ᐅ Gray Stains on an Otherwise White Exterior Wall

Hello everyone,
the facade of our 2-year-old house is no longer white.

Here are a few pictures:

What could this be?
In the picture of the north side, the outlines of the insulation panels seem visible – or am I just imagining it?

We had similar “stains” already after one year. However, only in a few spots and mostly on other sides. We repainted those areas and it was fine afterward.

I don’t know how long these have been here – but they are on the back side of the house, which I just happened to pass recently and noticed this for the first time.

Thanks for your feedback.
Mario

This is the classic problem with ETICS (External Thermal Insulation Composite Systems). The facade is cold on the outside during winter, leading to corresponding moisture condensation—that means dampness on the facade. Insulation boards glued edge to edge instead of overlapping, so their outlines become visible due to slight thermal bridging.

Last but not least, a thin-coat exterior plaster was applied instead of a proper, thicker one.

The facade will need cleaning/repainting every few years if you don’t want to accept this appearance.

Alex85 schrieb:
Insulation boards glued edge to edge and not overlapping, so that their outlines become visible, causing minimal thermal bridging.

Could you please clarify what you mean by "edge to edge and therefore visible outlines" and "with an overlapping bond where no thermal bridges occur"?

You can also use tongue and groove panels or install two offset layers on top of each other. Naturally, both options are more expensive than simply gluing plain panels edge to edge.

After two years, that is quite fast, of course... but nothing unusual...

Definitely a "visual side effect" of the minimal thermal bridges in the external thermal insulation composite system (ETICS). Brick veneer here in the north definitely has its advantages.