By Kenn Garder, Corporate Accounts Manager, NPI/GPI Corporate Office
Hardwood flooring has been used for years; the flooring, if properly maintained, can last the lifetime of the building. The most common issues with hardwood flooring stem from moisture. Wood is a natural product and is considered hygroscopic; It gains and loses moisture as the relative humidity and temperature of the air around it changes.
To minimize moisture issues the hardwood floor manufacturer usually dries the lumber so it has a moisture content of 6 to 9 percent before milling into the flooring. The flooring should not be installed in rooms that are exposed to high moisture. It is recommended that the flooring be delivered to the site of installation and allowed to acclimate for up to 4 days in an area that has been climate controlled for at least 48 hours and the sub floor is dry. Following these recommendations is important to help minimize the amount of movement, but it’s not a guarantee that there won’t be issues caused by the changes in relative humidity.
Months and sometimes years after the floor has been installed and finished, moisture can still cause some visible issues.
Cracks and separation: When the room is heated in the winter the relative humidity decreases, shrinking the wood. This can cause the wood to separate resulting in cracks. To minimize these cracks moisture can be added to the air during the heating months.
Cupping: Wood flooring can cup or curl at the edges leaving the center lower, resulting in an uneven surface. The wood expands when the relative humidity is higher or if water is spilled on the wood’s surface and absorbed. As the wood expands, compression can result as the boards are crushed together deforming the edge of the boards. Humidity control will help the floor dry out and improve over time.
Crowning: This is the opposite of Cupping. The center of the board is higher than the edges. Crowning can occur if the wood is left exposed to high humidity or water for an extended period of time. Another cause is sanding a cupping floor before it is dry; as the cupped wood continues to dry the edges will shrink more than the center of the board.
Buckling: Because of excessive moisture, the flooring pulls up from the sub floor, lifting several inches from the sub floor. When the floor is flooded with water for an extended period of time, buckling can occur. A floor that has buckled will probably require more than drying out, typically, after drying out sections of the floor will need to be evaluated to determine if repairs can be made.
When these conditions are present in a hard wood floor, determine the water or moisture source and control or stop the moisture exposure to the wood. In hot humid weather using air conditioning and possibly a dehumidifier to control the relative humidity will help to reduce the movement in the floor.
With 10 years of experience in his current position, Kenn Garder is the central point of contact for NPI/GPI’s national accounts. He also provides technical support to our franchise owners/inspectors and teaches the commercial segment of our training program.
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