Moisture Testing Can Save Thousands in Ruined Floors: What to Look for and How the Test Works


A customer in Boxboro recently became frustrated as they noticed the tile in a sensitive lab area becoming discolored and curled. This problem was unsightly and created a potential trip hazard across the entire floor. They asked themselves:

How did this happen? Was the original installation poor? Was the adhesive insufficient? In any case, they decided the solution was to replace the floor. We were called in and asked to provide a price for removing the existing VCT and installing new tile properly. At our suggestion, the company quickly agreed that a moisture test was in order.

We were surprised to hear that no other commercial flooring company had suggested this simple test, which determined the root cause of this failed floor to be water pressure – 13 pounds per 1,000 square feet in 24 hours, as well as a high pH.

What was the problem?
Over time, moisture and alkaline under resilient flooring cause adhesive deterioration, which leads to bumps and ridges, color change, and also encourages mold, mildew and bacteria growth. Even new concrete slabs, built to manufacturer’s specifications can experience unacceptable levels of hydrostatic pressure for today’s resilient materials. The generally accepted maximum threshold for moisture and pH is less than 3.0 pounds per 1,000 square feet in 24 hours, with a pH of 7 to 9. Because hydrostatic pressure and a naturally high pH are properties of hardened concrete, we recommend performing the flooring industry-accepted calcium chloride test for all concrete slabs.

In the end, the information gleaned from this approximately $500 test, enabled our customer to insure that the investment they made in their new floor is now secured.

The floor has now been treated with a moisture barrier that is rated for up to 24 lbs. per 1000 SF. It has reduced the moisture content in the slab from over 13lbs. to almost nothing. The floor was prepared properly and is now certified/warranteed by the manufacturer of the moisture barrier for the life of the floor. We have supplied and installed new tiles, and the customer now has a new floor in their lab which should last for years to come.

How does the test work?
The calcium chloride vapor emission test was developed over 40 years ago to quantify the volume of water vapor radiating from a concrete slab surface over time. It is recommended that every 1,000 square feet should be tested individually, and should be conducted in a representative interior climate. By using a sensitive gram-weight scale prior to and directly after exposing the calcium chloride test unit to the concrete slab, the test can determine the weight of water, emitted as vapor, in a 1,000 square foot area in 24 hours.

The results of this test can then be compared to the manufacturer’s recommendations for the materials to be installed, and if it meets the approved criteria, the materials can be installed under the manufacturer’s warrantee. It’s important to note: flooring manufacturers don’t only limit their liability for products installed on a slab with moisture and pH issues – they recommend you opt not to install them. However, with the right contractor, following the right procedures, you can install whatever flooring matches your taste and budget.

What if the floor has a moisture or pH problem?
If a slab shows water pressure or pH outside the recommended boundaries, moisture barriers and sealing products can reduce these conditions to acceptable levels, and if applied properly, the sealant manufacturer will certify the floor, enabling the installation of resilient flooring under the manufacturer’s warrantee.

The bottom line.
With flooring trends moving from porous materials, like carpet — which allow moisture to pass through — toward more resilient and often more costly materials, such as tile, wood and laminate, knowing the facts about moisture can make the difference between a long-lasting flooring investment, and a buckling, moldy eyesore.

Resilient floors, when properly installed, can outlast less expensive options, but they’re very susceptible to moisture. Simple, inexpensive tests can determine whether the concrete is within industry guidelines, and if not, a reliable flooring contractor can help bring the floor to within manufacturer specifications.