6 ways humidity can affect your hardwood flooring

Posted on Mar 26, 2019


Photos by: Lauzon Flooring


Feet on Hardwood Flooring


Summer is right around the corner and there are some things that home owners need to be aware of. Humidity levels are the number one thing to take into consideration when the seasons change. Wood after all is a natural material that still needs to breath in order to stay healthy.


When winter comes you will have you turn up the heat and take the same thing into consideration. Did you ever think about how these living conditions and changing humidity levels inside your home can affect your beautiful new hardwood floor?


Your hardwood floor is made of… wood! And wood is a natural material that reacts to changes in its environment even after it has been transformed into flooring. Yes, manufacturers have developed different types of hardwood floor constructions to “improve and control” the wood natural reaction to changes in humidity. But keeping humidity at the recommended level is still essential for keeping your hardwood floor looking great, as well as for a healthy home environment.






Proper humidity level for your health


The (EPA) United   States  Environmental  Protection  Agency   lists indoor air quality among its top environmental health threats. Another good thing to consider is the quality of the manufacturer and the source of the flooring. Consumers need to make sure the manufacturer is sourcing quality north American lumber and using acceptable staining and preserving chemicals to make sure they have below standard off gazing levels.


There are three key components to healthy air: it must be fresh, clean, and have the proper humidity level.


The ideal relative humidity for your health and comfort is about 40-50%.


 During winter : It may need to be between 30-40% to prevent condensation on your windows and other surfaces. Relative humidity settings that are too low may cause respiratory infections, allergic rhinitis and asthma.


–  During summer : It can move up to 50-55%. Relative humidity that is too high may have health effects due to mold growth, dust mite infestations, as well as certain bacteria and viruses.

To discover how Lauzon is going the extra mile for your health, by purifying indoor air with our Pure Genius hardwood floors,  click here .




Proper humidity level for your hardwood floor


The  National Wood Floor Association  (NWFA) states that normal relative humidity levels should range between 30%-50% to ensure successful long-term performance of your wood flooring.

As we just saw, however, this range can often be difficult to achieve in certain areas of the country during certain seasons. This is why at Lauzon, we have developed three different types of hardwood flooring constructions allowing you to enjoy the beauty of hardwood floors no matter where you live.  


– Relative humidity levels of  30-80%  –  Expert  engineered  Lauzon hardwood floors
– Relative humidity levels of  35-65%  – Other Lauzon  engineered  hardwood floors
– Relative humidity levels of  35-55%  – Lauzon  solid  hardwood floors.


As you can see, engineered wood flooring is more stable than solid wood flooring. One of the reasons for this is that the bottom layers are made of cross-sided layers that move on opposite sides. If you are looking for maximum performance during humidity changes, take a look at our  Expert  ¾ construction, which was developed to meet contractors’ needs.

types of floors



Your hardwood floor during the dry season

During the winter, when homes are heated and the air is dry, wood flooring loses some of its moisture and contracts or shrinks as a result.


Hardwood flooring dryness problems:


It is normal that when relative humidity is lower than recommended,  wood plank shrinks, therefore thin gaps can appear between wood planks. Even if the right term to use is gaps, these small gaps between the wood planks can sometimes be called cracks or spaces between wood planks by consumers. Having gaps between your wood planks is normal, and a homeowner should be prepared for it to occur. Once humidity levels rise again, the hardwood floor will expand and most gaps will close up again.


 Splits & Checks
When the wood is faced with extreme conditions, it can be stressed beyond its limitations. Therefore the wood weakens, making your hardwood floor more brittle and increasing the likelihood of damage or splintering. The boards themselves may split, check or crack in the centre or at the ends, or both, along the grain, damaging the finish. This damage is permanent, because your hardwood floor finish is cracked—your wood is no longer protected.


gapping and splits


Preventing dryness problems


– Maintain a proper humidity level in your home by using a humidifier during the winter months.
–  Be aware that wood stoves and electric heat tend to create very dry conditions, so make sure to use your humidifier when these are on.
– If you are a “snowbird” and leave your home unoccupied for weeks at a time, make sure to always keep temperature and relative humidity at recommended level.






Your hardwood floor during the Humid Season


During warm and humid summers, your hardwood floor will absorb moisture from the air, swelling and expanding as a result. This expansion can create pressure between the boards, which can cause the boards to warp, cup or crack. Both cupping and crowning are natural reactions to   moisture and should not be of concern if they occur only to a minor extent. More severe cases, however, indicate a serious moisture problem.


Hardwood floor moisture problems:



When a wood plank cups, its edges become higher than its centre. This is a reaction due to a humidity level disproportion in the wood plank. There can be numerous causes to cupping, including an excessive level of relative humidity, relative humidity migrating from a basement or crawl space, water infiltration, etc.


Should cupping occur, it’s important to quickly identify the root cause in order to rectify the situation. It will then take some time for the wood flooring to get back to its normal internal humidity balance and shape. In some instances, the use of fans and/or dehumidifiers might be necessary to bring everything back to normal.


 Crowning :
Crowning is the opposite of cupping. The middle of the board is higher than the board’s edges. This can occur when the surface of the floor encounters moisture. It most often occurs when a floor has been sanded too soon after cupping. When this happens, the top edges of the board are sanded off and are therefore lower than the rest of the board when returning to a normal moisture content.




Buckling is one of the most extreme reactions to moisture that can occur with hardwood flooring. It happens when the floor expands beyond expansion gaps and literally pulls away from the subfloor, as high as several inches. It’s like walking on a trampoline. Once the humidity drops, the floor may shrink back, but it is possible that you may see spaces between the wood boards.


–  Cracking :
When extensive moisture or humidity causes the wood to expand significantly, adjoining boards start pressing against each other. In extreme cases, this increased pressure can cause the affected boards to lose their structural integrity and crack.


Preventing moisture problems:

– Make sure you leave free expansion space around the perimeter of your floor when installed. For aesthetic purposes, they are usually covered with baseboards.
– Maintain proper humidity levels with an air conditioner, dehumidifier or by turning on your heating system periodically during the summer months.
–  If you go away on a long summer vacation, leave the A/C on.
– Avoid excessive exposure to water from tracking during periods of inclement weather.
– Clean your hardwood floor with a cloth lightly dampened with a recommended hardwood floor cleaning product.
– Choose a good quality engineered hardwood floor that will fit with your needs.

installing hardwood


I t is important to be aware that none of the damage caused by humidity variations is covered by any hardwood floor warranty. It is your responsibility to make sure you have a stable environment in your home, even when the home is unoccupied.


That is why all homeowners should own a hygrometer to measure the temperature and relative humidity (RH), and be sure to respect the guidelines above.

Always keep in mind that keeping the humidity and temperature level at the recommended level is not only essential for keeping your hardwood floor looking great, but also to provide you with a healthy home environment!


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