If you really want to rot a floor though the absolute best A+ gold star method for doing so is adding a gas log fireplace with surround. I had a house a couple years ago that had moisture from the flue pooling inside the surround and under the unit. Rotted through 3/4" red oak hardwood flooring, 2 layers of 3/4" plywood, and bit off the top 4" of the 2x8 joists under the unit. Interior space was a solid sheet of black mold. That was one of those bag-the-room negative air pressure break-out-the-space-suits jobs. Six months later I was on a job where condensation off another gas log flue pooled inside a surround and got into the OSB cladding, then wicked 9' straight up. Only time I've ever seen cedar siding actually rot. We ended up having to cut the entire fireplace surround and a portion of the roof off the side of the house and rebuild it studs and all. Never a dull moment I tell ya.
> ... and the floor treatment rejects both vapor and spills.
That's a good point I didn't consider. Drying out the inner surface works well for interior vapour that gets into the enclosure, but won't handle spills, or standing water well.
Doesn't this risk any water that does end up getting in, to accumulate and cause more damage over time since there's no route for it to dry out?
I was always taught in my building science courses to put the water/air/vapour control layer inside the wall, before the insulation, so vapour can dry out from both sides.