Wood flooring is an incredibly beautiful flooring material. When installed properly, they can add elegance and class to a structure. However, flooring installers need to carefully monitor the moisture content (%MC) of the wood flooring systems that they work with to prevent issues like cupping, warping, and cracking.
As a hygroscopic material, wood will absorb or let off moisture until it reaches equilibrium with the ambient humidity of the environment it’s currently being stored in. The moisture content at which the wood stops absorbing or letting off moisture is called the equilibrium moisture content (EMC) of the wood.
However, EMC values for wood can vary from one part of the country to the next. This is because of differences in ambient humidity and temperatures. Also, the time of year can have an impact on when wood reaches equilibrium, as temperatures and humidity levels change.
Wood EMC Values in Different States
North Carolina State University has a spreadsheet detailing the average EMC of wood in different parts of the country at different times of the year.
Some of the EMC values for wood in the U.S. noted in the document are:
|
City/State |
January |
April |
July |
October |
|
Phoenix, AZ |
8.9 |
6.0 |
6.2 |
6.9 |
|
Fresno, CA |
15.8 |
10.3 |
7.4 |
9.8 |
|
Denver, CO |
10.1 |
9.1 |
8.0 |
9.1 |
|
Miami, FL |
13.5 |
12.2 |
13.4 |
13.8 |
|
Atlanta, GA |
13.3 |
11.8 |
13.4 |
12.9 |
|
Chicago, IL |
14.3 |
12.4 |
12.7 |
13.2 |
|
Boston, MA |
12.1 |
11.5 |
11.8 |
12.6 |
|
Albany, NY |
13.7 |
11.2 |
12.2 |
13.7 |
|
Austin, TA |
13.3 |
13.0 |
12.6 |
12.8 |
|
Seattle, WA |
16.3 |
13.6 |
12.0 |
15.7 |
The full chart on the NCSU website has more listings that can help you get an idea of the ambient moisture conditions in your area.
Why Ambient Humidity Matters
Although most wood flooring is installed in interior locations with climate-controlled environments, the ambient humidity in your region can still affect the EMC value of wood. Knowing the EMC value of wood in your area can help you prepare your flooring for transport to the installation site.
Checking Wood Prior to Installation
Before installing a wood flooring system, it’s important to test the moisture content of the wood to see if it has reached EMC with the surrounding environment.
First, make sure that any climate control systems at the installation site have been turned on and set for their normal use settings for 72 or more hours.
Then, use a thermo-hygrometer to test the relative humidity conditions at the installation site. Record the temperature and the RH percentage given on the display.
Finally, take a moisture reading from your wood flooring and compare it to the EMC chart above. This should tell you if your flooring wood has reached equilibrium with the installation site or not.
If you do not have a thermo-hygrometer to test the relative humidity and temperature of the installation site, then you can take multiple moisture measurements of the wood flooring over the course of a few days. When the %MC of the wood stops changing from one reading to the next, then the wood has reached equilibrium.
Need more help with using moisture meters for flooring? Or, are you looking for the right tools to help you complete flooring installation jobs faster, easier, and with reduced risk of call-backs? Contact Delmhorst Instrument Co. today! We all look forward to helping you answer your questions about flooring moisture meters.
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