The test method involving taping down a plastic sheet is not a quantitative test and is not considered an acceptable test method by any major flooring manufacturer. A surface moisture meter does not give any indication of free moisture in the concrete slab and are only used for comparative relative readings and they do not to give any sort of accurate moisture reading. Both of these methods can provide you false negatives resulting in a failed flooring system.

There is only one test method that is recognized as being accurate by basically every major resilient flooring manufacturer which is ASTM F2170-02 Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In-Situ Probes.

The test method ASTM F1869-04 Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride has been found to not always be accurate and is becoming disallowed by many manufactures due this type of test many times producing inaccurate data.

The test method ASTM F2420-05 Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and Insulated Hood is a good test but it's mostly used in forensic work and not considered as accurate as ASTM F2170 so it's not specified by many flooring manufactures.

Posted By Summers on 08/24/2009 6:54 AM
ajanne999, In the interest of affording you a "Real Answer" to your "Anybody know who is right?" question; points for you to consider: (1)There are three test methods for concrete slabs that MAY be accepted by Tarkett. ASTM F-1869, F-2170 and F-2420, none of which involve use of a surface moisture meter or a piece of plastic taped to a floor! (2)An "Effective Vapor Retarder" doesn't sound feasable for a slab poured in 1911! (3)Most Flooring manufacturers will approve of the F-2170 test done by a certified test provider, demonstrating an internal humidity of 75% or less. (4)Concrete in general is a very complex, thermodynamically unstable material, especially, when involving these types of issues. Your slab is subject to a host of events and environments that it has been subjected to since 1911. Confirm with Tarkett what test regimen they Will accept and Warrant, get that statement in writing from the COMPANY and Cross Your Fingers! So, your answer is somewhere between No & Maybe!

Clarification:

Based on the original post, the house was built in 1911 but a NEW subfloor is being installed so it is imperative that an "effective vapor retarder" be installed in accordance to ASTM, ACI, or the Canadian equivalent standards.