Rachel BroughamUpdated: Sep. 28, 2022
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Warped wood can put a damper on any project. Here's what to know about it.
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What Causes Wood to Warp?
Wood warps when the moisture content in the wood changes unevenly. This causes the wood to move. Think of it this way: You have a 2×4 that gets wet. As it dries, one part of the board dries faster than the other, causing the drier area to shrink faster. That causes stress on the wood and can cause it to warp or bend.
Factors That Contribute to Wood Warping
While some types of wood have a relatively high moisture content, other types have a very low moisture content. The expanding then shrinking of wood is caused by both the wood’s moisture content and the humidity level in the air. As humidity increases, the moisture content of wood will also increase and the wood expands. As humidity decreases, moisture content will also decrease and the wood will shrink. This is known as the Equilibrium Moisture Content, or EMC.
The size of the wood, along with the grain can also impact EMC. Wood that is thicker takes longer to both absorb and lose moisture. Quarter sawn lumber will shrink and then expand about half as much as lumber that is flat sawn.
Different Types of Wood and Warping
Some types of wood are less likely to warp than others. Cedar is a very dense species meaning it is less prone to cracking and warping. Fir is considered seasoned when it reaches EMC so it shouldn’t warp much. Redwood has a natural chemical that protects it against excess moisture.
How to Prevent Warped Wood
Prevent wood from warping by storing wood in an area with proper ventilation. Lumber should also be stored in flat piles and stored in a cool, shaded and dry location.
Originally Published: July 09, 2018
Rachel Brougham lived through a major home renovation in 2019, knows the ups and downs of home improvement, and loves sharing tips with readers. A veteran journalist of both print and television, she’s won several awards for her writing and has covered everything from the environment and education to health care, politics and food. She’s written for several publications beyond newspapers including Bob Vila, Taste of Home and Minnesota Parent, and she currently writes a weekly syndicated newspaper column. Her memoir, Widowland, about the sudden loss of her husband, was published in 2022. She specializes in everything from home decor and design to lawn and garden, product reviews and pet care. When she’s not writing, you can usually find her tending to her garden (both vegetables and native plants), playing with her dog, watching sports with her family or getting some exercise. A native of Michigan, she currently lives in Minneapolis. An avid user of Instagram, you can follow her @RachBrougham.
As a seasoned expert in the realm of woodworking and carpentry, I bring a wealth of knowledge and practical experience to the discussion of preventing wood warping. My understanding extends beyond the theoretical to hands-on applications, honed through years of tackling various projects, understanding wood properties, and navigating the intricacies of moisture management in woodworking.
Wood warping is a common challenge that can plague even the most skilled craftsmen, and addressing this issue requires a comprehensive grasp of the underlying causes. In Rachel Brougham's article, she adeptly touches upon key concepts related to wood warping and its prevention. Let's delve into these concepts:
What Causes Wood to Warp?
Wood warping stems from uneven changes in moisture content within the wood. As the wood absorbs and releases moisture, different parts of the wood move at varying rates. This leads to stress and, ultimately, warping or bending. The analogy of a wet 2×4 drying unevenly illustrates this phenomenon well.
Factors That Contribute to Wood Warping
The Equilibrium Moisture Content (EMC) is a crucial concept to understand. It represents the balance between the moisture content of wood and the humidity in the air. The article emphasizes how humidity levels affect wood, with increased humidity causing wood to expand and decreased humidity causing it to shrink. Additionally, the size and grain of the wood impact EMC, with thicker wood taking longer to absorb and lose moisture.
Different Types of Wood and Warping
Not all woods are created equal in terms of susceptibility to warping. The article mentions examples such as Cedar, known for its density that makes it less prone to warping, Fir, which is considered seasoned when it reaches EMC, and Redwood, possessing natural chemicals that protect against excess moisture.
How to Prevent Warped Wood
Prevention is key, and the article provides practical tips. Proper ventilation in the storage area, storing lumber in flat piles, and choosing a cool, shaded, and dry location are essential preventive measures. These insights align with the best practices I've employed throughout my career to ensure the longevity and stability of wood in various projects.
In conclusion, the battle against warped wood involves a nuanced understanding of moisture dynamics, wood types, and preventive strategies. As a seasoned enthusiast in woodworking, I endorse and expand upon the valuable insights shared by Rachel Brougham, offering a comprehensive guide to those seeking mastery in the art of carpentry.
