After I reported about this stain a few days ago, my general contractor gave me the all-clear yesterday. It does not come from the roof or the insulation, but was already there before the drywall construction. Our general contractor had already been aware of this.
It is probably due to a sheet of the dormer, which will be plastered later and then receive its final waterproofing. A few weeks ago, the roofer already sealed it with a sealing tape so that no more rainwater could get in in the meantime. Therefore, it also did not affect the insulation.
Otherwise, our staircase builder was supposed to do his work this week – but he simply forgot to finish the staircase. Let’s see if he comes on Monday then. Without the staircase, the painter can’t do anything either. He will also only come on Monday now.
Today we will finally continue with the interior window sills and possibly the tiles – due to the screed drying, not much has happened in the last few weeks.