Slice a "basement wall"

[Arne999]

I have an old barn with a space under the foundation wall, making it somewhat like a basement for the barn. There's old deteriorated plaster (20-30 sqm) on the walls under the foundation wall, and I'm looking for a simple solution.

It's not the driest space, so organic material is out of the question.

Option 1: Re-plaster, but I've plastered enough and I'm not keen on doing it at all....

Option 2: Frame the space with metal studs and install some kind of board that's ready to use immediately.

The question is whether there is a good alternative? I've looked at facade boards/base boards, but they cost 400 SEK per sqm, which is a bit steep....
Plasterboarding might work... I plan to have a dehumidifier in the space but not heated.

 

[tergo]

Plastering might work… I have thought about having a dehumidifier in the area but not heated

Outdoor plaster might possibly work if you have a dehumidifier

 

[Arne999]

outdoor gypsum could possibly work if you have a dehumidifier

outdoor gypsum apparently should not be surface-treated, otherwise, it was a good idea.

 

[tergo]

outdoor gypsum apparently should not be surface-treated, otherwise it was a good idea.

it withstands a little moisture without treatment

 

[Arne999]

Well, but for aesthetic reasons, I don't want to have a green exterior gypsum board as a surface layer, but would rather paint or alternatively put up a board that is ready-made like a façade board.