How Humidity Wreaks Havoc on Your Hardwood Floors

floor cupping due to water damage

Wood is a hygroscopic material, meaning that it absorbs moisture from the air around it. The amount of moisture in wood (known as “moisture content” or MC) is often expressed in terms of percentages. Green wood (meaning freshly cut) may have an MC ranging anywhere from 30% to 250%. The MC of a freshly cut piece of wood varies depending on the species of wood, time of year, and other factors.

After being cut and dried in a kiln, the MC usually drops down to somewhere between 6% and 8%. However, the moisture content of dried lumber may vary greatly depending on the humidity in the space where it’s stored, the species of wood, and the cut.

Wood swells when it absorbs moisture, and it shrinks when it dries. Meaning, anything made of wood–whether that’s a piece of furniture, a doorway or hardwood flooring–may swell and shrink over time. Any conscientious owner of hardwood should be aware of the effects of MC on wood, and how to deal with complications appropriately.

Hardwood Floors and Humid Environments

Hardwood floors in humid environments will swell. Depending on the amount of swelling that takes place, the quality of installation, and the amount of space between boards, hardwood floors may become warped. Often, the bending and warping of these boards is referred to as “cupping,” because the edges of the boards become raised. In very wet conditions, humidity may even cause floors to rot.

Hardwood Floors and Dry Environments

Excessively dry air is no better for wood, because moisture helps wood retain some suppleness, which helps it adapt to different environments. In winter months when the air is dry, hardwood floors may have gaps between the boards, due to shrinkage. Hardwood floors in dry air may also become brittle and fragile, develop squeaks and even crack.


Anyone who chooses to install hardwood floors in their home must understand that hardwood is beautiful, natural, and imperfect. Environmental conditions are changeable, so to some degree, shrinkage and swelling is expected. However, preventative measures taken before and at the time of installation can make all the difference.

Proper installation of hardwood floors. Hardwood floors should be acclimated to your home before installation so the boards can reach a balance with the air in your home. This will prevent shrinkage or swelling at the time of installation.

Smart consumer decision-making. Hiring the right installation company to install your floors will ensure that all preventative measures will be taken to avoid issues related to swelling and shrinkage. Contract Carpet One is dedicated to using the best team for the job, and offers one of the best post-installation warranties available.

Maintain appropriate environmental conditions. Some homeowners choose to purchase dehumidifiers and humidifiers for wet and dry times of the year. Some even install centralized environmental control systems (such as a centralized de-humidifier) to control the conditions in their home. This is one way to handle the problem, but if the hardwood floors have been properly installed, cupping and excessive shrinkage should not be a problem that requires the installation of a special household wide environmental control system.

Pick your hardwood flooring carefully. Some types of wood and cuts are more stable and less prone to moisture absorption. Homeowners who are concerned about potential cupping in summer months or excessive dryness in winter months must pick their hardwood flooring carefully.

Residents near the Washington, D.C.–Beltsville, Maryland area seeking more advice on purchasing the best hardwood floors for a humid environment should speak to a professional at Contract Carpet One. We offer free hardwood design consultations, and are happy to help you choose the right flooring for your home.

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