Condensate formation

Hello and good evening. I have a fundamental question... If I have drywall on the walls in the attic... And let's say some people are up there or condensation somehow forms under the panels... Then it will remain there because of the vapor barrier if it is airtight between the foil and the drywall and evaporate. Right? If it were leaky somewhere, the condensate would go through the foil into the insulation wool, but there it could escape to the outside because of the diffusion-open underlay, right?

Condensate (liquid water) forms when humid air is cooled below the dew point or when it comes into contact with a surface whose temperature is below the dew point (cf. glasses wearers in winter). The vapor barrier prevents water vapor (!) from the humid indoor air from entering the insulation and then condensing there -- due to the lower temperature present somewhere in the insulation.

Condensed water on/under plasterboard will run down the boards; it will not pass through the vapor barrier, which does not allow water to pass through. Eventually, this water will evaporate, yes.

In the case of a leaky vapor barrier on the roof slope, liquid water would have to overcome gravity. This is conceivable through capillary action, but IMHO unlikely under realistic conditions.

Through leaks in the vapor barrier, however, moist -- relatively warm -- air from the interior can get into the insulation. There, under certain circumstances (cold insulation), the water vapor would then condense.

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However, moisture -- relatively warm -- air from the interior can enter the insulation through leaks in the vapor barrier. There, water vapor would then potentially condense (cold insulation).


that was my mistake. thanks :)