Your Floor’s Beauty May Be Hiding a Beast Inside

Previously published by The Flooring Contractor magazine

Uncontrolled Moisture Can Do Dastardly Things to Your Hardwood Floor

hardwood flooring with no moisture problemsYou’ve worked hard, and you’re extremely pleased with the results. You step back to admire the hardwood floor you’ve just installed. You’ve carefully attended to its every detail. Each board has been tightly and strategically fitted with its neighboring board to achieve a truly beautiful effect. You are confident that your customer will happily use this floor for decades. No doubt many important events, celebrations, and conversations will be enjoyed here. You take satisfaction in how your floor will quietly play a vital and significant role in each one.

But what if there is a problem? A big problem. Something that will absolutely wreak havoc and ruin everything you’ve worked so hard to achieve with this floor installation. What if it’s a hidden problem, one you can’t even see or measure in the hardwood floor itself?

Do you know that the #1 problem that can mess with the beauty of a hardwood floor is moisture? And that even if you’ve measured the moisture content of the wood flooring and found that it meets the manufacturer’s specifications for installation, you may not have touched where the truly troublesome moisture may be lurking.

“Inside” Moisture and How to Measure It

That hidden moisture may eventually make its way into the hardwood floor and cause a whole host of catastrophic issues. These can run the gamut from cupping, crowning, buckling, cracking, shrinking, and warping, to mold and mildew. Just one of these issues may mean a flooring failure that can cost at least as much to repair or replace as the original floor.

The real moisture culprit may be residing underneath the hardwood floor in the subflooring. Is it concrete? Then know that a key step in minimizing the risk of a moisture-related flooring failure is to assess the moisture condition of the concrete slab. That’s because water is one of the most important ingredients in concrete. Surprising as it may seem, substantial water has to be present to give concrete its characteristic strength and durability. Just because a concrete floor slab looks perfectly solid and dry on the surface does not mean that water inside the slab won’t do serious damage to your hardwood floor.

Always—yes always—assess the moisture condition of the concrete slab prior to your flooring installation. NEVER rely on surface measurements only, such as the anhydrous calcium chloride test. Much of the moisture is likely to be hidden deep in the concrete but you can’t expect it to just stay there. After your installation, some of that moisture will move to the surface and interact with the finished floor product. For this reason, it is important to assess with accuracy the moisture deep inside the slab. This means making sure the slab’s moisture condition gets evaluated using the scientifically proven in situ relative humidity (RH) test.

The most popular of the available RH test kits is the Rapid RH L6 by Wagner Meters. It is accurate, reliable and simple to use and even allows you to download your data wirelessly to your smart device using a free app. As with all in situ RH tests, you can get your answer on the slab’s moisture condition in as little as 24 hours once the job site has been stabilized at service conditions for 48 hours. Service conditions are the building’s temperature and RH when placed into service.

Always Assess the Wood’s Moisture Content

Wagner Orion 950 pinless moisture meter

The simplest way to monitor the moisture levels in your wood is to use a handheld moisture meter calibrated for the type of wood that you are installing.

Of course, minimizing the potential for moisture problems also means assessing the finished floor product itself. What is the ideal moisture content for wood flooring? The answer depends on the ambient temperature and RH conditions at your job site. Wood is hygroscopic and absorbs and releases moisture until it reaches equilibrium moisture content (EMC) with its surroundings. Therefore, the ideal moisture content for installation will be the EMC. If the wood flooring is at EMC, then it is fully acclimated to the environment, and that’s what you want.

The EMC will vary by temperature and RH. If RH is between 40% to 45% and the temperature inside the building is between 75 to 85 degrees Fahrenheit, then the EMC of your wood should be about 7% or 8%. But if the job site is in a more humid environment, say along the coast, and average RH values are higher, your target EMC may be closer to 11%.

How should you check the moisture content in wood? The simplest way is to use a handheld moisture meter calibrated for the type of wood that you are installing. Not just any moisture meter will do, and lots of choices exist. Make sure the meter you use is highly accurate and can be easily checked for proper calibration. It won’t do you any good if the meter you are using is out of calibration or gives readings that aren’t very close to the actual moisture content of the wood.

Wagner’s Orion line of wood moisture meters makes a great choice. These meters feature built-in settings for lots of different species of wood. And because they can be calibrated in the field, you always have peace of mind that you are getting accurate readings. Use the Orion 950 and you can also readily assess the job site’s ambient conditions with the integrated sensor for temperature and RH. It’s a great way to monitor that the building is at service conditions at the time of your installation.

Free Download – 6 Reasons Your Wood Project Failed

Ensuring Your Floor Performs Well After the Installation

Let’s say you did your due diligence. You made sure prior to installation that the moisture condition of both the subflooring and the finished floor were within the manufacturer’s specifications. Then you completed the installation with beautiful results. Does this mean there is no danger of a flooring failure due to moisture?

Lots of things, of course, can happen after the building is put into service. If care is not taken to keep the building within service conditions, wide swings can occur in the amount of moisture in the air. If you’re in an area with humid summers and dry winters, for example, your wood floor can react to the changing humidity in the air. The wood can expand during one season and contract in another. These types of changes could spell trouble. Leaks, spills, or improper care or cleaning of the wood flooring can also lead to significant moisture-related problems.

Wouldn’t it be great if you had a way of monitoring ambient conditions at the job site after your work is done? If a flooring problem were to occur later, you would have important information about whether the proper conditions for the long-term performance of the floor were maintained.

Smart Logger with smart app

The Smart Logger from Wagner Meters is a discrete temperature and relative humidity data logger that records up to 12,000 readings of ambient conditions data for up to 300 days of replaceable battery life.

The solution? Install a small, portable device called the Wagner Smart Logger that measures and stores ambient temperature and RH even when you’re not there. It’s an additional way to show your customers that you are state-of-the-art, plus it’s an opportunity to explain to them the importance of maintaining service conditions. And it gives you another touchpoint with your customer when you return later to retrieve your data logger.

For more information about wood or concrete moisture and how best to measure it, contact Wagner Meters at (800) 207-2530. You can also check out the valuable resources and training offered at the International Concrete Repair Institute (ICRI) at

Last updated on May 4th, 2021

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