Insulating the attic, avoiding mistakes?

So we have no windows up there. It's really just a tiny attic. But on both walls, there is a ventilation pipe for the airflow!

Then it depends entirely on the water vapor generated, the water vapor diffusion resistance of the affected components, and the volumes. Because the roof will be driving rain tight and the slight airflow cannot be sufficient, the roof structure is always affected by moisture. It is no coincidence that insulation of the top floor ceilings is not favored in particularly protected buildings. A simple measurement on the wooden components provides clarification before the beams turn green.

"Schlagregendicht" does not mean less draft. My roof is tight, but wind blows through like nothing. Under the eaves, there is simply an open section, only animal protection grids are in place there.

If there is a draft, you can save yourself the insulation. If insulating, then airtight. With all the advantages and disadvantages.

@

Of course, the underlay inhibits air exchange, see the Sd value of the membranes. The ventilation, if present, takes place outside, like the eaves.

The question of insulating the conditioned space now also appears completely pointless if the roof space is under continuous ventilation.