it's 23/32" (3/4" plywood) stamped on it and labeled "underlayment" - what i'm wondering about is, there are sections of the plywood that appear to have pieces of it peeled off - and you can see red wood where the actual layer covering it peeled off.
there's no real consistency to this pattern, and there are small round sections (maybe 1" or so).. long sections (about 5-6" in length, maybe 1/2" wide), some spots in circles..... you get the idea.
these - "conditions" - for lack of a better word, are only a small percentage of the subfloor - but i'm wondering if this was a condition of the plywood that was present when it was installed, - or is it caused by other factors ?
and - is this something i should be worried about ??? (ie. possible future structural issues)
FYI, the basement is bone dry - i mean BONE dry.. (hyrgrometer measures 16% humidity right now).... however, during the summer months, the warm summer air, & cold concrete make for higher humidity (say around 60-70% on the meter).