What is proper moisture content for wood flooring?

- Dec 12, 2019-

People like Wood flooring as it is elegant, durable, and practical.However, many people don’t know about is how easily their beautiful wood floors can be ruined by moisture. Too much moisture can cause hardwood flooring to swell and cup. Meanwhile, too little moisture can cause the flooring to shrink and crack.

If the moisture content of wood flooring isn’t right, then it can warp, buckle, or even delaminate, causing significant damage and ruining the aesthetic value of the flooring. To make sure that the moisture content of wood flooring is in the right range, many professionals use flooring moisture meters to test their wood flooring materials.

Wood is a hygroscopic material, constantly absorbing and giving off moisture until it reaches an equilibrium moisture content with its surroundings.

In short, the more humidity that is present in the air, the more moisture wood building materials, such as flooring, will absorb. This has a direct effect on how much wood flooring will expand after installation. As wood absorbs water, it will expand across the grain, which can cause it to swell, warp, and buckle.

By contrast, environments with less humidity tend to make wood lose moisture. Here, the wood will shrink across the grain, which can cause the wood to warp and crack.

For all intents and purposes, the ideal moisture of flooring wood will be the moisture content at which the wood reaches equilibrium with the installation environment. At this equilibrium moisture content (EMC), wood will stop absorbing or shedding moisture, which prevents some of the physical problems that can occur in wood flooring.

This chart highlights the ideal levels of moisture in wood at various temperatures and relative humidity (RH) levels:


In this chart, you can see a small highlighted section. These are the “safest” conditions for most types of wood—between 60 and 80 degrees Fahrenheit and 30% to 50% RH. Outside of these ranges, hardwood floors might start to experience adverse effects.