Cold roof - Are roof windows necessary for cross ventilation?

At our place, the top floor ceiling is also insulated and the eaves and ridge have a ventilation grille.

That is a classic ventilated cold roof.

A roof that is insulated between the rafters and has a ventilation layer above the insulation and below the roof covering is also a cold roof. With a cold roof, it is important that the ventilation works, because ventilation is a constructive measure for wood protection. Otherwise, the roof structure will rot if the ventilation does not work properly. This applies whether the insulation layer is the top floor ceiling or designed as an insulation between rafters.

Warm roofs are never ventilated and require a vapor barrier so that the roof structure is not damaged.

DH in ventilated cold roofs make windows in the roof structure/attic unnecessary. Ventilation must work without windows.

The question about the qualification of the self-proclaimed construction consultant arises again. It is not a protected term, and even pizza bakers can be construction consultants.

Oh, I am just an amateur and share my experience with my own planning - and naturally this was also addressed by the architect/roofer, etc.

We also have a vapor barrier with a variable SD value from 0.25 to 25m.

Oh, all the way up to the ridge? Then ventilation doesn't matter.. If it was really done properly.

No - only the sloping ceilings and the intermediate ceiling. You mean now that we have to ensure that air circulates there, otherwise there could be damage to the rafters? (more isn’t there anyway)