Can Fermacell boards be screwed directly onto a panel wall?

Good day

I am new to the forum and would like to briefly introduce myself. I am from Switzerland, 33 years old, and with my wife, we were able to fulfill a dream by buying a house. The house is about 170 years old but relatively well maintained. The house is a [Rigelbauwerk] filled with rubble stone. It has been renovated several times over the years and expanded in 1970. The exterior facade is clad with [Eternit]. The interior walls mainly consist of wooden paneling but are otherwise well preserved. Most windows will need to be replaced in the coming years. The attic was completely insulated and converted in 1985. Two years ago, the house was also equipped with a solar system.

Actually, we first wanted to renovate some rooms and replace the windows. However, in order not to just start and make unnecessary mistakes, we decided to have the house inspected by an energy consultant first. He will look closely at the insulation and advise us on the order in which we should proceed with the renovation.

Therefore, we decided to first carry out just a few painting jobs in the well-preserved attic. The sloping roof and several walls are clad with paneling. One wall is plastered. We now want to spray paint this sloping roof.

On one paneled wall (wall length is 11.5m - 1/3 of that is an outer wall, the greatest height approx. 3.5m), we want to apply plaster. As a base, the wall should be lined with [Fermacell] boards. I want to carry out these tasks myself together with my father.

Now my consideration is as follows: The wall seems well insulated and the paneling is in good condition. Therefore, I now want to attach the [Fermacell] boards directly to the paneling. For this, I would first screw the paneling to the existing battens to ensure that the wall is stable. Then I would firmly screw the [Fermacell] boards to the paneling and have the plaster done by the painter. What do you think about this? Will this construction hold and what should I pay attention to? Thank you very much

Regards Schapo

Wouldn't it be reasonable to find out what the wall looks like under the wooden panels? At least I would be interested. We had something like that too, but everything was completely torn down and then something new was put on it.

Hello

Here are the pictures of how the wall was insulated in 1987.
In the first picture, you can see that the wall is attached to the support beams at the bottom and top.

The distances of the battens are already quite large, furthermore the gypsum fiber screws should land in the battens, only in the paneling it is not very stable. We did it similarly with our interior insulation, but with smaller batten distances (there were regularly inserted cross battens). I stand by my recommendation to remove the paneling and screw the fiber boards directly (and precisely) onto the battens. They already weigh quite a bit and the substrate should be stable and not bend.