Did you know that even after concrete a floor hardens, moisture continues to pass through it for several years? Although concrete slabs have a hard and solid appearance, they are still moist? When making a concrete floor or slab, the builders begin by mixing specific ratios of cement, water, sand, and aggregate. Therefore, initially, before hardening, concrete floors are liquid slurries. Concrete structures, especially residential concrete floors, absorb and transfer ground moisture to the outer surface. When this happens in outdoor concrete applications like walkways and patios, it does not have a significant impact. However, when it comes to indoor concrete application, absorption, and transfer of ground moisture significantly affect the installation of residential concrete floors on the concrete.

concrete moisture

Sometimes a concrete floor might look dry, but it is not completely dry in a real sense. This misinterpretation can be a problem, especially when installing flooring on such concrete. Here is how it works. Since concrete is permeable to water, it gradually sucks up groundwater in vapor form. If the vapor finds any barrier on the outer surface of the concrete, it builds up around it, leading to a significant effect on it.

However, if you give the concrete adequate conditions (time, warmth, space, and ventilation) to dry up with nothing resting on its surface, all the absorbed moisture from the ground will evaporate into the air. The problem comes when you lay flooring directly on the concrete surface without allowing it to dry up completely. In that case, the installed flooring will act as an airtight and watertight barrier. The result will be the accumulation of moisture which has no means of evaporating.

The accumulation of the trapped moisture is capable of creating unnecessary havoc to your indoor concrete floor, including;

  • Creation of favorable conditions for the growth of mildew and mold.
  • Degradation and decomposition of organic flooring matter, including engineered wood, solid hardwood, bamboo, or cork.
  • Bowing, bubbling, and warping of different types of flooring installations.

How to test for the levels of concrete moisture using three main techniques

Concrte moisture

Testing of your concrete’s moisture content is vital before any flooring works on its surface. To effectively and efficiently determine the quantity of moisture your concrete slab releases, you need a relative humidity meter or a calcium chloride kit. Using either of the two pieces of equipment efficiently determines the precise amount of moisture that the concrete still holds. This way, you will be better positioned to install the most appropriate flooring installation and at the correct time. According to flooring manufacturers, their products belong to different categories based on their moisture tolerance levels. With the extra step of testing the concrete slab, you are likely to know the type or class of flooring material ideal for your concrete slab.

If you are an enthusiast of DIY, you still have the option of performing a DIY test on your concrete floor before deciding to invest in any of the above techniques. The DIY test involves observing the moisture on the slab’s surface or in the air. The downside of this method is that you will not get the precise amount of moisture in the concrete floor. Better still, it serves the intended purpose of revealing what you should do next.

Flooring materials and concrete moisture level

Usually, the issue of concrete moisture is more often and persistent in basement locations which are also below-grade locations. The reason is that in these locations, the ground and the room’s air naturally have high humidity. However, the issue of concrete moisture is also persistent in on-grade slabs, particularly the new ones.

Concrete floor contractors mitigate this problem by slightly raising the surface flooring off the slab. At Alamo Concrete Work, we are professional and experienced concrete floor contractors, and our technicians start by installing a layer of sleeper, which is a grid and frame. This grid and framing aim to facilitate an intermediate layer that prevents the flooring material from resting directly on the residential concrete floors. Professional concrete floor contractors place the sleeper system on top of an appropriate vapor barrier to correctly install the sleeper system. Subfloor panels like DRICORE are also suitable for covering the concrete.

To gain a competitive advantage, flooring manufacturers nowadays advertise several of their flooring materials as resistant to moisture. If you want to get genuine bamboos, engineered woods, or cork flooring materials, contact Alamo Concrete Work.


Alamo Concrete Work incorporates professional concrete floor contractors that, apart from identifying our flooring materials as resistant to moisture, we go ahead to ensure their successful application on concrete slabs. At Alamo Concrete Work, all the flooring materials contain specific information about what you need to do during installation to comply and qualify for their warranty coverage. To get the best flooring for concrete slab, contact Alamo Concrete Work at (210) 934-5565. For more information or inquiries.