Adhesive Breakdown and Flooring Betrayal

Removing Tile Floor
The new floor is in, and the diplomats are arriving for the show. What’s that smell? Why is glue seeping from the cracks between floor tiles!? Welcome to an adhesive breakdown in flooring, a catastrophic product of moisture content and high pH.

Moisture vapor naturally evaporates from the surfaces of all concrete floors. If installers used a calcium chloride test to measure a moisture vapor emissions rate (MVER), they learn that the floor contains 2.76 pounds of water crystals per thousand square feet of floor. Generally, moisture vapor experts do not install floor covering materials with an MVER rate exceeding three-to-five pounds. In this scenario, the contractor likely proceeded, because the MVER read less than “3.”

If the floor suffered an adhesive breakdown and only surface testing was conducted, the internal relative humidity (RH) would have potentially shown higher levels of moisture. In a high RH environment, moisture vapor can contain high pH levels in concrete. If high enough, high pH causes adhesive breakdown due to high RH. The floor fails because its covering does not adhere to the subfloor. Application fluids leak instead of sticking. If so, the high pH of moisture vapor is the culprit.

MVER Tests

Adhesive for Wood FlooringThe calcium chloride test, known as MVER, was developed in the 1950s. It consists of sealing a dish with a known weight of anhydrous calcium chloride crystals to a concrete surface for 72 hours. Builders then calculate the MVER by calculating how much moisture the crystals absorbed. Floor materials manufacturers generally recommend that installers confirm a “3” or “5” emissions reading before proceeding.

Industrial evolution has revealed cracks in MVER’s methodology. Put simply, MVER does not account for high pH or high RH in moisture vapor levels. Calcium chloride testing cannot help contractors avoid adhesive breakdown because MVER does not indicate RH deep in the concrete.

Relative Humidity Tests

Contractors have a new ally: RH testing. RH measurement detects high RH levels before contractors mistakenly apply floor coverings to subfloors that are outside the limits set by the adhesive or flooring manufacturer. Wagner Meters provides cost-effective moisture content tests based on RH. If high RH causes high pH, moisture metrics will put a stop to floor covering installation before it ruins the project. Hand-held digital meters from Wagner Meters arm contractors and consumers with the means of identifying potential high RH and the need for further testing before it produces adhesive breakdown.

Question: “How could you blow something as simple as moisture content measurement?”
Answer: You wouldn’t blow it with a Wagner moisture meter.

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Last updated on July 20th, 2023


  1. Tile Contractors Portland Oregon says:

    The issue you have talked about here it’s all are important to know for all. Thanks for this content.

  2. Jon Beattie says:

    This is happening in one of my basement rooms (We didn’t install the flooring, but the prior owners did not too long before selling the house). Will a dehumidifier in this room help with this issue? (for reference, the same flooring was installed throughout the rest of the basement and there is no issue like this with the rest of the basement floor).
    Thank you for your help!

  3. Freddie Curry says:

    If the subfloor is not level throughput within manufacturing specs , what possible problems could arise in the future??

    • Jason Spangler says:


      Thanks for the question. The question isn’t level as much as flat. Without flat, flooring may not adhere properly to the subfloor, there can be hollow spots, and/or flooring can break or crack, just to name a few things. This is obviously dependent on the type of flooring product being installed.


  4. john hecko says:

    Can something in concrete react w/flooring adhesive and cause heat?
    About a year ago after plumbing backup that could not be cleared, wood flooring and concrete removed to reveal deteriorated cast iron piping. New plastic pipe, concrete and flooring installed. Now dark areas appearing on wood flooring and they are very warm. Warm enough that I would guess that under the wood it will be HOT. No evidence of moisture but I think the spots generally follow where the repairs were done.
    Would appreciate your expertise and thoughts.
    thanks, John

    • Jason Spangler says:


      I can’t say I have ever heard of flooring adhesive causing heat under the floor. I would contact NWFA, National Wood Flooring Association, and see if they can recommend someone to come take a look at the floor and diagnose the problem. Good luck.


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