Effects of Humidity on Wood

The Effects of Humidity on Wood

by Steve Gilman, Operations/Project Manager Builder Specialties Kitchen & Bath

Hardwood cabinetry parts such as face frames, doors, and drawer fronts are made from natural wood. It has great natural characteristics. However, natural wood also has some fundamental limitations that should be recognized. This is true of all wood-made products.

Unlike synthetic material, natural wood is not stable, meaning it will expand and contract under certain environmental conditions. Complicating matters further, wood will not expand and contract evenly. It does so across the grain rather than along the grain.  It can warp in some cases. Many cabinet companies include disclaimers in their warranty statements.

Wood naturally absorbs and releases moisture depending on the environment. Changes in the moisture content can result in dimension changes that can happen over time, or suddenly with season environmental changes in humidity. When these natural changes happen, joint lines can appear that were not seen before. As wood expands and contracts with seasonal humidity changes, a joint where a cabinet stile and rail meet can open up slightly. This will show a line that was not previously visible. When exposed to drier less humid air, door center panels will contract, exposing a visible line next to the stile until moisture is restored. These are natural characteristics of wood, are not considered defects, and thus are not covered under cabinetry warranties. Cabinet doors that are inset in door frames can be especially an issue in environments that experience extreme seasonal changes.

The most important thing you can do is stabilize the humidity in the home. Heating systems dry out the air in the winter, causing the wood to contract. Taking steps to maintain proper relative humidity year-round will keep your cabinetry more stable. Cabinet manufacturers recommend 30% to 55% relative humidity.

Air conditioning can help, as it removes some humidity from the air. But further steps, like a dehumidifier, may still be needed in some locations and climates.

Seasonal homes, especially those near water, should be heated and air-conditioned, even when not in use. Maintain a reasonable interior temperature of 55 to 75 degrees F.

If you want painted cabinetry, be prepared to see joint lines. If this is a major issue for you, choose an MDF door style.

Consider slab door styles with solid MDF cores and a veneered surface. They do not show joints and are quite stable.

Our best recommendation is to accept wood for its natural beauty and look at dimensional changes as another aspect of the distinctive personality of a lovely natural material.

Thanks for reading and at Builder Specialties Kitchen & Bath, we hope this helps you to understand a little more about your cabinetry.