Concrete Moisture Vapor

Controlling Concrete Moisture Vapor

Moisture in concrete comes from concrete upwards through it in the form of concrete moisture vapor. Due to laws of physics, concrete moisture vapor will move upward through concrete as relative humidity. Sources of moisture can be in or below the concrete. Moisture in the concrete then moves as vapor to the surface through concrete capillaries, where it can then affect floor coverings. When the moisture vapor is traveling through the slab it is in a vapor form so it is in a gas state. When this moisture vapor is stopped by flooring it then becomes trapped between the slab and the flooring creating a damaging chemical like liquid solution. When trapped this solution dissolves flooring adhesives, can mold, smell, and even create bubbles filled with the solution within the flooring. Flooring manufactures do not warrant for this. This is why it’s always important to test your slab for concrete moisture vapor before a flooring install using proper RH Testing methods.


After testing in many cases the concrete moisture vapor or RH readings, are higher than allowed for the floor covering, and adhesive. The concrete slab must then be prepared to accept a moisture barrier. A liquid coating would then be applied to the concrete to stop it or reduce it to a non damaging rate. Before applying the liquid coating, you need to make sure the concrete slab is structurally sound, dry, clean, and free from contaminants that prevent a good bond. The concrete slab needs to be at least seven days old.

Call Tabberer's Resurfacing Inc. and we can evaluate your slab for you. We will then recommend proper planning, testing, and recommend products that will fix the issue, and provide long term manufactures warranties against concrete moisture failure.

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