I have an 50-year old home. The flooring structure is as follows.... 3/4" subfloor planks on top of the joists. Then a layer of moisture barrier (some sort of thick heavy black roofing material). 1x2's on top of the paper, running directly over the joists... (are these what you call "screeds" or "sleeper studs"?)... and finally, a layer of 5/8" underlayment.

When I go to install my wood flooring on top of the underlayment, do I need to install yet another layer of moisture barrier on top of the plywood underlayment or am I good to go with the layer that is already there underneath the underlayment?

I'm thinking I shouldn't need to worry about moisture transfer from the underlayment to the new flooring, only because the underlayment is 50 years old and if I had to guess, I'd say it's probably **pretty well** acclimated by now.

Also, if this matters or not, there is no crawl space... I have a full finished basement and it is pretty dry down there.