High humidity is bad for wood floors

Here in Eastern Nebraska, we’re accustomed to extremes in the weather. We can be frolicking in shorts one day and bundled up in a snowsuit the next—and there’s more than 100 degrees’ difference between the hottest summers and coldest winters. Along with temperature changes each season come changes in humidity levels. Both high and low humidity can damage wood, so maintaining a consistent, ideal humidity level for hardwood floors in your home—regardless of the season—is important for protecting your investment.

As we transition from the humidity of summer to the dryness of winter, it’s a good time to talk about how to prevent your hardwood floors from becoming a casualty of humidity extremes.

What is Humidity?

Humidity is the amount of water vapor that’s in the air. Relative humidity is how much moisture is in the air, expressed as a percentage of the total amount of water the air can hold while maintaining the same temperature. As the air temperature increases, the amount of moisture needed to saturate the air (100 percent relative humidity) also increases. So although Omaha’s average relative humidity in December is 73.8 percent at temperatures in the 20s or 30s, it’s less humid in December than it is in July, when average relative humidity is 68.3 percent but the air is warmer—and holds more moisture.

How Humidity Affects Your Wood Floors

Wood is hygroscopic, which means that when it’s exposed to air, it absorbs or loses water until the moisture content in the wood is in equilibrium with the moisture content in the surrounding air.

If the air in your house has a high relative humidity, the wood in your home will absorb excess moisture. As a result, hardwood floors can swell, which creates pressure between the planks. This pressure can cause the floor to warp, buckle, crown, or cup. Crowning occurs when the middle of the plank rises higher than the edges. Cupping occurs when the edges of the plank rise higher than the center of the plank. In extreme cases, the floor can buckle, or expand beyond the expansion gaps and pull away from the subfloor.

Buckling hardwood floor

Buckling floor due to high humidity


Cupping hardwood floor

Cupping due to high humidity

By contrast, if the air in your house has a low relative humidity, your wood floors will lose moisture. Excessively dry wood floors will shrink, and gaps will appear between the boards. Dry floor boards may splinter or split along the grain.

dry wood floor low humidity

Splintering wood floor, expanding gaps due to low humidity

In the long run, the repeated changing of humidity levels can cause serious problems with your floors. Keeping your home’s humidity stable year-round is the best way to prevent humidity-related damage to your hardwood floors.

Humidity levels affect more than just your floors—it can cause health problems, too. High humidity in your home promotes the growth of mold and bacteria, which can make you sick. Dust mites love high humidity, and if you’re allergic to these microscopic beasts, your allergies will flourish. High humidity can also worsen asthma and other respiratory conditions.

Low humidity creates an environment where viruses and bacteria thrive. Viruses tend to linger in dry air longer than they do in air that’s more moist. Low humidity can cause or worsen respiratory infections, and it, too, can worsen allergies and asthma.

What is the Best Humidity Level for Hardwood Floors?

The recommended humidity level for hardwood floors—and your health—is between 38 percent and 42 percent. You can test your home’s humidity level with a humidistat or a hydrometer, both of which are available at your local hardware store. Maintaining stable humidity year-round is important for maintaining good health and keeping your wood floors in tip-top shape.

Signs Your Home Humidity Level is Too Low or Too High

Watch for these tell-tale signs that your humidity level is too low. This will usually happen in the winter:

  • Dry, itchy skin
  • Increased static electricity
  • More colds/flu/respiratory illnesses than usual
  • An increase in bloody noses
  • Increasing size of gaps between floor boards
  • Houseplants turning brown or not growing

If your humidity is too high, you may notice these signs:

  • Air that feels clammy and moist
  • Foggy windows
  • Musty smell
  • Signs of mold on the walls or ceiling
  • Worsened allergies

How to Keep Your Home Humidity Levels Stable All Year Long

The best way to maintain stable humidity in your home is to check the relative humidity often, and act promptly when humidity goes above 42 percent or below 38 percent.

In the summer, when humidity is high, keep your air conditioner on to condense the excess humidity in the air, which then leaves your home through the HVAC condensate drain. Ventilation helps keep humidity down, as well. When it’s not hot enough for the A/C, turn the fan position to ON to keep the air moving. Turn on your bathroom and kitchen vents when you’re cooking or bathing. During the heat of the day, keep the curtains closed so that the sun doesn’t heat up your rooms and trap moist air inside your house—a classic greenhouse effect.

If you’re having trouble keeping humidity down in your home, consider a whole-house dehumidifier, which is installed directly in your HVAC system and pulls moisture from the air that moves through. Unlike a portable dehumidifier—which is also a solution, although a cumbersome one—a whole-house model is quiet, out of sight, requires little maintenance, and best of all, it doesn’t need to be emptied daily.

In the winter, combat low humidity with a whole-house humidifier. Like its dehumidifier cousin, a whole-house humidifier is installed in the HVAC unit and moistens the air in the entire house. Don’t use a portable humidifier in rooms with hardwood floors. These models can make the immediate surrounding air too moist, causing droplets to fall from the air and damage the floor around the unit.

Address Humidity-Related Damage to Your Hardwood Floors

If your floors have damage related to high or low humidity, Lifetime Hardwood Floors can help. We have the equipment and expertise to fix your floors—or replace them if necessary. Call us today for a free consultation, and we’ll restore beauty to your floors and help you address the cause of the damage so that your floors will last a lifetime.


Covid-19 Message: Your health and safety is our first priority. Our residential projects involve a one-person crew, and we take all necessary precautions to protect you and your family while your floors are being restored.