Moisture Testing

Moisture Testing Services:

Slip Free Systems will provide testing services and a full length moisture test report, including possible causes and solutions using the calcium chloride method for $495.00 in the Houston Metro Area.


Common Testing Methods and Metering Devices

WPplasticsheetPlastic Sheet Method: This is something you can do yourself, it will not give you a numerical reading but it will confirm or deny the presence of water in your slab.

Securely tape an 18″ x 18″ square of clear plastic on all 4 sides over the concrete in an area where you suspect a moisture problem. We recommend that you test two or more areas of the slab in question for optimal results. Wait 16-24 hours. Check for condensation. If condensation is found on the underside of the plastic or on the concrete, then you have a moisture problem. It is important to note that not all tests by this method will be an effective sign of issues in your slab, this test is highly dependent on outside conditions such as rain, temperature control, humidity and other factors. In cooler temperatures (ambient/air or surface) the concrete may retain its moisture and fail to build up under the plastic. In warmer temperatures like we have here in Texas the moisture could actually shrivel up and die from heat exhaustion. So this test should be used with caution and as a general means of determining whether or not to proceed with obtaining professional help.

Calcium Chloride Test:

The Calcium Chloride Test is just a little bit more technical. This test measures the degree of water vapor emission rising out of a concrete slab over time. Contractors and architects frequently require this type of test on construction projects before moving forward with floor covering installations. Here at Slip Free we administer the test for a variety of customers. Testing by this method will provide readings, as related to lbs. (pounds) of moisture/vapor being emitted out 1,000 sq.ft. of concrete during a 24 hour period. The industry norm dictates that the moisture/vapor emission rate should not exceed 3 lbs per 1000 sq.ft.
ASTM Standards & Practices for Calcium Chloride Testing:

E-1907-97 Standard Practice for Determining Moisture-Related Acceptability of Concrete Floors to Receive Moisture-Sensitive Finishes
E-1869-03 Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Sub-floor Using Anhydrous Calcium Chloride
E-l907-97 Document describes all the major tests commonly used for concrete floor slab testing (which includes the Calcium Chloride Test)

Electronic Moisture Meters:

These meters read moisture content immediately. Detects moisture beneath the surface by measuring the resistance between two low frequency signals transmitted from conductive pads on the base of the instrument. These meters, like other testing methods are dependent on environmental conditions.
WPprobeAnother method is to drill a hole in the concrete and place a special plug in it. The probe of a humidity gauge is inserted into the plug and left to stabilize for 12 hours. RH reading is taken. The advantage of this method is that the RH measurement is not effected by sealers, curing agents, or coatings on the concrete.

Typical signs of rising moisture/vapor problems:

Excessive rising moisture being emitted from bare concrete typically exhibits itself on sealed surfaces in the form of efflorescence , which manifests itself in the appearance of little while puffy clouds that sit on your surface.

On floors where a coating has been installed signs of moisture include outgassing, blistering, pealing, loss of clarity, darkening of substrate beneath sealer, efflorescence issues, and total bond failure.

Water will transmit to the surface when there is higher vapor pressure in the concrete than in the air above the surface. This condition is more apt to occur when the air conditioning is first turned on in a new building; therefore, it is best to allow the air in the building to stabilize for a minimum of 24 hours before sealing an interior surface.


Accurate testing of all concrete surfaces, as related to rising moisture/vapors is imperative in order to assure successful outcomes as related to adhesion, clarity, appearance, and longevity of coatings. Doing so will enable you to select the proper type/formulation of sealer and/or coating in order to achieve maximum bond, cured out properties, and performance characteristics.

We offer a variety of solutions to fit your need and budget requirement depending on the magnitude of your problem.

In cases where the rising moisture/vapors being emitted are deemed to be continuous, and/or exceeds the 3 lbs per 1000 sq.ft. over 24 hour period, there are potential solutions such as: crystalline waterproofing systems that form a gel in the capillaries of the concrete as rising moisture comes in contact with them (some even able to withstand hydrostatic pressure), as well as custom formulated impregnators. These modern chemically engineered products/materials are capable of deterring, or even in certain instances preventing, rising moisture from reaching the surface.