Timber frame builder replaces OSB with gypsum fiber boards - equivalent?

Yes, I will do that! I will.

BOTH OSB boards are replaced by gypsum fiberboards.

I also do not have OSB boards in my exterior walls. I see no problem with that as long as the overall system is right. The bracing of the timber frame must be achieved and, of course, wind tightness as well. Both are possible without OSB and also without foil.

Yes, thank you for your assessment. I also hope by now that the relatively higher scarcity of wood will last long enough until my walls are made :cool:, this should also apply to the interior walls.

It would be interesting to know how other prefab house manufacturers are reacting. Ours has not yet added a * asterisk to its product list for new customers, in which it would announce, for example, that it will not install OSB for an indefinite period.

A bit late, but since I have a timber frame house, a few comments, as quite a lot was wrong. The vapor tightness should decrease from inside to outside, and the diffusion openness should increase. OSB boards glued or taped in tongue and groove are diffusion-tight. Double gypsum fiber boards are not. Therefore, you need a vapor barrier on the inside. On the outside, I need a windproof layer that lets moisture that has entered escape. Therefore, no OSB on the outside. If someone thinks of doing it without vapor tightness, they take a risk and have less insulating effect. Also, OSB is significantly easier when mounting shelves, pictures, or other items.