Moisture Content in Wood: How It Affects Your Desktop
Learn how Equilibrium Moisture Content (EMC) dictates whether your wood furniture will warp, crack, or stay flat.
Giang Nguyen
Wood Manufacturing Expert
Equilibrium Moisture Content (EMC)
Equilibrium Moisture Content (EMC) is the moisture level where wood neither gains nor loses moisture to the surrounding atmosphere. This level is determined solely by the relative humidity (RH) and temperature of the indoor environment.
Target EMC for Indoor Furniture
For indoor furniture, desks, and shelving, the industry standard target moisture content is 6% to 8%.
Here is how relative humidity correlates with the EMC of wood at a standard room temperature of 70°F (21°C):
| Relative Humidity (RH) | Wood Equilibrium Moisture Content (EMC) |
|---|---|
| 20% RH | 4.5% EMC (Very Dry - Wood contracts, risk of splitting) |
| 35% RH | 6.9% EMC (Ideal range for homes) |
| 50% RH | 9.2% EMC (Average summer range) |
| 65% RH | 12.0% EMC (Humid environment - Wood expands) |
| 80% RH | 16.0% EMC (Extreme humidity - Risk of mold and warping) |
Testing Moisture Content
Woodworkers use moisture meters to measure the moisture level of wood before and during construction.
- Pin Meters: Measure electrical resistance between two pins driven into the wood. Highly accurate but leaves small holes.
- Pinless Electromagnetic Meters: Use radio frequency waves to measure moisture density without damaging the surface. Perfect for checking finished tabletops.
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