The problem with this, as many have found, is that any plywood, 2x4s or any other type of wood absorbs water. This can lead to mold and mildew issues and rotting floorboards.
Fixing a wet plywood floor in the basement
If a plywood floor is wicking water up from underneath and causing issues there are three things that are needed to fix this:
Step 1: Remove the floor
Step 2: Identify the moisture issue
Step 3: Repair the moisture issue
Step 4: Decide on what you’d like to do for the floor.
Having an uneven floor temporarily outweighs any Mold or Water damage that could be generated from leaving the Plywood down.
Controlling the leak and moisture problem will not only keep this from happening again, but it will protect what is left of the finished space.
After that stage is complete you can move onto replacing the floor. The first step is adding a Sub Floor -
Addressing future flooring with a Sub Floor
Many flooring products only work with sub-flooring, or a floor that’s designed to be installed underneath the floor that you will see. It acts to separate the finished flooring from any moisture that might come into contact with it. (A carpet pad is a basic example of this, however a real sub-floor will be solid and not able to absorb moisture or other liquids.)
Products from Grate Products LLC, like WarmShield and FloorShield, have been used by Pioneer Home Basement Finishing and Pioneer Basement for years with great success. Carpets, wood flooring, and laminate flooring have all been installed and protected by the simple introduction of an in-organic sub floor.
Related Reading and Links
Plywood Floors in Crawlspace or tiny basements - Discussion on the Pioneer Forums
Read about the Top 6 Basement Mistakes that contractors and homeowners make.
Ask Jacob A question Directly on Pioneer Basement's Help Forums!