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  • Obex Co

95% Relative Humidity: What Does It Mean?

Renovation and rehabilitation construction projects with existing concrete slabs are on the rise, resulting in challenging decision-points for owners, specifiers and contractors. These difficult decisions include reconciling concrete moisture control system costs against moisture-related resilient flooring failure risk.  Customers are left asking serious questions like – “Should I install an ASTM-F3010 epoxy retrofit system or substitute that system with a performance adhesive? Should I perform concrete moisture testing and what will I do when I get the results? Finally, what do the concrete moisture control and performance adhesive manufacturer warranties/guarantees REALLY cover?”

Potential Moisture-Control System Customer: “But the specified adhesive states installation can proceed for slabs up to 95% RH?” 

Concrete moisture testing is a snapshot in time in terms of representing slab conditions. This is especially true for older slabs with no sub-slab vapor retarder. In those conditions, slab moisture levels can fluctuate dramatically as conditions change season-to-season, and over time. Heavy rainfall one season and adjacent construction projects that change site drainage patterns can result in increased slab moisture levels which translate to resilient flooring failures when performance adhesives cannot withstand these increases.  Performance adhesive failures can, and do, occur when ASTM-F1869 and/or ASTM-F2170 tested concrete moisture levels are within manufacturer’s stated tolerances, but change at a later date. Finally, to truly protect any project, carefully consider a company that offers a letter of affirmation and/or performance standard characterizations that are inconsistent with the product Technical Data Sheet (TDS) and industry standards.

Potential Moisture-Control System Customer: “Will the performance adhesive manufacturer cover such a flooring failure?”  

In a review of projects and discussions with manufacturer representatives, that answer is generally “NO.”  Adhesive manufacturers are most commonly providing product defect guarantees, NOT warranties that their products will mitigate moisture vapor emissions, even when installation conforms to published moisture tolerances. If an adhesive states a limit of 95% Relative Humidity (RH), whether the resilient flooring is installed with moisture levels below, at, or above 95% RH, the installation is a gamble. More on this topic can be found here. Bottom line:  a product guarantee is a far cry from the “Peace of Mind” that comes from an OBEX 15-Year Warranty which assures flooring replacement in the very unlikely event of a failure.

OBEX’s Position:

OBEX’s experience confirms that performance adhesives are useful as a part of an effective “belt-and-suspenders” approach when paired with a cost-effective moisture control system like Creteseal® CS2000™ for new slabs.  For below-grade or on-grade slabs, a sub-slab vapor retarder should be employed in accordance with industry standards.  More on this topic can be found here. Likewise, when it comes to an existing slab renovation – with slabs installed before sub-slab vapor retarders became industry standard – these scenarios present a high-risk of resilient flooring failure if renovation plans do not include an ASTM-F3010 vapor barrier installation such as the Creteseal® MAX System™.  

For “Peace of Mind” that the flooring system will not fail due to negative-side moisture vapor emissions, OBEX offers concrete moisture control product solutions backed by industry-leading warranties at highly-competitive price points.  Give us a call at 844-265-3535 and ask to talk to a member of our Technical Services Team, or find us at to learn more.  

Good Price, Better Service.


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