New installation layer for house with plank frame

[VLJ]

Hello,

We have a 1920s house with a plank frame. The construction is described in an old building permit application as:

What is not apparent here is that between the vapor barrier paper and the 3/4 wood fiberboard, there is insulation where the electrical wiring has been routed.
We now need to redo the electrical wiring in the living room and are faced with replacing the wood fiberboards.

I'm considering fixing the installation layer so it's 45 mm, then installing 45 mm Hunton Wood Fiber Insulation in this.
Then replacing the wood fiberboards with Fiber Gypsum.

The idea is to sort out the electrical wiring, then get a good base for wallpapering without doing anything that could risk creating moisture problems in the old house. Hopefully, the new insulation will also insulate a bit better than the old one. The advantage of fiber gypsum as I see it is that the wall will not be thicker than it is currently.

What do you think about this?

 

[Oldboy]

Fiberboard was used because it insulates, which gypsum does not. With a slightly thicker insulation layer in the installation layer, it probably evens out roughly in terms of insulation capacity. Gypsum is about as vapor-permeable as wood panels, so the construction should work equally in terms of moisture as well. Fiberboards provide a nicer acoustics compared to the hard dense gypsum, but even here the differences are probably relatively negligible if it only concerns 1-2 walls in a room.