Wood Movement in Cabinet Doors and Drawers

Our manufacturing facility is located in Central Pennsylvania, where the relative humidity can be as high as 90% in the summertime. In addition to that, we have a heating season that starts in October and runs into late March to early April. Why am I telling you all of this? Wood is constantly susceptible to changes in moisture. Wood absorbs moisture, causing it to expand during high humidity seasons and contract in dry air conditions, like those caused by forced hot air and wood stoves. If the right measures aren't taken, this can negatively impact your cabinetry.

TAKING THE RIGHT PRECAUTIONS

From the very beginning, it is important to manage lumber and sheet goods. We take the proper precautions by purchasing wood at the recommended moisture content (MC). The recommended MC for hardwoods in our region is 6-8%. However, we to take even more precautions to ensure these cabinets are built to last. Doors that are built in five pieces are engineered with rubber stoppers that allow for expansion and contraction (see below).

Careful attention is also paid to the joints to ensure they are built for long term durability. The expansion and contraction issues we are talking about are limited to solid wood. Many of the substrates in today's market use a flat panel look. We would prefer to use a veneered MDF (medium density fiberboard) panel for this type of look. These MDF panels overcome the expansion issues of hard wood, as they will not expand or contract.

RELATIVE HUMIDITY CAN CAUSE WOOD TO MOVE

In fact, about 1% growth occurs for every 4% of change in relative humidity (RH). Most of this expansion occurs across the grain. These pressures are incredibly strong; joints can fail, stiles can warp, and panels can crack. Often any joint failure is due to the extreme pressure it is receiving from the panel.

WHAT ARE THE CAUSES OF HIGH HUMIDITY?

In general we think extreme weather; like rain and tropical storms bring the highest humidity. This can be true, but, lakes, ocean fronts, and even pools that are sometimes located right outside the kitchen can also raise the humidity in the space. On job sites, things like new concrete, plaster, and lack of doors and windows can cause a higher humidity as well.

You might be asking yourself, doesn't the finish seal the wood? Wood continues to breathe; sealer, topcoats and paints will not stop wood from expanding or contracting. If this is a concern for you, there are small, inexpensive MC meters and monitors available at big box stores.

WHAT IS RECOMMENDED RH?

At Plain & Fancy we monitor our RH and hold our winter internal values between 35-45% RH. However, in the summer, due to the tremendous amount of air flowing through our dust collectors, we cannot limit our humidity, making it a possibility that it could reach 90% RH. In most homes and offices it is typically less. Note, that air conditioning removes RH from the space. Most homeowners are generally comfortable if the RH is 32-40%. However in the winter the air may become too dry, especially in the northeast, where homes are built tight to keep out winter cold, and interior air is heated and dried by forced hot air, or pellet/wood stoves and some are even located right in the kitchen. If the air is too dry it should be treated with a humidifier, which introduces moisture into the air to maintain an RH of 35-45%.

Wood is a fantastic material. It is very workable, warm to the touch and beautiful to the eye. If engineered and manufactured correctly, your cabinets will last a lifetime. Be sure to maintain them properly and pay special attention to the environment in which they are kept.