Assessment of the cause of mold after renovation

such questions come up almost every week

https://www.hausbau-forum.de/threads/flecken-an-kellerwand-waescheraum.41299/#post-528775

posting #2

so:
- consult a hygrometer,
- check wall moisture at various spots (pipe leakage?)

Even if it was done by so-called professionals.
(here various "professionals" have already renovated, but not a single trade was flawless)

Ah thank you for your assessment. Yes, I remember the black mass! So that was definitely applied...

By rising moisture, what exactly do you mean? So what would be the cause of that?

I am familiar with rising damp in walls that are in contact with soil (simplified), such as, for example, basement rooms. The water rises from the bottom upwards. A remedy can, among other things, of course, be the removal of the moisture. Alternatively, a so-called horizontal barrier can be injected into the masonry to prevent the moisture from rising. However, this would not yet eliminate the cause.

What exactly do you mean by rising moisture? So what would be the cause of it?

Depending on the building material, water is drawn up through the concrete/stone above the water level due to so-called capillary action. For example, in aerated concrete blocks, lean porous mortar, etc.

Below the "big solution" of wall excavation and sealing, there is the so-called silicification. For this, holes are drilled into the masonry every few centimeters, into which a sealing liquid (similar to a primer) is dripped. This can take several days but involves little work during the dripping process. Afterwards, the holes are re-mortared.

But if I understood correctly, rising damp rather affects rooms that have contact with the ground, such as basements or the ground floor. However, the affected room is located on the first floor. There is nothing in the basement or on the ground floor...

But if I understood correctly, rising damp rather affects rooms that have contact with the ground, such as basements or the ground floor. However, the affected room is located on the first floor. There is nothing in the basement or the ground floor...

Looks like water damage to me. Too wet, too sharply delimited for "just moisture." Maybe a pipe connection came loose, allowing water to leak out. If it was well sealed, you wouldn't see anything on the ground floor either.