I don't know if this is the right place in the forum to post, but I'll try here.
Today we discovered some spots on a wall in the upstairs of the house. See the pictures. We immediately thought that the roof is leaking.
Once in the attic, the roof looks fine. No broken tiles or anything. The insulation looks dry. The chimney, which is some distance away, is also dry. It's impossible to see what it looks like under 50cm of insulation.
Condensation from ventilation pipes or leakage from pipes? According to drawings and practical reality, no pipes should go through or over the wall. Neither ventilation nor water to any element.
It is only one side of the wall that has symptoms.
We have no memory of doing anything strange recently. We haven't spilled or sprayed anything. The weather has been dry and rain-free lately, so it's unlikely to be leakage or condensation.
There is also a spot behind the chimney on the other side of the door that is on the wall.
It is almost a bit oily and not so watery. Odorless and tasteless. We have wiped the wall and no new build-up has occurred in 3 hours. We wiped with a little dish soap and water, and that area doesn't have any spots yet. It's gypsum and behind that is an OSB board and insulation.
What is happening with the wall?
2 theories.
1. It's leaking from the chimney somehow and running diagonally to the wall.
2. The OSB board has after 10 years worn out and is starting to release glue and resin? The sun shines on the wall in the morning/forenoon.
Does anyone have an explanation for the wall leaking? Do we have a leak that we need to take care of?
