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Hardwood flooring is a great choice that can last a lifetime. But did you know that you could easily lose this lifetime investment if you don’t fully acclimate the hardwood before it’s installed?

Extreme moisture-related issues may occur, such as warping, cupping, crowning, buckling, mold, mildew, or even noticeable gaps between boards. Oftentimes, problems like these entail costly repairs.

Just like any type of wood, hardwood is sensitive to the moisture around it. That’s because wood is hygroscopic, meaning it will absorb or release moisture depending on ambient temperature and relative humidity (RH).

Big issues if you don’t acclimate the wood

Generally, if you fail to acclimate the hardwood flooring and install it when the moisture content (MC) of the wood is too high, it may compromise the integrity of the flooring. You could run into big issues that you won’t even know about until later.

Let’s take a closer look at some of the serious issues that could arise.


Warping is any deviation from being flat and can be a common issue when wood flooring absorbs moisture unevenly or dries too slowly or too quickly. Warping can take several forms and can give the flooring an undesirable twisted, bowed, or crooked appearance. If the boards do not revert to their original shape, they could separate, splinter, or crack.


Wood floor cupping is a type of warping that occurs when the edges at the side of each plank stick up higher than the centers. The floor ends up looking a bit like an accordion or a washboard. Any moisture imbalance, including a change in the surrounding environment, can cause the boards to expand further than the space given them during installation. The resulting pressure forces the board edges upward, which creates the washboard effect.


When a wood floor buckles, it’s really an extreme case of crowning, in which the center of each board is higher than the edges. But with buckling, dramatic moisture changes will curve the boards to the extent that they lose contact with the subfloor. This happens most often in response to prolonged exposure to excessive moisture, such as after a floor has been flooded for a while. However, incorrect installation can also be a contributing factor.

Abnormal gaps between boards

Narrow spaces between boards are common and are due to seasonal variation as ambient RH changes. Realize, though, that if the flooring was installed when the MC was significantly higher than the ambient conditions, the spaces between boards can grow unacceptably large as the boards dry. The wider the board, the wider the gap will become. Large gaps can also be related to environmental issues, such as a “hot spot” created by an appliance.

The solution is simple

In nearly every case, it’s surprisingly easy to avoid these moisture-related issues. Since they’re all due to moisture, your best line of defense is to pay attention to the MC of the hardwood before installation.

Don’t just assume that the hardwood will acclimate properly within a few days or so after it’s delivered to the job site. Instead, protect your investment by also investing in a high-quality, nondamaging pinless wood moisture meter that can take MC readings down to 5-6%.

When your hardwood flooring arrives on-site, use your moisture meter right away to take MC readings and get baseline information. Then continue to monitor the MC until the wood reaches equilibrium moisture content (EMC). This is a calculated number based on ambient temperature and RH. It represents the MC at which the wood is no longer absorbing or releasing moisture.

Some meters, such as the Orion 950 by Wagner Meters, have a built-in thermo-hygrometer that measures ambient conditions and then calculates EMC for you. Typically, you’re looking for an MC in the 6-9% range, but this will vary by geographic region and other environmental factors.

The bottom line

Remember: because wood is sensitive to moisture, you always want to measure the flooring’s MC before you install it.

For more information about moisture in wood flooring or how to choose the the best wood moisture meter for your situation, visit our rankings of topWood Moisture Meters reviews page.