Floor plan optimization single-family house 140m2 on narrow plot

What do you mean by rubbish? At 100k I would consider preserving the basement. You can even preserve parts of the house. It doesn't look that bad in the photo. Show all views of the house, preferably with photos.

Gladly! Floor plan: Exterior views: Maybe I will go to the property again today, then I can take photos from the outside. I could also take photos from the inside. However, I must say that the house is still fully furnished.

With a 300k budget, you should do that.

Originally, we had the idea to completely renovate the house, but we were advised against it.
Then we thought about at least using the basement and building a new house on top of it.

But the basement looks really bad, I hope I can provide visual material for it today at noon.

This is how the basement/house stands on the property. So yes, it fit.

Then the direction would be clear for me: continue using the basement, extend the annex over the septic tank as far as desired. For a utility basement, I consider an exterior entrance sufficient, so the stairwell could be covered if the stair position interferes with the floor plan above. I wouldn’t have time before October (except for a preliminary discussion), but I am definitely interested in the project.

I have drawn it a bit more precisely again.

You should read everything together once. The 300 thousand is only supposed to be for the house OK foundation slab, the basement is calculated separately with 100000.

So 400k plus deep demolition with all bells and whistles, which is no small matter. If the basement stays, all connections also remain.

I have drawn this a bit more precisely again.

Maybe again with a vestibule and terrace, that would be perfect.