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  3. Resources and Other Common Concrete Moisture Questions

I just tore up a floor that had no issues and was adhered to the concrete fine. Now I am getting ready to install a new floor and the concrete is testing high RH%. How is this possible?

Again, there are a number of factors that might be at play here:

  • Moisture intrusion that has not yet impacted the flooring
    If moisture has begun to impinge on the slab from a new source, it’s possible that the slab RH has been on the rise but that it has not yet reached critical levels. Moisture seepage through a vapor retarder with an insufficient perm rating, leaking plumbing, new groundwater sources, and other possible moisture intrusions can impact a concrete slab over time and will require remedial steps to correct before installing a new floor over the slab. Testing with the Rapid RH can help spot potential problems before a new floor system is adversely affected.
  • The moisture tolerance of the original adhesive
    With the move to newer, “greener” products in the building industry, moisture tolerances are not always as predictable as they once were. Products heavy in petroleum-based components, for example, are inherently less susceptible to moisture. When re-installing the floor, however, it’s important to either take remedial steps to bring the RH levels down or to be sure that all the new materials specified meet the current RH levels of the slab. The Rapid RH system makes sure that the slab moisture readings inform those decisions for the best results over time.

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