Can Laminate Flooring Be Installed Over Concrete?

Leveling the Concrete Floor

• Concrete floors must be level, with no dips or chips. Use a patching compound to fill in chips and level dips in the concrete. Self-leveling compounds can be used in place of patching compound, but they do require a little more work. The compound needs at least 48 hours to dry. In addition, new concrete floors must cure for at least 60 days before you can install laminate flooring over them.

Moisture Barrier

• Installing laminate over a concrete floor that is in a basement or another room below the ground surface will need a moisture barrier. The soil below the concrete floor will cause humidity to accumulate in the concrete because of the large amount of water in the soil. A moisture barrier will prevent humidity and moisture from reaching the laminate flooring, which will eliminate the possibility of mold and mildew growing between the laminate and concrete. The moisture content of the concrete must be lower than 2.5 percent, but if you have a heated floor, the moisture content must be lower than 1.5 percent, and the temperature cannot be higher than 85 degrees Fahrenheit, according to Armstrong Flooring.

Testing the Moisture Level

• Place four or five sheets of polyethylene that measure 3 feet by 3 feet on the concrete floor. Tape the sections together so no air can get under the sheets. Tape the edges to the concrete. Wait 24 hours before checking for moisture under the sheeting. If you see moisture or the concrete looks dark, you may have too much moisture from the floor. A calcium chloride test is needed to test the actual moisture level in the concrete. Your local flooring dealer can recommend someone to conduct this test.

Underlayment

• Laminate comes with or without the underlayment attached. Some floor products come with a moisture barrier underlayment that is attached or separate from the laminate flooring. When using polyethylene sheeting for the moisture barrier, you do not need to use laminate with an attached moisture barrier underlayment. If you are installing the laminate on a concrete floor and you are not using a moisture barrier such as a polyethylene underlayment, you must use laminate with the moisture barrier underlayment attached. If the underlayment you are using isn't rated as a moisture barrier, you need to use the polyethylene film on the floor before laying the underlayment or laminate with the attached underlayment.