@PeterHuber …every situation is different and all policy details are different as well.
It is quite normal for “proof” to be asked for. This is why we encourage everyone, after a storm or major happening… to report damage to their property… to their Mairie, so that info can be collated to enable “proof” to be provided to Insurance companies.
One person saying “it tore the roof off” when none of the nextdoor neighbours were touched…does not hold as much weight as 6 neighbours all complaining about the same “storm”.
In the Original Poster’s case, if the crack is the result of work done eg the roads/drains… the Enterprise concerned will have insurance.
If the Area is certified as having problems due to the drought (ask at the Mairie)… then the householder’s Insurance company may well be prepared to cough up…depending on the cover the Householder pays for.
We do not know enough about this particular incident… I am just offering possibilities to see if anything might “ring a bell”…