one half and the attic of the other half in the drawing (?)

Yes, that is how I would interpret it as well.