What is balanced moisture content? Why is it important?
You may hear the term "EMC" mentioned from time to time in many different industries that involve the use of wood or other hygroscopic materials. Whilst industry veterans ± are very familiar with the term, it may not be familiar to those new to woodworking, flooring or restoration.
So what is EMC and why is it important to anyone who works with wood on a regular basis?
Defining EMC
The term "EMC" is an acronym for Equilibrium Moisture Content. The term is usually used for "hygroscopic" materials such as wood. The term "hygroscopic" refers to a material that absorbs moisture from the atmosphere or releases moisture into the atmosphere until it reaches equilibrium with its surroundings.
For the woodworking industry, equilibrium moisture content is defined as the point at which the wood stops absorbing moisture or releasing moisture into the surrounding air. At this point, the material is said to have reached equilibrium with the atmosphere.
So why is EMC important to carpenters, flooring contractors and restoration professionals±?
Why EMC is important
For those who work with wood products on a regular basis, there are several reasons why it is important to know that the wood reaches its EMC, which will be affected by the average moisture content of the area in which the wood is Used.
Firstly, when wood absorbs or releases moisture, it expands or contracts. The more moisture absorbed or released, the more severe the expansion/contraction of the wood product will be.
For example, let's say you're installing a set of wood flooring planks on a job site with an average moisture content of 11 per cent, which is indicative of a humid environment. However, the planks initially acclimatise to an area with an average moisture content of 6%, indicating a drier environment.
When exposed to a 'wet' environment, the boards will begin to absorb moisture from the air and expand slightly. This can cause installed planks to start cupping or warping as their expanding mass pushes against other planks - causing damage to the floor and ruining its appearance.
