More Info: Laminate flooring can be installed over concrete as long as certain criteria are met that include level and fully cured concrete, a moisture level below 4.5%, the absence of a floor drain or sump pump, and an added vapor barrier.
Perform a Moisture Test
If you are installing your laminate flooring over the concrete in a basement, you must ensure that the moisture present is at acceptable levels. You can use either a moisture meter, or a calcium chloride test. According to Pergo, an acceptable moisture level for installing their laminate flooring is a moisture reading no higher than 4.5%.
The test should be performed at different times of year to ensure that the moisture content is not excessive during any one season.
You should not install laminate flooring if your concrete subfloor has a floor drain or a sump pump.
Acclimate Your Flooring
Prior to installation, it is important that you acclimate your flooring to the surrounding conditions for 2-4 days. To acclimate you flooring, remove it from the carton and lay it a minimum of two feet from the wall in the room in which it will be installed. The temperature should be at least 65°F with a relative humidity of 30-90%
The Concrete Must Be Cured
Do not install new laminate flooring over new concrete. New concrete can take several months to fully dry and cease to release moisture. Wait a minimum of 60 days.
The Concrete Must Be Level
The concrete subfloor upon which you are installing your laminate flooring must be level. Any areas that are either higher or lower than 3/16” of an inch within a 10’ radius must be leveled by either filling in or grinding down.
Install a Foam Layer
This foam layer will provide cushion against the hard concrete. This should be installed in overlapping layers and secured well.
Add a Vapor Barrier
Because basements tend to retain moisture, you need to use a vapor barrier along with the foam underlayment. You should purchase a non-recycled 6-ml. polyethylene film to use as a vapor barrier, overlapping the edges. Vapor barriers are required over any concrete subfloor even if the concrete is currently covered with another type of flooring such as vinyl or tile.