I've had a recent rash of contracts where installers are removing successful floors to install new modern flooring and these installers find the old slabs are quite wet.

They are lucky if they do their testing BEFORE they install the new flooring, but sometimes these installers are shocked to receive failure complaints only a few weeks after installation.

Old flooring sometimes breathes better than what we install today, and the adhesives of the past are no longer allowed for modern installations. A slab that held a floor previously may not be suitable for new products. And those old 6 mil vapor retarders break down over time, so I advise testing on any slab where the pedigree is not known, or the slab is over 10 years old. Even then, I always put in a couple RH probes for peace of mind.

Better to catch that moisture before the installation and deal with it up front!

And so goes the theory of relativity that well...that if the wood floorover there is Ok, we're safe to throw this one down