EMC – Equilibrium Moisture Content
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The numbers on the accompanying moisture map of North America provide examples of how average moisture contents for interior wood products vary from one region to another, and from one season to another within a region. Actual moisture content conditions in any region may differ significantly from these numbers.
Printed with permission from NWFA.
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Moisture Map North America
The EMC chart provides the correlation between moisture contents listed above and ambient relative humidity and temperature. Wood is stable at the given moisture and relative humidity ranges.
Here is an example: For most of the State of Florida the range (without an HVAC unit reducing the humidity) is listed as 12-13% wood moisture. The 12-13% moisture range is based on an average relative humidity between 65% and 75% for temperature ranges of 40°F to 100°F.
If the relative humidity is higher or lower, the moisture contents will change. Therefore the sentence above the map: Actual moisture content conditions in any region may differ significantly from these numbers.
The EMC Calculator.com lists values for any relative humidity, temperature and the corresponding stable moisture content.
Another example would be, someone moving from the coastal areas of California to the high desert of Nevada. Every piece of furniture is acclimated to the coastal conditions with relatively high humidity. Being exposed all of a sudden to very low relative humidity will dry out the wood from the surface towards the core. This alone can result in surface checking. Over time, every part of the furniture will follow and dry out. Glue lines may fail, delamination and other defects will appear. → Read more about shrinking…
Lignomat offers a line of meters to measure moisture and humidity. Measuring moisture and humidity is the first step in avoiding moisture problems. Because if you don’t know, how can you prevent. If you have a question, call Customer Service at 800-227-2105 or go to www.lignomat.com

Lignomat offers a wide selection of different moisture meters and thermo-hygrometers.
From the US Department of Agriculture Wood Handbook: “Wood as an Engineering Material”
Recommendations for relative humidity in buildings range from 30% – 50%.
Recommendations for ambient temperature in buildings range from 60°F – 80°F.
If ambient conditions stay within the recommended ranges, the moisture content of wood stays between 6% and 9%. The amount of expansion and contraction of wood is limited.
Examples:
1) Lumber at 7.7% will not change its moisture content if kept at a relative humidity of 40% and a temperature of 70°F.
2) Conditions in a warehouse are 60% relative humidity at 50°F. If dry wood is left in the warehouse for an extended period of time, the wood will pick up moisture until 11.2% wood moisture is reached, regardless of wood species and initial moisture content.
……………………..EMC Table
T | Relative Humidity | ||||||||||||||||||
°F | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 | 65 | 70 | 75 | 80 | 85 | 90 | 95 |
30 | 1.4 | 2.6 | 3.7 | 4.6 | 5.5 | 6.3 | 7.1 | 7.8 | 8.7 | 9.5 | 10.4 | 11.3 | 12.4 | 13.5 | 14.9 | 16.5 | 18.5 | 21.0 | 24.3 |
40 | 1.4 | 2.6 | 3.7 | 4.6 | 5.5 | 6.3 | 7.1 | 7.8 | 8.7 | 9.5 | 10.4 | 11.3 | 12.4 | 13.5 | 14.9 | 16.5 | 18.5 | 21.0 | 24.3 |
50 | 1.4 | 2.6 | 3.6 | 4.6 | 5.5 | 6.3 | 7.1 | 7.9 | 8.7 | 9.5 | 10.3 | 11.2 | 12.3 | 13.4 | 14.8 | 16.4 | 18.4 | 20.9 | 24.3 |
60 | 1.3 | 2.5 | 3.6 | 4.6 | 5.4 | 6.2 | 7.0 | 7.8 | 8.6 | 9.4 | 10.2 | 11.1 | 12.1 | 13.3 | 14.6 | 16.2 | 18.2 | 20.7 | 24.1 |
70 | 1.3 | 2.5 | 3.5 | 4.5 | 5.4 | 6.2 | 6.9 | 7.7 | 8.5 | 9.2 | 10.1 | 11.0 | 12.0 | 13.1 | 14.4 | 16.0 | 17.9 | 20.5 | 23.9 |
80 | 1.3 | 2.4 | 3.5 | 4.4 | 5.3 | 6.1 | 6.8 | 7.6 | 8.3 | 9.1 | 9.6 | 10.8 | 11.7 | 12.9 | 14.2 | 15.7 | 17.7 | 20.2 | 23.6 |
90 | 1.2 | 2.3 | 3.4 | 4.3 | 5.1 | 5.9 | 6.7 | 7.4 | 8.1 | 8.9 | 9.7 | 10.5 | 11.5 | 12.6 | 13.9 | 15.4 | 17.3 | 19.8 | 23.3 |
100 | 1.2 | 2.3 | 3.3 | 4.2 | 5.0 | 5.8 | 6.5 | 7.2 | 7.9 | 8.7 | 9.5 | 10.3 | 11.2 | 12.3 | 13.6 | 15.1 | 17.0 | 19.5 | 22.9 |
110 | 1.1 | 2.2 | 3.2 | 4.0 | 4.9 | 5.6 | 6.3 | 7.0 | 7.7 | 8.5 | 9.2 | 10.0 | 11.0 | 12.0 | 13.2 | 14.7 | 16.6 | 19.1 | 22.5 |
120 | 1.1 | 2.1 | 3.0 | 3.9 | 4.7 | 5.4 | 6.1 | 6.8 | 7.5 | 8.2 | 8.9 | 9.8 | 10.7 | 11.7 | 12.9 | 14.4 | 16.2 | 18.6 | 22.0 |