Wood flooring is a natural product that responds to humidity variations by expanding and contracting to different degrees according to varying levels of moisture. These changes may be noticeable at times, like during humid summer’s, wood expands and simultaneously during dry winter’s hardwood contracts. This seasonal movement is always normal for hardwood flooring. Moisture absorption causes hardwood to swell and moisture loss causes wood to shrink. Shrinkage of wood begins at 25-30% moisture content. Swelling occurs as wood increases in moisture content from 0% to 25-30% moisture content. Above 25%-30% wood is dimensionally stable.
The best way to reduce such movement or to prevent it completely by installing humidity controls and making sure that they function before flooring is installed. There are a few things you need to know about hardwood and humidity levels to keep your floor in great shape and strength.
Let us see the affects of humidity in humid summers and dry winters on Hardwood Flooring-
Humid Summers Time-
During warm and humid summers the indoor humidity can rise up to levels of 90%. Wood absorbs moisture from the air and results in expanding your hardwood floors. Even a mild exposure of humidity in summers can cause your hardwood floor to cupping. Cupping can also happen when spilled water is absorbed by hardwood. Once cupping is occurred on hardwood, it takes time for the wood to refurbish its internal moisture to normalcy and flatten out.
When widespread of moisture or humidity causes the hardwood to expand drastically and start adjoining boards against each other. In extreme cases, this increased pressure can cause the affected boards to lose their structural integrity and start cause cracking of hardwood. To avoid cupping, keep indoor humidity level within 40-60% range and never allow indoor humidity levels to rise above 65%. Always maintain optimal humidity levels in your home by keeping dehumidifier or air conditioner running during hot humid summer weather.
Dry Winters Time-
In the chilled winters when homes are completely heated and dried up from air, hardwood gives up some of its moisture and results in contracting your floors.When your hardwood floors starts contracting, thin gaps may appear between planks. Though it is quite usual with hardwoods, you should be prepared for it to occur, at the same time you should be little alert. Once the indoor heating is turned off and gets normal the humidity levels rise again, gaps between planks will close up gradually.
To avoid these separations on your hardwood flooring, try to control and monitor air humidity levels during the dry winters by installing a humidifier or a movable humidifier into the room that has good air flow or movement. Or installing a simple humidity meter will allow you to monitor and control humidity levels in your home all year round. Optimal humidity level varies in between 45-60% range. As long as humidity is above 45%, no gaps will appear between the planks of your hardwood.
Chances for hardwood cupping- The first and foremost things to do once you notice cupping on your hardwood floor is to identify and eliminate the moisture source.
The problem with cupping could be flooding, plumbing leak in the basement or indoor humidity level may be increased or decreased.Once the moisture source is eliminated or rectified, cupping is usually easy to fix on your hardwood flooring.
If cupping is at extreme from normal mode, then hardwood floor needs to be sanded and refinished completely. Be assured that the floor has thoroughly dried up before sanding it. If cupping is moderate, the floor improves on its own as it dries eventually.
Moisture and Exotic Wood Species-
Wood Flooring is manufactured from domestic woods from timber that is designed for use as flooring. For this reason, a set of additional requirements has to be maintained while installing an exotic hardwood floor. Indoor air humidity level should be always in the range of 50-70% of comfortable relative humidity, and air temperature should be kept in the range of 18-24 °C.In order to meet these needs with installed hardwood, set up an air humidifier during the dry winter season and heat the room. During humid summers use AC to maintain acceptable humidity on your hardwood.
It is recommended to buy a combined digital temperature/moisture meter in order to monitor indoor conditions all year round.