Who Says Rapid Rh Reads High?

[Ernesto]

Tested a slab on grade, almost in the wash, probably one of the lowest points in the area as far as water tables run. Got readings of 67 to 70% rh @ 70 to 72 F. Getting tons of rain down here and water puddles in the yard. Home is 15 years old at least so doubt there is a vapor barrier underneath. I was certain I would get at least a 95% rh. Goes to show you never know. I be gluing some engineered hardwood down with Sika T-21.

Didja know Sika has no numbers for either 1869 or 2170?