u/Wiseoldman111

US-NJ, 1910 building
less than %1 is how likely? I forgot the tags and don’t know which layer it refers to.
It is from kitchen wall next to window but I don’t know if whole apartment walls are like this

It is leaking and can it be fixed or replaced by bigger one ?

[effacé]

This is view from my renovating second floor. I want to replace drains upper floor but should it be done from this level? If so if I renovate upper floor later on does it damage already done drains ?