Moisture can be a major factor in the floor covering failure, whether it be on a concrete slab, suspended subfloor, on, below, or above grade. Moisture levels in excess of guidelines (usually dictated by the manufacturer on specific products) can result in costly product failure, and damage not covered under warranties if they exceed specific guidelines. Some floor covering products are more susceptible to moisture than others. The most common causes for moisture-related flooring problems are excess RH (relative humidity), excess MVER (moisture vapor emissions rate), Alkalinity, Interior Leaks, Exterior Penetration, Hydro Static Pressure, and Osmosis.
There are a few ways to test for moisture content in existing floor covering using RH meters, Non-Invasive Meters, and pin or probe-type meters, They can give indications of excess moisture and cause for related problems.
There are also two methods to test concrete for moisture: The anhydrous calcium chloride test, described in ASTM F-1869-10, Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride measures the moisture vapor emission rate (MVER) of the slab. The relative humidity probe, described in ASTM F- 2170-11, Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs using in-situ probes measures the internal relative humidity of the slab.
The Calcium Chloride test determines a portion of the free moisture near the surface of a slab, generally, the upper 1/2 to ¾ in., or (12 to 20 mm) providing no information about the moisture conditions deeper in the slab, though widely accepted by most U.S. floor covering manufacturers.
Relative humidity (RH) testing is determined by in-situ probes installed deep in the slab. Unlike the MVER test which looks at the top ½ to ¾” of the slab, the ASTM F 2170-11 standard recommends that RH measurements be taken at 40% of the slab depth. For example, on a 4” thick slab, the probes would need to be placed at a depth of approximately 1.5”. RH testing is a significant tool in predicting potential concrete moisture-related floor covering failures that can lead to costly repairs and litigation. It stands to reason that if a slab contains a high level of relative humidity within the slab, the moisture will migrate to the warmest, driest area of that slab; if that is the surface of the slab then the moisture will migrate upward.
Making sure your subfloors are within tolerance to accept new flooring is of the utmost importance. This can save you thousands of dollars in the long run and help minimize problems. Floor Covering is one of the largest and most expensive purchases you will make in your life. Making sure your environment is acceptable and suitable, and the product(s) you choose prior to making a purchase is essential to meeting your expectations and long term sustainability in the years to come.
The Carpet and Rug Institute, which is a major component in establishing Industry Standard Guidelines for residential and commercial carpet installation states:
CRI 105-6.0 Residential Carpet Installation Guidelines/ General Requirements/ Testing :
“Most residential stretch-in installations do not require moisture testing. Before direct glue-down, double-glue down, and free-floating carpet tile systems, the owner or general contractor, or their designated testing agent, is required to submit to the flooring contractor a written report on the moisture and alkalinity conditions of the concrete substrates. Refer to the manufacturer’s written instructions for guidelines regarding allowable moisture and pH limits for their products. The Moisture Vapor Emission Rate, Relative Humidity & Alkalinity testing must be performed to give an accurate assessment of the concrete condition and the test results/data of each test shall be within acceptable limits. Proper testing is essential for a successful installation and any deviation from these industry-accepted test methods often results in an installation failure and may void manufacturers’ warranties”.
CRI 104-6.0 Commercial Carpet Installation Guidelines/ General Requirements/ Testing states: “Refer to the manufacturer’s written instructions for guidelines regarding allowable moisture and pH limits for their products. The Moisture Vapor Emission Rate, Relative Humidity & Alkalinity testing must be performed to give an accurate assessment of the concrete condition and the test results/data of each test shall be within acceptable limits. Before direct glue-down, double-glue down, free-floating carpet tile systems, and some stretch-in installations, the owner or general contractor, or their designated testing agent, is required to submit to the flooring contractor a written report on the moisture and alkalinity conditions of the concrete substrates. Proper testing is essential for a successful installation and any deviation from these industry-accepted test methods often results in an installation failure and may void manufacturers’ warranties”.
Both CRI 104-6.0 and 105-6.0 state: “NOTE: It is recommended that qualified independent third-party testing agencies be used for determining moisture and alkalinity conditions of a concrete slab. Testing by an independent third-party specialist to determine installation suitability is a prudent and necessary safeguard for general contractors, owners, architects, flooring product providers, and installation contractors to reduce the risk of concrete slab moisture-related flooring problems. As a minimum, testing agencies or individuals are required to demonstrate verifiable experience in concrete moisture testing or be certified by a recognized organization”.
The National Wood Flooring Association (NWFA) guidelines state:
3.1: Moisture Testing for Wood Flooring and Wood subfloors; ” Determining moisture content is an essential part of quality control within the flooring installation process”.
3.2: Moisture Testing for Concrete Slabs; “Note: All tests give a result at the time the test is done and in general, give you the ability to start or not start a job. These tests do not give a permanent condition of your substrate, but merely an “at the time the test was performed” indication”.
3.2B-4: ” If the moisture meters indicate the presence of excessive moisture, as per wood flooring or meter manufacturer’s recommendations, further testing is required using relative-humidity testing (ASTM 2170), calcium chloride testing (ASTM F1869), or calcium carbide testing (ASTM D4944 and MilSpec CRD-C154-77).
Most Hard Surface Manufacturers, including Laminate, Luxury Vinyl Plank, Luxury Vinyl Tile, Resilient, and most all hard surface products, require subfloor and concrete moisture testing in addition to verifiable product acclimation that coincides with the substrate moisture content.