Fredd Wright wrote in
:

I have a crawlspace in the basement that has a dirt floor right now.
I'd like to lay some sheets of 4x8 plywood (or other material) on it
to make a surface suitable for crawling on or putting things on. It
will lay right on top of dirt. It doesn't have to look good as it's
in a crawlspace in an unfinished basement. I't won't be exposed to
rain but there will be some moisture coming up through the dirt.

Your plywood will rot, even if bugs don't eat it first.

If you have lots of money, Markem's suggestion of PVC boards
would work. Otherwise, you're probably better off just
leaving it alone.

John