“Water occurs naturally in living trees and affects wood properties and adhesive bond strength dramatically. Depending on extractives levels and wood chemistry, wood can typically take up 25% to 30% of its dry weight in water,” according to the U.S. Department of Agriculture. “The point at which wood cannot absorb any more water is called the fiber saturation point. As wood dries below the fiber saturation point, it begins to shrink and become stiffer. Above the fiber saturation point, excess water simply fills lumens and makes wood heavier.”
Also known as “dimensional changes,” the expansion and shrinkage that occurs with these fluctuations can wreak havoc, making controlling the MC (moisture content) critical during installation. A moisture meter can help you catch and correct conditions before they become a problem post-installation. They can be used to check the subfloor’s MC, water damage to the subfloor, and if the hardwood’s moisture level is at the correct level for the hardwood species.
There are two basic types of wood meters, pin and pinless. Pin meters actually penetrate the wood, while pinless types rely on sensors. Pin meters can leave blemishes, and can provide inaccurate readings if the pins aren’t properly inserted. Most pin moisture meters offer 3/4 to 1 1/2-inch reading depths, and are sufficient for hardwood flooring. However, if the flooring thickness is less than the pines meter’s reach, readings may be off.
As a general rule of thumb, test at least 10 boards per 1,000 sq. ft. and once for every 100 sq. ft. of subfloor, and pay special attention to areas that are naturally conducive to moisture. It’s also important to document your readings – not only as a reference, but also because it can help you spot climate trends that may impact the flooring immediately after installation and over time.
If you would like a referral for a moisture meter supplier or have more questions about MC, don’t hesitate to reach out to one of our technical experts. Meantime, here are common causes of high moisture meter readings to watch for: