Wood fiber vs. mineral wool vs. Styrofoam in timber construction

Which of these insulation materials is better in the long term? With Styrofoam, a vapor barrier is definitely used because any moisture that may penetrate cannot escape through the Styrofoam. With a mix of mineral wool and wood fiber, a vapor retarder is used; with wood fiber alone, usually only a windproof sealing membrane is used.

Basically, from inside to outside
- Gypsum board
- Vapor barrier / vapor retarder / diffusion-open windproof membrane
- Timber frame + mineral wool or wood fiber
- Gypsum board
- Styrofoam or wood fiber
- Plaster

a) Vapor barrier + mineral wool + Styrofoam
b) Vapor retarder + mineral wool + wood fiber
c) Diffusion-open windproof membrane + wood fiber + wood fiber

What would be the advantages and disadvantages of each construction? How significant is the absence of an installation layer in each case? Is it less problematic in c) because any penetrating moisture can also escape again?

U-values and price I would guess. Personally, I would tend towards wood fiber or mineral wool. However, Styrofoam is not that bad either.

Thermal insulation almost always needs to be brought to the same level regardless of wall thickness. Expanded polystyrene sometimes has advantages over wood fiber or mineral wool in terms of thermal insulation - so the wall can be thinner. For summer heat protection, however, mass counts - here Styrofoam is at a disadvantage. Also sometimes a question: sound insulation - mostly also a matter of mass, but also other properties of the building materials used (including windows and ventilation systems, but also: what does the wall construction actually look like). Installation level: Why give it up? The biggest problem without an installation level: the tightness of the concept. Expanded polystyrene... where it is justified, OK. But sometimes there are better alternatives (unfortunately usually more expensive). Woodpeckers love Styrofoam...

Yes, I rather mean that the biggest problem with forgoing an installation layer in a timber frame construction is that moisture can penetrate the insulation. That is, in the anyway vapor-permeable construction method c), in my opinion, not a problem.

Would small airtightness faults be a big problem? As far as I know, no house is completely airtight. In every solid building there are very fine cracks in the interior plaster. Hence the whole charade with painter’s fleece...

The cracks in the plaster have nothing to do with the air tightness...

Not? Why? The airtightness layer in a solid house is, as far as I know, the interior plaster. Cracks in the plaster make the house, in my opinion, leaky here. Although, as I said, no house is airtight anyway and such cracks, seen over the total area, do not really matter.