What Are the Dangers of Laying Carpet on Concrete With Moisture?

Moisture on Concrete Floors

• Several factors affect concrete and its ability to stay dry. It is a porous substance to begin with, which allows any moisture in the soil underneath to seep through -- known as wicking -- to the surface. Concrete floors tend to be cooler than the soil underneath as well, which causes condensation and wicking to occur. Of course, concrete is mixed with water to begin with, and the curing process takes several weeks at least until the concrete is totally dry. All of these factors will cause moisture to collect on the surface of concrete floors.

How Moisture Affects Carpet

• A wet carpet is more than a housekeeping problem. Continual moisture under a carpet can lead to serious health problems. Mold and mildew are just two of the biological pollutants that are a constant threat in any moist condition, and carpets are especially troubling because they hold moisture longer. The presence of mold and mildew contribute to and aggravate many respiratory problems including allergies and asthma. A wet carpet can't be picked up and washed like area rugs can, so carpet on a concrete floor becomes an even bigger issue for homeowners.

What To Do

• Controlling the conditions that cause moisture on concrete floors is the best approach to take. Circulation and the use of de-humidifiers in rooms where concrete floors have excessive moisture is the easiest and least expensive step to take. You may consider sealing the concrete floors with a vapor barrier or even adding an additional floor covering, such as wood, on top of the vapor barrier. These are more expensive options, but they will greatly reduce excessive moisture so that you will be able to safely use carpet over the concrete floors.

Original Construction Remedies

• Moisture barriers such as gravel and thick plastic sheeting can be installed on the soil before concrete floors are poured. Efficient drainage systems installed around the foundation also help to keep groundwater from wicking through concrete floors. Insulating the sub floor and using high quality insulating concrete to begin with are additional steps the builder can take to prevent excessive moisture on concrete floors.