Renovation needs for a house built in 1939: How much will the renovation approximately cost?

There are simply too many eventualities and uncertainties/problems involved in this project for us, which we neither want to handle time-wise nor financially and eventually certainly won't be able to anymore

We also live in the neighborhood. There are still many houses here from the 1920-35 period, built in difficult times, and 100 years of use are over. Initial approval for the erection of a garden shed or a very small house and expanded and remodeled over decades. These houses are often junk, as is evident during demolition.

Thank you very much for your great advice. We will now tackle the "Barthel Strategy" and cycle through our neighborhood, make our desire for a home/plot known among friends and acquaintances, as well as canvass the local real estate agents.

That is very good, except for the agents – Barthel tips deliberately avoid them. What comes through agents is qualitatively the opposite of what you can buy alongside the market. Competent agents are as rare as camels passing through the eye of a needle; furthermore, they are often called in to put problematic properties on the market. More in line with Barthel’s tip would be to address the care services. My club will probably also start in Q4 with the semi-detached house matching service.

That would be a project comparable to ours. If I subtract the land value from the total price, the 175sqm house (core renovation plus extension) including additional costs cost us about €600,000. We finished in 2021. It has not become cheaper since then.