Security deposit according to §650 of the Building Code

Our lawyer holds the opinion that the consumer contract (in our case negotiation protocol) takes precedence over the General Terms and Conditions, now the opposing lawyer argues that one does not exclude the other. Furthermore, the hierarchy (1. contract ...4. negotiation protocol) would be important, anyway, we want to continue building without interruption, the easiest way would of course be, I find an insurance, if you know one?

The R+V can only be concluded up to a maximum of 4 weeks after the first installment. That probably leaves only a bank guarantee, but that won't be a cheap pleasure.

but how did "Irschen" receive a guarantee if their contract is from 2018? that would interest me