A house under €140,000?

Should I better buy a used house with such a small budget?

It may be different in Berlin in some cases - but here you get about 70m² condominiums from the 80s for around 140k...

Up until 2-3 years ago, it was still possible to get residential houses for 140 T€. Now they are around 200 T€.
A bit further out, it is still definitely possible – everywhere where the communities are shrinking, you can still get lucky for that money; but what you get is by no means an insulated house (I’m not even going to talk about plumbing, electrical work, etc.).

By no means do you let the nieces insulate, the nephews should not be affected either. :D

Sorry for off topic. ;-)

It may be different in Berlin in some cases - but here you get about 70m² condominiums from the 80s for 140k...

If the OP wants to buy something in Berlin or the Potsdam area, the answer for used properties is also: NO.

If at all, he must look (far) outside of Berlin in the Brandenburg countryside (so not the Brandenburg Berlin commuter belt either). Whether he then likes the location and (transport) connections remains to be seen.

but here you can get about 70m² condo from the 80s for 140k...

That's true, it's certainly possible here as well, but.... you must not have any expectations at all or even consider the idea of wanting to modernize. ;)

Does he have to build a house according to today's standards, is that a requirement? I always thought it basically only concerns [KFW-Kredit]. With lower amounts and the current interest rate, it is "almost" irrelevant.