Water ingress through the ventilation system, what to do, liability?

Storm damage.. that should be part of the building insurance; if water damages something in the household contents, then the contents insurance applies accordingly.

Provided there was actually a storm, which is only the case starting at BFT 8. Here in NRW, I haven’t measured BFT 8 on recent weekends despite gusts and heavy rain, all just barely "only" 7. But I only measure in 10s intervals. Ultimately, the data from the DWD or another official source surely counts.

Otherwise, it could be heavy rain; there are minimum values in l/min for that as well, which are covered by elemental insurance if such exists.

We had a loose brick, it was paid directly by the insurance (NRW). When Sabine raged, it was often even stated directly on the homepages of the insurers that damages up to amount X are settled without prior examination (of course only after submitting the invoice). That's how it went for us too.

We had a loose brick, it was paid for directly by the insurance (NRW). When Sabine raged, it was often even stated right on the insurers' homepages that damages up to amount X would be settled without prior inspection (of course only after submitting the invoice). That's how it went for us as well.

It is not wise to handle minor damages through insurance. It all goes into the claims ratio, and eventually the renewal comes (termination by the insurance).