Can there be moisture problems with LVT floor coverings?
The answer is yes! See photo showing an LVT floor which shows cupping.
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I received an Email from a customer who had installed an LVT floor directly over concrete and he wanted to buy a pin meter from us to measure the moisture in the concrete slab underneath the LVT floor. He had issues with the LVT floor buckling and he sent this photo to demonstrate the problem. He is an amateur and he installed the floor as a favor to a friend. His neighbor a general contractor helped with the installation. Here is what he stated in an Email he sent me after the floor had failed: He contacted the company where he bought the flooring from, and they sent a representative. The rep said he had never seen anything like it. They pulled off several base boards to show they had the proper clearance. The company he bought the floor from paid for an independent inspector to come out. They based the denial of the claim on too much moisture in the concrete. The inspector placed a pinless meter (not from Lignomat) on top of the LVT, set the meter to a drywall setting and the meter indicated 96-100% (comparative scale). From those measured values the inspector concluded that the floor buckled, because the moisture content in the concrete was over 75%. This is what the customer wrote in his email. |
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From my point of view, there are many problems with this inspection and the conclusion. Let’s start with the most obvious one. The value indicated by the pinless meter is not a percent measurement. The inspector should know better than talk about a 75% moisture value as a limit for concrete moisture measured with a pinless meter through an LVT floor.
In order to give some advice to this distraught customer, I asked about the installation instructions and what the manufacturer requires as concrete moisture testing before installation. That information should shed some light on this value of 75% and also how this value is measured.
The customer did not have the instructions anymore, but he stated it said under 75%. So, I looked for an installation manual from a prestigious LVT flooring manufacturer and found the following:
All concrete slabs must be checked for moisture before installing material. Moisture emissions from sub floor cannot exceed 3 lbs. per 1,000 sq. ft. per 24 hours as measured with the Calcium Chloride test or in excess of 75% in situ relative humidity. Responsibility for determining, if the concrete is dry enough for installation of the flooring lies with the owner and installer.
This is exactly what an instruction manual should look like. It gives the correct guidelines by setting a permissible range for a specific test method to determine whether or not a floor can be installed. Installers and inspectors can follow those guidelines.
75%? Following the instructions in the manual, a 75% permissible moisture range is not for a pinless moisture meter test, but it is the permissible range for the in-situ probe test. Could that inspector be so confused about how to test the moisture in a concrete slab?
The in-situ probe test determines the relative humidity in concrete floor slabs. The test method is used as a quantitative determination (not qualitative or comparative) of relative humidity in concrete slabs as described in the ASTM standard F 2170.
It is a test which requires drilling a hole in the concrete floor, setting a sleeve, inserting a relative humidity probe.
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See photo, RH BluePeg probe from Lignomat is inserted into the sleeve to measure evaporation from slab. After acclimation the relative humidity in the small area at the bottom of the sleeve is measured with a relative humidity measuring device such as the Ligno-DuoTec BW, a pinless and RH moisture meter. Relative humidity values can go up to 99.9%. The percent value from the in-situ probe test is a relative humidity percentage of air. It is not a concrete moisture percentage. |
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The manufacturer states in the installation manual, that the moisture emission from the concrete slab should not exceed 75%. However, if the inspector uses that moisture value, he should have at least used the test method described in the manufacturers instruction manual to prove his point. There is no pin less moisture meter, nor a moisture range mentioned.
To help the customer out, I recommended to either get an inspection service which does in-situ probe testing or to buy an in-situ probe test kit such as the BW-KS package from Lignomat. I did not sell him a pin moisture meter to measure the moisture in the concrete slab, even though that still is a moisture measuring method used for concrete slabs. But since the method is not approved by the floor manufacturer and not mentioned in the manufacturer’s installation manual, any moisture measurements done with a pin meter would not have been relevant to argue about a warranty claim.
From Floor Covering News by Grete Heimerdinger, Lignomat
→ Click to read more about Merits of the In-Situ Probe Method Recommended?
→ Click to watch a video demonstrating Lignomat’s ASTM F2170 RH in-situ probe test
→ Click to read more about Importance of Measuring Concrete Moisture with In-Situ Probe Test
→ Click to read more about Lignomat’s Unique Design for Taking Measurements Using ASTM F-2170