The biggest missing detail for me is the actual monthly total. Does the €3,493 include any building charges, heating or other utilities, and how would usage-based costs be billed? Without that breakdown, it’s difficult to compare the duplex with other Berlin rentals.
Agree with Carlos on defining the scope first, although I’d still reserve contingency rather than assigning every dollar. Before ordering finishes, map the sequence: investigation and any permit-dependent work, opening-up, plumbing/electrical corrections, moisture repairs, wall closure...
Cross-market comparisons work best when the definitions travel. Price per square metre is easy to compare but can conceal condition, tenure, outdoor space and whether transaction costs are included. I’d pick one Berlin example and ask members elsewhere to model that same fact pattern in their...