In some cases, engineered wood flooring can be installed directly over concrete and even in below-grade applications. This is something that solid wood floors typically cannot do. However, before installation is attempted over a concrete floor or a basement slab, it is important to conduct a vapor transmission test to determine whether the level of concrete slab vapor emissions (hydrostatic pressure) is acceptable.
Excessive moisture in a concrete slab can be devastating to an engineered wood floor and can cause the plies to separate. Moisture emissions through the slab typically must not exceed 3 pounds per 1,000 square feet in 24 hours. You can test a slab yourself using a calcium chloride vapor transmission test kit sold by flooring suppliers.
A new development that makes engineered wood flooring and laminate plank flooring easier to install over concrete is a system of raised subfloor tiles. This system effectively lifts the flooring slightly above the slab, creating a space for air circulation beneath the flooring and reducing the chances of moisture damage.
Raised subfloor panels can also be used on standard floors where the condition of the subfloor is less than ideal.