ᐅ Brown holes/spots on new calcium silicate masonry wall?!

Hello dear community,

Our newly built wall suddenly showed stains and holes that look like rust or burn marks. This occurs on both the interior and exterior walls.

The entire walls are affected; the photo shows a close-up detail.

The shed in question is covered but not fully enclosed.
We cannot explain these damages – efflorescence seems unlikely since sand-lime brick is not a natural stone. The wall is exposed to wind and weather outside, but not inside.

Does anyone have an idea what this could be?

Best regards,
Janine

Another shot from further away, please, to see the component.

At first glance, that looks like rust. Is there steel inside the drill hole?

Hello Alex85,

These are not drill holes – the damage appeared suddenly... attached is a larger photo.

Best regards,
Janine

Doesn’t anyone have an idea at all?

Best regards,
Janine

Rust, indeed

And where does that come from? From the inside? Is it some kind of efflorescence, and if so, why? These are not screw holes or anything like that. The wall was erected and has been standing there for 3 months now.