How Moisture Affects Wood

In nature, wood is a resource that was designed to perform in a wet environment, absorbing and losing water to balance its moisture content. All wood is hygroscopic, meaning that when exposed to air, it will release or pick up moisture until it is in equilibrium with the humidity and temperature of the air. Because of this, wood tends to expand as it gains moisture and to shrink as moisture is lost, and it does not shrink or swell equally in all directions. Any solid wood or wood component will expand or contract over time as moisture and climate conditions change, and this exchange of moisture is ongoing. In an uncontrolled environment, wood is a dimensionally unstable material.

How Moisture Affects Wood PDF

Some wood species are more hygroscopic than others and the expansion and contraction is more pronounced. Just because a piece of wood is “finished,” that is coated with stain, sealer and top coat, it is not impervious to moisture. Much like a wood table will absorb water from a spill or have a moisture ring left on it from a drinking glass, cabinets will take in moisture through contact with liquids or absorption from the air.

Humid Climates

Wood products located in humid climates are especially susceptible to expansion due to the extra moisture in the air. The wood will absorb this moisture, causing it to swell or expand. If doors are exposed to excessive moisture for an extended period of time, they may not resume their original size.

Dry Climates

In low humidity conditions, wood will release moisture and shrink or contract in size. During winter in the colder areas of the country, cabinetry will shrink from the dry heat supplied from home heating units. As the wood loses moisture, gaps will appear at the joints between the cabinetry pieces. Painted doors will also reveal seams at the joints as natural wood movement occurs. As the cabinetry regains its lost moisture under humidification control or during the summer months, these gaps will often close and be less noticeable. This occurs with all wood products in the home – furniture, millwork and cabinetry.

What Can I Do To Help Avoid Moisture-Related Problems?

  • Proper climate control within the home can greatly reduce the occurrence of moisture-related problems.
  • Keep in mind that cabinetry in non-air conditioned or humidity-controlled homes in areas of high humidity will expand.
  • Remember that second homes should always be maintained with some type of climate control, even when not occupied.
  • Choose a wood species with a low dimension change coefficient for homes in areas of risk. (See Hygroscopic Characteristics of Wood Chart below.)
  • Humid areas should also avoid wood slab doors. Slab doors are constructed of solid pieces of edge-glued wood which can magnify the effects of expansion and contraction. A good alternative to this door style is a wood veneer door with solid wood edging.
  • To avoid potential problems, we recommend that you maintain the relative humidity in your home in the range of 40% to 50%. Extreme variations in humidity will cause problems. When changes in humidity are minor, the dimensional response of the wood will be insignificant.
  • The temperature in your home should also be maintained within a range of 60 - 90F. Cabinetry should not be too close or directly facing air vents or radiant heat sources.

Under normal fluctuations in temperature, you can depend upon your cabinetry to perform and look beautiful for many years. Our warranty does not cover damage from exposure to extremes in temperature or humidity, or product concerns related to improper control of humidity/moisture levels.