Before installing a beautiful new floor, do you know the moisture vapor emission rate of the concrete substrate that you are about to install that floor on? Do you also know the moisture sensitivity of the floor covering and the installation materials? If not, you need to step back for a moment and find answers to these questions. Many decorative floor coverings and their installation materials are sensitive to excessive moisture. Moisture can cause floor coverings to swell or blister and wood flooring may even buckle. The adhesives used to secure the flooring to the concrete substrate can dissolve and allow the floor covering to come loose from the substrate. Continued exposure to moisture allows mold to grow under the flooring material, which can cause discoloration of the flooring and affect the health of the building occupants.
Persistent moisture typically comes from the concrete substrate in the form of vapor. Moisture vapor is the gaseous form of water. It surrounds us every day and is measured as relative humidity in the atmosphere. It is also found in any concrete slab. Water is added to the dry concrete mix to improve mixing, pouring and placement of the concrete. Part of the mix water will bind to the cement particles in the concrete through a chemical process called hydration. The excess water not needed for hydration must leave the concrete as vapor. This is a slow process and can take as much as a month for every inch of thickness in the concrete substrate.