Came across wood framed construction and was wondering what is the intent of these panels. Fireproofing or just to catch water percolating through the wood framing.
Looks like a cheap-ish interior finish similar to a standing seam panel. I doubt it's for fireproofing, because that's usually gypsum boards in these cases. It's not for catching water, because waterproofing is applied to the top of a deck, not the bottom of joist.