Understanding Wood Moisture Content

Wood needs time to settle once it is installed because all wood must adapt to its end-use environment. In moisture content (MC) terms, wood’s natural moisture levels need to reach equilibrium with its external surroundings before construction or installation begins. Unequilibrated MC in the wood product can give rise to continuous MC instability and ongoing moisture-related problems if that initial moisture balance was never achieved.

Equilibrium Moisture Content

Equilibrium Moisture Content (EMC) occurs when the MC inside wood reaches a balance with the relative humidity (RH) and temperature of the wood’s surrounding environment. This balance is crucial because wood continues to absorb and release moisture as the RH changes over time. On a humid, muggy day, wood can absorb moisture; on a dusty, dry day, wood can release moisture. For millennia, wood and its environment have interacted. So it continues to be. It’s as if nature and wood interact to keep moisture balanced in our world.

Wood strength and performance can be compromised by any MC imbalance, resulting in excess moisture. This is why lumber producers invest so much money in their kiln drying equipment and processes: to ensure quality control by drying the lumber to a specified target MC to ensure that the wood’s EMC is reached prior to shipping.

Builders and homeowners need to pay the same respect for wood’s need to acclimate to its surroundings upon delivery to its permanent home. Such respect is too often neglected in the rush of a busy schedule.

Permanent Settlement

Moisture meters for wood provide installers and homeowners the opportunity to easily and accurately monitor the wood’s MC. Wagner Meters has a variety of wood moisture meters for all levels of woodworkers and wood flooring experts. Orion^® Moisture meters can be used to measure the MC in all types of wood, including hardwoods, softwoods, and exotic tropical wood species. Woodworkers can utilize moisture meters to nurture those cherished wood projects to moisture equilibrium. Inspectors can detect moisture variations in several building materials, wood included. Moisture meters have evolved with technology, so users can measure and observe a material’s MC quickly and easily on a regular basis.

Ironically, the one wild card in the deck is human frailty. Wood manufacturers invest millions in MC measurement and management during the wood production process: kilns, in-line MC systems, and handheld MC spot-checks by the hundreds. Industry professionals understand that quality control begins with the arrival of green timber at the mill. However, too many builders and consumers presume that the quality control imperative is permanently assured by the lumber kiln drying process. Wrong.

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Wood needs time to acclimate to its environment once on-site also. Humans need to adapt to moist (or dry) conditions, and so does wood. Prior to installation, “permanent settlement” time is a prime time to measure the MC with moisture meters for wood. A wood moisture meter provides crucial evidence by which installers can ensure that the wood product has achieved its EMC state. Only with the confirmation of the wood reaching its EMC can users be assured of stable, long-lasting product strength and performance.

In the Long Run

Moisture meters for wood are also tools for the future of global environmental balance. Climate changes during the seasons of each region produce exactly the kind of weather fluctuations that can skew the MC in a wood product which has not equalized. Once the wood is safely installed, homeowners and hobbyists alike can use a wood moisture meter to continuously monitor the wood product’s MC for optimum long-term health.

As long as moisture is with us, human beings benefit from measuring it. Wood performance hangs in the numeric information provided by moisture meters for wood.

Troy Edwards

Troy Edwards is Technical Service Supervisor for Wagner Meters, Inc., where he oversees manufacturing, quality control and IT service for their electronic measurement products for the building and construction industry. Troy holds an AAS in Electronics Technology and has over 20 years’ experience in various electronic manufacturing and production positions.

Last updated on December 7th, 2021