House purchase from the year of construction 2014 with 118 sqm living area and basement

Dom, you don't have to defend yourself here: if you like it, go for it. It is not too expensive. It is not cheap. It is simply priced correctly. K.

Floor area ratio 0.4, plot ratio 0.7. Believed permitted up to 2m wide, max 1/3 of the total roof length of all dormers.

The living room is as wide as our current one, with the dining room even somewhat larger than at the moment.

Then try to get it.
Dormers, extension etc are options in case your fears do come true

So we looked at the house again. In the pictures, it looks significantly smaller and less comfortable than in reality. It is not insulated but built with 42cm bricks plus plaster. Another plus point for me, I don't like that styrofoam stuff. For the remaining work in the basement, basically everything is there, we will do it ourselves. Carpenter etc. all in the family. A paver is also available for the outdoor area. We also get the building materials at purchasing price, since sister-in-law works at a building material dealer. We also had independent support during the viewing with a similarly positive assessment. Thank you very much for the active participation and the suggestions.

Sounds good. Good luck.

Good luck
A feedback on whether it worked would be nice

It worked....We already had the approval anyway, yesterday the drafts for the [KV] came from the notary. Of course, something can always happen before the signature....But we are not expecting that.