ᐅ Pattern created by insulation panels on exterior wall

Hello,

a pattern is becoming increasingly visible on the exterior walls of our house (built in 2007). Black lines appear where the insulation panels meet.

This is especially noticeable on the north side. On the south side, there is no visible effect, and on the other sides, it is somewhere in between.

We have a standard white exterior render.

The general contractor claims this is due to the "damp" north side and says there is "nothing he can do about it."

Does anyone have a good tip for us?

Regards,
Christian

In my opinion, these are classic thermal bridges because the insulation was installed poorly! You can often see the fixing plugs showing through the façade after a few years if they were not properly recessed, or if a cheap version was used...