ᐅ Damp spot in the attic – what could it be?

Hello everyone,

We are approaching the end of the construction phase. Yesterday, when the tiler wanted to start tiling the bathroom on the top floor, I noticed a damp spot in the corner as shown in the picture. According to the architect, it could be condensation. The roofer is coming tomorrow to inspect the roof again, but he said it would be much worse if the roof were leaking.

Construction started on 01.05.2017
Screed cured for 9 weeks
I don’t remember exactly how long the interior plaster took, but it was longer than the screed

The membrane visible here seems to be wet or damp in the upper area (directly below the edge of the green drywall panels) where it connects from the wall to the roof structure. From my perspective, this suggests condensation issues and points to a problem with the roof. It looks as if the membrane is sticking to the beam because of water. Or am I mistaken?

Do you have any pictures of the shell construction from that spot?
It could be a thermal bridge, poor planning, or incorrect execution, which then causes condensation.
Just try measuring the surface temperature.
A covered roof usually cannot be leaky.

I find it surprising that the edge of the membrane is simply visible at the bottom. It’s probably the same at the top, but you can’t see it there due to the blur. Shouldn’t it be sealed or taped somewhere? Is that the exterior wall?

Faulty vapor retarder. Perhaps the wall connections are not properly installed. The insulation is certainly wet. It is essential to check this thoroughly; otherwise, you will soon have a mold problem (and many others).

I need to check the laptop for pictures of the shell construction tonight. We have a middle house in a terraced row. It has rained heavily and snowed in the past few days; before that, there was nothing I would have noticed. What would you suggest I could do?