What Is Moisture Vapor Transmission?


The pictures posted are a classic example of what happens when moisture seeps through your slab. Moisture vapor transmission is when water penetrates through the concrete slab.

It becomes a major concern when concrete is used on building projects where the concrete will be covered with a finished material. This would include slab foundations with interior flooring, basement or interior walls with drywall, and concrete ceilings where a finished material will be directly affixed to the concrete.


Moisture Vapor Control Photo Credit from Vodapruf.com/

The truth is that even the slightest amount of moisture or water vapor can compromise the concrete floor and possibly ruin the installation. Whether the slab is new or old, moisture can still find a way to penetrate through if the right materials are not used.

The trouble in these situations is that water vapor evaporating out of the concrete is unable to escape the finished material leaving moisture trapped beneath the surface of the finished material, which will cause problems such as bubbles in the finish, deformed flooring, or gold or brown spots on the concrete surface.

Concrete: Sand, Gravel, WATER, and Cement

Water Vapor Photo Credit from http://vodapruf.com

Water Vapor Photo Credit from http://vodapruf.com

Concrete is the combination of sand, gravel, water, and cement. In their separate parts, none of these ingredients would make for a very good floor, wall, or ceiling. Once combined though, we get the concrete that we all have come to know and love as a building material. However, the water in this now solid concrete will eventually evaporate.

Even in a seemingly solid object that we have created for our own purposes, it will still convert itself into a gas and try to escape. In its liquid form, it has little chance of escaping from the concrete. As a gas, it has a better chance of escaping, and it will. In fact, it does. The water, now a gas evading the concrete will cause damage and erosion to the flooring as mentioned above.

Trapping the Gas
There are a few ways we go about controlling moisture transmission. By installing the proper moisture control flooring and moisture vapor barriers using industrial and commercial epoxy urethane coatings; the vapor barriers we use to control moisture transmission trap water vapor to keep it from reaching material that can be damaged by long-term exposure to moisture.

While protecting the external materials is one benefit we gain from a vapor barrier, there is still another. We also prolong the lifespan of the concrete. We keep the critical ingredient trapped, so the concrete doesn’t fall apart and the surface treatments remain in beautiful condition for a much longer duration.

Why choose a Moisture Vapor Mitigating (MVT) flooring over an inferior permeable flooring?

First the Permeable: The Problem

The permeable floor system allows water to freely evaporate out of the concrete causing it to become brittle. This is when we see tiles disconnecting, paints bubbling, cracks and general erosion. It also allows moisture or other chemically laced liquids to penetrate the slab, from the outer surface, which can accelerate the deterioration process. This results in unfavorable conditions caused by the floor surfaces. Meaning unpleasant looking floors in your work areas to unsafe conditions that lead to injury or unproductivity

Moisture Vapor Mitigating Flooring: The Solution

As mentioned previously, when the proper moisture control flooring is installed with the right industrial and commercial coatings the original water that was in the slab during its creation is now being trapped by the impermeable membrane. And the erosive external forces are being kept out by the impermeable membrane. The result is flooring that lasts longer because it is being protected by a vapor barrier which minimizes erosion, peeling, and hazards to your flooring.

So far, we have only mentioned vapor barriers that are applied between a slab and a finished material, but there are others. In some situations, an epoxy floor paint is used as both a sealant and a vapor barrier for a concrete slab. This specially formulated paint is applied directly to a finished slab to create an impermeable protective layer. The epoxy keeps the original moisture in while keeping the erosive moisture out.

What to do Next

Moisture problems in or beneath a concrete slab is a growing problem. Our goal is to help you reduce bond failures caused by moisture vapor transmission by controlling or lessening the rate of moisture transmission in the slab. We can successfully do this by installing impermeable systems on these surfaces.

If you have any additional questions regarding moisture-vapor transmission or permeable films or any other flooring items, please use the form on our contact page.

Concrete Testing Methods – ASTM Standards