Why acclimate wood before installation?
Wood acclimation is a very important step in preparing for many years of beautify wood installations. Most people think of wood paneling and flooring as static, never moving or changing shape. The truth is that wood is hygroscopic, meaning that it is always either taking in moisture from the air or giving it back. This exchange mainly happens with seasonal changes. When wood gives up moisture, it shrinks and when it takes on moisture in a humid environment, it expands. Even though these contractions are very small, they must be taken into account when installing wood flooring or paneling into your home. If you fail to acclimate your wood properly, you can end up with unsightly gaps at the edges of your boards, or the wood can expand so much that it can create warping and wood failure.
The Process of Acclimation
First, ensure that the building is enclosed and maintained at normal living conditions for temperature and humidity. It does no good to acclimate flooring to interior conditions that are too moist or too dry, or in any way significantly outside the range of conditions likely to be found in the building after the flooring or paneling is installed.
Where building codes allow, permanent heating and/or air-conditioning systems should be operating at least five days preceding installation to promote proper acclimation. Where building codes do not allow for operation of the permanent system, acclimation of the flooring must be completed with the temperature and humidity maintained at or near normal living conditions, which generally fall between 60° to 80° Fahrenheit and at the average yearly relative humidity for the area.
If it is not possible for the permanent heating and/or air-conditioning system to be operating before, during and after installation, a temporary heating and dehumidification system using electric heating units, dehumidifiers and industrial fans can enable the installation to proceed until the permanent heating and/or air-conditioning system is operating.
Upon delivery, check the moisture content with a moisture meter to establish a baseline for required acclimation. If you don’t have a moisture meter, acclimate your wood flooring or paneling at least 5 days. Acclimation can be facilitated by breaking the floor units into small lots and/or opening the packaging. A common practice is to stack the flooring or paneling with ¾-inch to 1-inch sticks between each layer of flooring to allow air circulation on all sides of all boards like the picture.
Wood flooring is a hygroscopic material subject to dimensional change as a result of variations in moisture, temperature and humidity in the surrounding environment. That has led to increasing awareness of the need to properly acclimate wood flooring before installation. Wood flooring and paneling need to reach a moisture content level in equilibrium with the surrounding environment in which it will be installed, at or near normal living conditions. Always account for time of year and geographic location.
Not properly acclimating wood flooring may cause excessive expansion, shrinkage, dimensional distortion or structural damage. Most wood flooring and paneling failures can be traced back to improper acclimation.
The point of acclimating wood flooring before installation is to allow the moisture content of the wood to adjust to the installation site’s normal living conditions; that is, the temperature, humidity conditions and moisture content that will typically be experienced once the structure is occupied.
For site-finished wood flooring, after installation and before sanding and finishing, allow the flooring to acclimate to the controlled environment, and to stabilize for a period of time. The worst-case scenario is one in which wood flooring is stored at the jobsite in an uncontrolled environment — especially one that is subject to excessive moisture and humidity conditions. Garages, basements and exterior patios, for example, are not acceptable areas to store wood flooring.
As a general rule, with geographic exceptions, wood flooring will perform best when the interior environment is controlled to stay within a relative humidity range of 30 to 50 percent and a temperature range of 60° to 80° Fahrenheit..
For a more lengthy and technical guide to installing and acclimation of wood flooring and paneling, click on this link to the NWFA-Installation-Guidelines.