If you have noticed your wood door changing shape over time, this is due to warping. The root cause of wood warping is moisture. Moisture in the wood dries out unevenly, causing the wood to also shift unevenly.

How do you prevent wood from warping?

To prevent wood warping, ensure your stored wood is: In a well-ventilated area. In a cool, dry location. Not exposed to direct sunlight. Lying flat and slightly off the ground to prevent water damage.

Why Does Wood Warp?

If you have noticed your wooden door changing shape over time, this is likely due to warping. Wood warping occurs when wood loses moisture unevenly across its frame. As the moisture int eh wood dries out, i causes shrinkage, which results in a bend, twist or curve.

Wood is a hygroscopic material, so it can absorb or release moisture to achieve equilibrium moisture content (EMC) with its surrounding atmosphere. When loggers cut down trees, most woods will lose that free water relatively fast as they try to match the moisture content within their environments. This free water loss does not usually cause any problems for the wood.

Real challenges arise when the wood loses the water trapped within its fibers. Depending on the cut and storage area, wood may lose moisture faster on one side than the other. This varying drying process will form different kinds of deformation in the wood, more widely known as warping.

Some common types of wood warping are:

Crook: Occurs when one edge of the board dries and shrinks faster, causing an arched bend along the length of the edge of the board
Bow: Occurs along the length of the face of the board when drying causes the ends of the board to bend toward each other along its width.
Kink: Occurs along the width of the lumber when the board bends in one direction.
Twist: Happens when uneven drying causes one corner of the board to rise slightly higher than the other across the same length, resulting in a twisted appearance.
Cup: Happens when the board bends inward across the width, causing the edges along the length of the board to curl inward.

How to Prevent Wood From Warping

Common ways wood is warped arise from storage conditions. Factors like uneven finishing, changes in humidity, exposure to ultraviolet (UV) rays and high temperatures, coupled with thinly cut wood, all play a role in wood warping.

There are several proactive steps you can take to prevent wood warping.

Proper Storage

Good storage plays a significant role in protecting wood from warping and maintain its functionality. A good practice is to store wood ina dry, well-ventilated area. Limit exposure to direct sunlinght and ensure you boards are lying flat and slightly off the ground to prevent water damage. Additionally, place weights on wood boards to keep them straight, and put stickers-1-by-1-inch between the boards to allow for better ventilation.

Adequate Drying

Ensuring adequate during is one of the kye ways to prevent wood from uneven drying. Instead of relying on natural drying, some manufacturers use the kiln drying method to control the during conditions. Manufacturers can control factors like humidity and temperature over a even time in a kiln oven, ensuring even drying.

Space Acclimation

Even after drying, wood may still be affected by the humidity of its installation environment. A good warping prevention technique is to acclimate wood to the climate of the area where you will use it. Depending on the project, you can place wood within its final resting atmosphere for several days to get accustomed to the humidity level within the space.

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Can You Fix Warped Wood?

No — there is no reliable, foolproof method to fix a warped piece of wood and restore it to its former sturdiness. In general, if you are attempting to address warped wood, the wood needs to be wet down and then dried while in a flat position.

This technique can be achieved with irons and steam machines, but the process is complex and does not guarantee long-lasting, successful results.

What Type of Wood Is Best to Prevent Warping?

Choose durable wood to avoid malformations. The most durable wood:

Is stable under changing humidity, such as fir or pine.
Is dense, such as cedar.
Has a straight grain pattern, such as redwood.

The most stable doors are solid all the way through without a core and veneer. However, solid wood doors are usually more expensive and still do not guarantee you will entirely avoid warping.

We recommend a few other options:

Plastic laminate doors: Commercial plastic laminate doors have a composite core and are covered in durable plastic instead of a veneer, so there is no reason to worry about why wood warps with these door designs. Plus, you can still achieve a wood look through customization.
Metal doors: Installing high-quality metal doors have many benefits. They can help protect an interior from fires and break-ins, and their hollow core allows for great insulation and soundproofing. Metal doors are the most secure, durable and cost-effective option for many applications.

Select a Durable Commercial Door

For a more in-depth guide on wood strength, we recommend reading our article on door durability. Our experts at DoorStop can assist you in choosing materials for custom doors based on your clients' unique needs. With over 80 years of commercial door distribution experience, you can count on our expertise every step of the way.