Since it’s covered above what about just finishing it with soffit??
That’s what I’m planning on doing for the same circumstance at our new house.
That was my initial thought, but then I ran into 2 hurdles.
My first being that there’s a decent amount of snow/ice/rain and water that still gets in on the deck above despite it being covered. It’s tough to show but the sidewalls are all EZ screen making it basically open minus bugs. Because of that the lower ceiling has to be something that handles water and drains it uniformly(see pictures if they load).
My second hurdle is the FW thinks it should “match” her front porch and upper porch ceiling (see pictures), but I’ve tried to explain it’s not the same application and I can’t just hang nickel gap under a deck that lets water through like I could on the front porch that is protected by a full roof. It has to be some synthetic product with designated drainage.
My solution so far has been to drink beer whenever she brings up suggestions for it, but figured the IDO world would have a solid product.
Edit – It looks like the Trex product has some different finishes that could maybe do the trick if the FW approves. Thanks Supercat.