Preventing Floor Cracking from High Moisture Content

Posted by Tom Laurenzi on Aug 4, 2017 10:30:00 AM

Floor cracking can be a nightmare for any contractor—whether it happens partway through a job, within a few days or weeks after its end. If your newly-installed floors start to split and crack, it surely always results in unhappy customers, callbacks, and unreimbursed expenses.  The best way to deal with this problem is to prevent it from happening in the first place.

What causes floor cracking? The most common cause of cracks is that there was too much moisture in the floor. This can have different effects on different types of flooring:

  • Concrete. Too much moisture in concrete can cause ruptures as moisture in  the concrete  migrates into the wood flooring. It can take a considerable amount of time after a job is finished for these cracks to appear.
  • Wood. In wood flooring, excess moisture in the planks can cause them to swell. If the flooring is installed in this swollen state, splits may occur when the wood dries out.
  • Wood Subfloor. When subfloors have too much moisture, they can swell and lose their shape. This can cause any flooring installed over the subfloor to become uneven or separate from the subfloor.

To prevent floor cracking, it’s vital for contractors to make absolutely sure their flooring doesn’t have excess moisture.

Checking Flooring Moisture to Prevent Cracking

The first step in preventing excess moisture in flooring is to track the amount of moisture it has.  The best way to do this is with a high-quality  flooring moisture meter.

With these tools, you can get a precise moisture content percentage (%MC) measurement in wood, tile, and many other kinds of flooring. This makes it easy to find out if there’s too much or too little moisture in the flooring and reliably predict how the flooring will “behave” after being installed.

Checking Wood Flooring

For example, hygroscopic materials that absorb or let out moisture, like wood, should be checked to make sure they’re in equilibrium with the installation environment. If they aren’t, they could swell or shrink as they take on or lose moisture after installation, causing the wood to warp, crack, or buckle as its %MC changes.

By checking the %MC of wood flooring prior to installation over the course of a few days, you can verify if it is in equilibrium with the environment in which it will be installed. This tells you how likely it is to split or crack after the installation is complete.

Installing Tile Floors

With tile, these checks are a bit different, since many of the most commonly-used flooring tiles in residential and commercial structures are impervious to moisture intrusion. Instead, these checks are applied to the subfloor prior to installation, to ensure it is at the proper moisture level according to the adhesive or flooring manufacturer’s specifications.  

Checking Concrete Flooring

Testing the moisture content in concrete flooring is a very different process than checking moisture in wood or tile. With concrete, a moisture meter can provide a qualitative reading of moisture content since the chemical formulation of concrete can be different from one batch to the next—meaning there’s no universal concrete moisture scale that you can rely on.

Instead, it’s recommended to check the relative humidity (RH) conditions deep in the concrete slab using the ASTM F 2170 standard. This testing requires the use of an RH meter (thermo-hygrometer) and a set of in-situ probes.

This process gives you insight into the moisture conditions deep in the slab so you can tell if it is ready for flooring or coating application.  This also allows you a chance to identify an issue so you can fix it.

For example, if the concrete is taking much longer to cure than originally estimated, it may mean there’s some source of moisture intrusion present that you need to find and fix before moving ahead with your flooring installation. Using a thermo-hygrometer that conforms to the ASTM F-2170 Standard  is required  for this task by helping you find pockets of moisture and tracing them back to their source.

The advantage to checking the moisture in your flooring before, during, and after installation is that it lets you know what your risk of developing cracks in the floor is, and gives you a chance to remediate any problems before they occur.

Of course, to quickly and accurately monitor moisture in your floors, you need the right tools for the job, such as one of Delmhorst’s line of flooring moisture meters. Or, learn more about using moisture meters for flooring by reading our Flooring Guide:

Measuring Moisture in Flooring Systems

Topics: Wood Flooring