Epoxy coatings are a topical option, and usually consist of two parts that are mixed together immediately prior to application. They are primarily used to protect concrete from chemicals and abrasions; however, a special category of epoxy coatings called moisture reducing epoxies are able to resist vapor transmission and moisture coming up through a concrete slab or foundation.
Moisture reducing epoxies are an even more effective and flexible option, as they are manufactured to withstand moist conditions. They are not, in fact, chemically or physically sensitive to certain quantities of moisture. This means that you can actually apply moisture reducing epoxies to surfaces that are not entirely dry, making it a great option for a perennially damp or moist slab of concrete.
In order to determine how much moisture is present it is best to perform a calcium chloride test to determine the moisture vapor emission rate (MVER) of a concrete slab. To perform the test, a small amount of calcium chloride (salt) is placed under plastic on a clean piece of concrete. The calcium chloride (salt) absorbs the moisture coming from the concrete slab over a period of about 72 hours. The weight gain of the calcium chloride is then measured and the moisture vapor emission rate MVER is calculated. If a high amount of moisture is present in the concrete (over 3 lb according to a calcium chloride test) it is best to use a moisture vapor barrier coating.
A moisture reducing epoxy like the Vapor-Tek 440 will improve the water resistance of your concrete up to 20lbs/24hr/1000ft allowing for the application of wood flooring, tile or any other floor covering. A calcium chloride test can be performed prior to installing the coating to make sure that the coating will be able to withstand the amount of moisture in a concrete slab. The Vapor-Tek 440 is one of the best moisture vapor barrier coating products on the market to reduce moisture vapor transmission to levels that are acceptable for the installation of flooring. The high performance and high level of protection make this concrete coating the ideal moisture reducing epoxy.
The Vapor-Tek 440 can be used as a primer before applying a concrete coating such as the Urethane 645.