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HomeArchiveCase Study: Adhering Flooring to Concrete Substrates

Case Study: Adhering Flooring to Concrete Substrates

A Case Study in Due Diligence

By Dave Doherty and Phil Romah, Tego Systems


Concrete 2
Spreading of concrete.

When it comes to adhering flooring materials to concrete substrates, there are numerous hurdles to overcome, and much important research to be completed for a successful installation. Let’s put aside the environmental (HVAC/Humidity) issues and focus on the concrete itself. This includes concrete that is below-, above- or on-grade. This is not all inclusive.


Concrete 3
Working on a concrete floor .

New Concrete

  • Is there a proper moisture barrier beneath the slab?
  • Was the concrete placed correctly?
  • Was the concrete allowed to cure properly?
  • Is there an admixture in the concrete itself to assist in curing that may be deleterious to the adhesive bond?
  • Is it Lightweight Concrete? This is important regarding In-Situ testing.
  • Is it hard troweled and therefore mainly non-porous?
  • Is there a chemical moisture barrier adhered to the surface (new and existing)?


Concrete 4
Concrete slab prepared for residential house construction.

Existing Concrete

  • Were there previous moisture problems or flooring failures?
  • What was the previous flooring material?
  • What type of adhesive residue is on the surface of the concrete?
  • Was the previous adhesive removed mechanically or chemically?
  • What was the space previously used for? Consider a machine shop that contaminated the slab for decades with oil and other contaminants. These types of mill-type buildings are being converted all over the country.


Concrete 5
A new concrete slab.

Q: The old flooring has been down for many years and didn’t fail. Do I still need to test for moisture?

A: Yes. Just because the older material(s) didn’t fail does not factor into the moisture testing requirements for the new material or patching compounds:

  • Many older flooring materials contained asbestos which is resistant to moisture and would not be a comparison to today’s materials/backings.
  • Older adhesives were solvent-based, which were not as susceptible to moisture related degradation.
  • There could be a major construction site nearby, or other environmental factors that may have inadvertently changed the water table beneath the slab.


Concrete 6
Construction workers viewed from above,

The Flooring Contractor must test for the two major causes of adhesive failure – Moisture and Alkalinity, while following proper ASTM and Manufacturer standards. Concrete is naturally alkaline and moisture vapor brings this to the surface. This killer combination is a major factor in flooring failures around the world.

Bottom line – do your homework and test, test, test. Look at the installation with a wider scope. Be sure to carefully document the test results. This is an inexpensive insurance policy.

iStock photos courtesy of Tego Systems


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