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Concrete Moisture Basics

Concrete floor moisture is one of the most researched and documented issues that affect modern flooring systems. 

The increase in flooring failures can be contributed to the use of low permeable floors, floors using recycled content and the continued reduction in VOC chemical components used in floor primers and adhesives, the rapid speed of construction and weather conditions during the construction process which prevents proper drying conditions for newly poured concrete.    

New Construction Projects

As a precaution most contractors and project teams focus on concrete moisture testing to prevent their exposure of floor moisture issues on new construction projects.  The construction team relies heavily on the concrete testing results and the personnel performing the testing to provide the information for making an informative decision on how to proceed with a flooring installation.  In most cases, the team is informed just prior to the moisture testing process that the site needs to be conditioned.  This means windows, doors, roofing, all spaces weatherproofed and the HVAC system fully operational and balanced to create ideal conditions for testing the concrete. 

Since most sites do not have an operating HVAC system until AFTER the floors are installed the information to the construction team is invalid and requires a drastic decision to be formed on how to proceed with the flooring installation process and how to maintain the construction schedule.

In recent years construction teams have overcome site conditions, construction schedules and the limitations of HVAC operation by integrating a Synthetics International treatment technology.  The treatment technologies are designed to overcome site conditions by using a rate of application to restrict the highest level of concrete relative humidity at 100% RH per ASTM F2170.  This allows concrete moisture levels to become compliant within hours of treatment application and provides an ideal bonding surface for all flooring products.  Not to mention the elimination of last minute change orders and the extension of time required to install a new concrete moisture treatment scope. 

Renovation Projects

Always a topic of discussion is the use of a moisture treatment on existing concrete floor slabs.  Old concrete slab on grade floors commonly have a missing or a non-functioning under slab vapor barrier.  This increases the possibility of ground sources of moisture just below the slab and can produce high concrete testing results.     

Construction teams are overly surprised when concrete test results are excessive and the floor cannot be installed as scheduled.  The team is then educated on the lack of an under slab vapor barrier or a ground source of moisture is preventing the new flooring products from being installed.  This continued dampness can also be a major issue for new interiors in the form of mold, mildew or other forms of damage. 

As a precaution, Synthetics International recommends using the in-concrete relative humidity testing method (ASTM F2170) to assist in determining if the vapor barrier is no longer functioning at the start of the renovation process.  This test method seems to provide a greater sensitivity to dampness from below and can provide rapid information for proper decision making. 

Floor slabs that are excessive may be sealed with a Synthetics International two-component liquid applied treatment.  These systems are designed to penetrate the concrete, cracks and joints to form a moisture compliant surface in just hours after application.   

For more information on product selection or concrete testing, please email us at