Moisture And Your Hardwood Floor

October 22, 2018 - 11:03am

Wood floors are one of the rare building products that inherently showcase the natural beauty of the material itself, which is why wood has been used as a flooring material for centuries. One of the keys to ensuring a wood floor’s timeless beauty is having a fundamental understanding of the relationship between moisture and wood.

Hardwood flooring is a natural product that will respond to different humidity variations. This means that even though the wood has been dried, cut, and processed into flooring material, the hardwood may expand or contract because of moisture. A change in seasons is when these changes become especially noticeable. During warm and humid summers, hardwood flooring expands. During dry winter weather, hardwood flooring contracts. Because this seasonal movement is normal for hardwood products, the best way to reduce such movement is by installing humidity controls.

Wood is a hygroscopic material.  When wood is exposed to air, it will either dry or pick up moisture until its reactions occur at equal rates with the humidity and temperature of the air. When the moisture is absorbed, the wood will swell. Wood will begin swelling as the moisture levels increase anywhere from 55%. When the moisture is lost, the wood will shrink. Shrinkage of wood begins at 25%. That means that gaps may start showing.  Nearly every solid wood floor presents some separation between the individual boards – gaps– throughout the floor. In the winter months, when the air in the building is heated, the surrounding air loses moisture and relative humidity levels drop.

When this happens, moisture is lost and gaps appear between individual boards throughout the floor. This a normal phenomenon and is directly related to the
environmental conditions the wood is being exposed to. Once the interior heating systems are turned off and the indoor environment regains moisture, most
of these seasonal gaps will disappear. The only way to avoid seasonal change in wood flooring is to maintain consistent relative humidity levels throughout the year.
It is important not to fill seasonal gaps when they appear as this could cause subsequent damage to the wood flooring as it expands again in the humid seasons.
Seasonal gaps between boards are more prominent with solid wood flooring products than with engineered wood flooring products. The structural composition of engineered wood flooring allows it to be more dimensionally stable than solid wood flooring. Abnormal gaps are those that remain with seasonal change and should not be confused with normal, or
seasonal gaps.

Anything between 30 - 50% means that your hardwood flooring is dimensionally stable. Hardwood does not shrink or swell equally in all directions. A change in moisture content of a piece of hardwood flooring will increase the size of the piece approximately 0.1% along the LENGTH of the board, and 5% to 15% change in size in WIDTH.

Love a nice fire and cozying up in blankets during winter time?

Your hardwood flooring doesn’t. Because your home is normally heated during cooler months, your hardwood flooring gives up some of its moisture and contracts. Naturally, when this happens, thin gaps can appear between planks. As a homeowner, you should be prepared for this to occur. However, to try to prevent these separations, you can install a humidifier in the furnace or bring a movable humidifier into the room. If your humidity doesn’t fall lower than 30%, no gaps should appear between your hardwood flooring planks. Generally, once the weather starts to warm up for springtime, heating is turned down and humidity levels will naturally rise. In turn, most of the gaps in your hardwood flooring material will close on their own.

You may be thinking that it’s going to be impossible to avoid these seasonal issues, but that’s not the case. Just follow these steps:

  • Be aware of things that change humidity.
  • Purchase a hygrometer to keep an eye on the humidity.
  • Maintain a consistent relative humidity level of 30-50% throughout the year.
  • Use a humidifier in when the humidity is low and a dehumidifier if humidity is high.

If you have changes in your hardwood floor that do not return to normal after seasonal changes, contact us for information or possible repair.