Adhesives and Moisture

[CC Solutions]

Thank you for posting that Ernesto, these boards have been kind of quiet this week!!

I think I can read between the lines of your post. Please remember there is no correlation between MVER and relative humidity. A perfectly dry slab that is sprinkled with water for a few seconds will have a terribly high MVER, and this can have an effect on adhesive bond.

Also true is a slab with no vapor retarder can seem very dry and have a good MVER reading, yet fail over a short period of time after moisture wicks through the slab and attacks the adhesive bond.

I'm repairing a slab soon that had great MVER readings when the floor was installed but has since failed and now has high MVER readings. The slab is on a blotter layer of sand. The RH tests were bad from the get-go, but the installer went by the MVER readings because they were within specs.

This is why manufacturers are changing their specifications to rely less on the outdated CaCl test. You just can't trust MVER tests alone.