Controlling moisture vapor transmission (MVT) is critical to the long-term durability of any slab-on-grade flooring. When moisture is present in concrete, it not only can cause blistering and peeling of a floor coating, but it can also prevent proper adherence to the slab. The end result could require a complete removal of the current system and the installation of a new floor coating system, which would include a moisture vapor barrier product.
The source of the moisture can come from the soil beneath the slab, especially if your facility is in an area in which the ground stays damp most of the year. One reason why moisture can seep up to the surface of the concrete is because a moisture protector beneath the slab was either omitted or installed incorrectly during the construction phase.
Moisture can also come from the concrete itself. This can occur because water is a major component of the mixing process in concrete, and it is a porous substance which absorbs water. If it was not left to cure for a sufficiently long period of time—possibly, several months to a year, with a recommended minimum cure time of 28 days—the moisture vapor can be transmitted to the surface. This cure time, however, is unrealistic for the production demands of many facilities.
Whatever the source, MVT can be both problematic and expensive and, in these circumstances, the value of an ounce of prevention definitely exceeds the value of a pound of cure.
