Old building or new building?

Even if it would only cost 100k... We would now (assuming we could get craftsmen immediately) have to live on a construction site for at least 1 year... + I don't think anyone would add the 100K for renovation on top of the house to me... Who knows if we will even get back what we have now with our already 30K + then possibly 100K renovation costs... ...

This concerns the missed, value-preserving renovations, except for the extension. During my viewings, I always went through the property, noted what needed to be done, and added that on to the purchase price. If the all-inclusive price doesn’t match the market – next. New construction isn’t possible with your money. Sell the place, head to Brandenburg, Mecklenburg-Western Pomerania, or deep Saxony. There it will work with the money plus a small loan.

To me, this clearly looks like burnout from the renovation. Plumbing and the extension will take a year. The building permit alone will take months. How about not only a holiday apartment during the busy phase, but directly a rental apartment until it's finished? For about 1.5 years. You gain distance and strength to complete the project calmly and without stress with an architect or general contractor.