Wood fiber boards instead of underlay membranes

I am also curious how it works without an underlay membrane.

=> hydrophobized wood fiberboard (e.g. bituminized or latexed)

I came across this, companies like Gutex, Pavatex (ISOLAIR), and Celit are involved.

THESE treated wood fiberboards are supposed to be diffusion-open, windproof, and waterproof, right?!

I have seen too many roof structures that had a wood fiberboard and thereby caught a great mold infestation.

But the left photo was from a new building, right?

I have seen too many roof structures that had a wood fiberboard and thereby caught a great mold infestation.

But that is a solid wood boarding combined with probably a missing vapor barrier!

And why were you not told/offered OSB boards? They are diffusion-tight and suitable “instead” of the foil.

Ah, sorry - it's about the [Unterspannbahn].. Please forget my answer

Gutex and Pavatex seem to be very active, many anchor dealers. Celit seems to me to be "dead," hardly any anchor dealers to be found anymore .. CAN these products from Gutex and Pavatex really be used as a full-fledged replacement for these underlay membranes? Experiences?