Since sports floors represent a significant investment, installers will ideally always specify stable and secure moisture content (MC) in the concrete subfloor. Otherwise, the water content in concrete can risk the entire floor. If installers pay little heed to MC in the subfloor, athletes will surely pay heed to the devastating effects of trapped moisture content.
Relative humidity (RH) is the key to determining stable MC in concrete subfloors.
Multi-Purpose Sports Floors
Increasingly, sports floors are tasked with multi-purpose versatility. This is a primary reason why synthetic floors, such as polyvinyl chloride (PVC) and poured urethane, have come to challenge maple wood for sporting competition.
Let’s consider the costs based on the life cycle of the sports floor. A study conducted by the Maple Flooring Manufacturers Association (MFMA) found that synthetic surfaces carry higher life-cycle costs than maple, with poured urethane the most expensive of the options studied. Synthetic flooring may be able to take a beating in a multi-purpose sports complex, but installers pay for it over the life of the floor.
The Concrete Subfloor Factor
So, how does a concrete subfloor figure into it? Simple. Excess moisture content jeopardizes any sports floor covering.
The industry has grappled with concrete floor moisture test methodology for decades. In the past, contractors used the anhydrous calcium chloride test for testing surface moisture with mixed results. Many concrete floors failed because calcium chloride (CaCl) does not account for internal slab moisture content. In the mid to late 1990s, scientists started conducting extensive research to see if there was a way to test at a specific depth in the concrete, and be able to utilize that information to better predict what surface moisture conditions would be like once a finished floor product was installed. Thus, relative humidity testing was born, and the industry has grown to embrace it. RH testing tells you what the moisture level will be at the surface before you spend the time and money on a flooring installation, rather than what conditions happen to be at a single point in time, which is all a calcium chloride test can report.
RH Testing
Because a drying concrete slab has a gradient trend to its moisture content, the amount of water vapor at the surface is no indicator of the overall presence of moisture content in the slab. Keeping that fact in mind, any surface-limited test method is bound to give a false sense that the slab has reached installation conditions for the flooring specified in the building design. The true value of RH testing is its use of in situ probes, sensors installed within the concrete slab at a depth that has been proven to best represent the overall final RH level if the slab were to be sealed at that point in time.
It’s a test method that stands up to the time realities of a floor meant to last for up to four decades of hard-pounding, athlete-driven use.
Industry standard-makers recognize relative humidity as a credible moisture assessment method. ASTM International has established RH testing through ASTM F2170 as a standard moisture content test procedure. In addition, the MFMA has also adopted RH testing as the recommended test method for sports floors.
RH testing is a credible investment in concrete subfloors when installing sports floor coverings. It’s safer to ensure accurate moisture content when a lifetime of competition is on the line.
