Completely rotten interior wall - how do I fix it?

[magstorm]

I don't have any more pictures either, but I'm wondering what the blue plastic is for that's on the inside of the träulliten? Is it some kind of moisture barrier or what's it for? The plan right now is to glue a chipboard on the inside of the träulliten, but I'm not quite sure what to do with the plastic?

 

[hempularen]

In the pictures, it indeed looks like the rotten part is a load-bearing plank wall. So it's a solid wood construction. Therefore, you should definitely prop it up. And preferably as soon as possible, regardless of whether you demolish now. Because the wall has no load-bearing capacity at the damage.

Regarding whether you can close the roof before repairing the wall, difficult to see. But you should be able to determine if everything damaged is accessible for replacement from underneath.

 

[magstorm]

In the pictures, as mentioned, it looks like the decayed part is a load-bearing plank wall. It is a solid wood construction. So you should definitely prop it up. And really as soon as possible, regardless of whether you're going to demolish it now. Because the wall has no load-bearing capacity at the damage.

As for whether you can close the roof before you repair the wall, it's hard to see. But you should be able to assess if everything damaged is accessible for replacement from below.

Yes, it is correct that it is a load-bearing plank wall. I wrote/thought wrong.

How far from the wall should you usually prop up?

 

[Stefan1972]

If you're going to do that properly, it's probably easier to cut away and build a new wall using normal methods. It was likely poorly done when they did something before. Hence the strange boards and plastic and probably much else you have found.

 

[Thomas_Blekinge]

If you want to repair the damage permanently, you should tear away EVERYTHING that is affected. Also remove the blue plastic, it surely isn't doing any good. If it was supposed to be a moisture barrier, it hasn't helped much. Prop up in several places and ensure that the floor is supportive. Adjustable props can be rented for little money.
Rebuild the wall with fresh timber, either as a solid plank wall or with studs and cavities for insulation. There are different opinions about plastic film, yes or no, I would skip it.
Wait with the ceiling until the wall is repaired and cover with a tarp in the meantime.
Take the opportunity to run new electrical wiring to outlets and switches now that the wall is open.