astarte wrote:Friends are renting in this complex and there is indeed mould in their attic.
Happened to a friend's complex a couple years ago -- the problem was fixed but he sold immediately afterward, before more problems were discovered. The attics should be ventilated so this doesn't happen, but sometimes the contractor cuts corners and the moisture has nowhere to go, causing mold in the attic and even down the walls.
I also worked in construction years ago and saw lots of stupid mistakes made by workers who were stoned or who drank several beer at a nearby pub during lunch. It happens.