Finish TradesQuestion 235 of 700

The in-situ relative humidity (RH) probe test (per ASTM F2170) is another way to check a concrete slab before flooring. Many resilient flooring manufacturers set an acceptable internal RH limit at about:

a.75 to 80 percent
b.10 to 15 percent
c.50 percent exactly, never higher
d.99 percent

Explanation

In-situ RH probes commonly must read at or below roughly 75 to 80 percent (per the specific product) for resilient flooring to be installed safely. Ten to 15 percent is unrealistically dry, a flat 50 percent cap is stricter than most products require, and 99 percent is far too wet.

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