I’m quickly approaching seven years working in and around indoor sports flooring with Advantage Sport USA. Seven years of projects of all shapes and sizes ranging from 250 square foot residential basements to 30,000 square foot college field houses. Seven years of existing conditions, renovations, rehabilitations and new construction and the one constant that rears its ugly head on almost each job are the environmental conditions,including concrete moisture vapor emissions.
There are more than a few instances that can lead to high moisture in a concrete slab. Whether it is lack of a quality vapor barrier (or lack of one entirely), a fast track installation with insufficient time for the concrete to dry, an inoperable HVAC system (or again the lack of one altogether) or a plethora of other events. No matter the occurrence, it all equates to the same headaches after the fact. Normally fingers are pointed, voices are raised, materials are ripped out and unnecessary time and money is spent to potentially replace flooring that perhaps should have never been installed to begin with. Industry-speak may call it “flooring failure” but most of the time the flooring is performing exactly as it is supposed to. The adhesive on the other hand, may be completely failing.
As the built environment strives to become “greener”, VOCs have been lowered in flooring adhesives in order to make them compatible with indoor regulations. As the adhesive industry has moved towards water based and acrylic based solutions, they have become much more susceptible to concrete moisture vapor emissions. Even though the norm in the industry has raised from 3 lbs of moisture to 5 lbs, as per ASTM F1869-11 (Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride), that limit can take substantial time to achieve.
Speaking of norms in the industry, growing acceptance has moved away from calcium chloride testing (a snapshot of what is happening on the slab) to relative humidity (RH) testing (what is going on inside the slab). Testing as per ASTM F2170-11 Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes has become easier and easier with recently developed equipment, including testing probes that can be left in the slab. Even the Maple Flooring Manufacturers Association (MFMA) has gone from not accepting RH testing to ONLY accepting RH testing previous to the installation of wood gym floor. Visit the MFMA website for more information.
There are multiple solutions on the market. The cheapest is normally waiting for the concrete to dry. Abrading the top layer of the slab can help speed us this process, however most floor coverings require a smooth, steel trowel finish for installation, so the abrading would have to be covered with a Portland-based cement. Costlier solutions can include topical moisture mitigation systems and depending on the city you are working out of can be extremely pricey. Some flooring manufacturers offer solutions such as on slab moisture barriers or are moving to adhesive free installations or adhesives that allow a very high rate of MVER.
The one true method to ensure a proper floor installation is information. You need to know your flooring, know your adhesive, know your thresholds of moisture vapor emissions, know your moisture testing, testing companies and protocols, know your installer, know your time constraints, know your materials. There is no tried and true answer or solution when it comes to concrete moisture. Moisture is always present in concrete slabs and by accepting it is there and how you can live with it could be your best bet.
Take an hour of your time and join the CSI Specifying Practice Group Meeting this Thursday (December 6) from 3-4pm ET as David Stutzman, CSI, CCS, AIA, SCIP, LEED AP and Louis Medcalf, FCSI, CCS lead a CSI discussion on “Slab Floor Moisture.”
Should you not be able to attend the webinar, you can join in on a tweetchat by using the hashtag #CSISPG, which is where you’ll find me @EricDLussier