Hey all,

I’m about to install wide plank (8″) heart pine in my new home. It’s going down on the ground level above two zones.
          1) 1990’s addition with an unfinished, poured concrete basement and plywood subfloor.
          2) Original 1950’s build above a crawlspace (cinderblock foundation) and narrow plank subfloor (almost like lath)

I live in upstate New York in a fairly moist valley with a creek close-by (5A climate zone)

My question is about moisture barriers – specifically above the unfinished basement. I’ve read that I shouldn’t use a moisture barrier on a plywood subfloor because the moisture can get sandwiched and rot the subfloor. But the basement has a fairly high RH and I don’t want my planks to cup. 

Any advice on underlayment/vapor retarder/ moisture barrier would be greatly appreciated.