Is that mold?

Hi guys. I'm new here and quite clueless. I wonder what is on the walls here. Is that some kind of mold or is it just some dirt? Can you simply tell that like this? Thanks and best regards

Good day,

this looks like classic algae formation on the plaster facade.
An expert knows more about that!

Regards

Good day,

this looks like classic algae growth on the plaster facade.
An expert, however, knows more about this!

Regards

If it is algae growth, would that be a bigger issue?
Thank you and best regards

No, the facade must be cleaned accordingly and then treated (Auftrag von neuen Schutzmitteln). The latter are sometimes already included in the paint. The cleaned facade is then painted with it.

.. if you want to prevent algae formation, insulation and a larger roof overhang help.

Great, thanks to you all!