Green Lumber vs Kiln Dried Lumber: Choosing the Right Wood for Your Project
When it comes to woodworking and construction, selecting the right type of lumber is crucial for a project’s success. Choosing green and kiln-dried lumber can significantly impact your work’s durability, strength, and longevity.
Understanding each type of lumber’s unique properties and applications and the importance of monitoring their moisture content will help you make informed decisions and ensure the highest quality results in your projects.
In the article, we’ll discuss:
- What is Green Lumber
- Green Lumber Uses
- Green Lumber
- What is Kiln-Dried Lumber?
- Kiln-Dried Wood
- Advantages of Kiln-Dried Wood
- The Importance of a Moisture Meter
Forestry, done well, combines science and nature, resulting in strong, durable wood. However, all wood species are harvested in the “green” condition, a term for the properties that behold wood in the wild.
What is Green Lumber?
Green lumber, also known as “freshly cut” or “undried” lumber, is wood in its most natural state. It results from freshly felled trees, hence its high moisture content.
Green Lumber Uses
Green lumber is often used for specific construction projects like framing, where the gradual drying and subsequent shrinking of the wood don’t cause significant issues.
Get to Know Green Wood
Many observers would be shocked at the high (“green”) moisture content (MC) of some wood species. Since trees comprise an autonomous ecosystem of water and nutrients, it stands to reason that sapwood (the layer next to the bark) is generally higher in MC than heartwood (inner wood which has died).
Sapwood distributes water and nutrition through a tree. The heartwood, or inner wood, becomes infiltrated with gums, resins, and other materials.
This makes it more resistant to moisture flow, and thus, heartwood usually requires longer drying times than sapwood. Sapwood and heartwood will affect the drying curves for each wood species.
A wood’s MC is also a dynamic exchange between the wood and surrounding air. When the air’s relative humidity (RH) rises, wood absorbs moisture; when the RH falls, wood releases moisture into the air.
This occurs naturally throughout a wood product’s lifespan, even after being harvested and kiln-dried for human use. Wood producers, builders, and consumers need not fret over such an organic, natural process. Still, a thorough knowledge of it will guarantee success with wood in all sorts of product applications.
The key to wood strength and performance over time is to dry the wood appropriately to its optimum MC depending upon the end product’s service conditions and the end product’s installation destination.
What is Kiln-Dried Lumber?
Kiln-dried lumber is green wood placed in kilns where heated air circulates to dry it out. This process reduces the wood’s moisture content to achieve equilibrium moisture content (EMC), enhancing the wood’s strength and structural integrity for building purposes.
There’s Kiln-Dried Wood
Wood in “green” condition must be kiln-dried in order to be used as construction-grade lumber for building purposes, for example. Lumber production is a complex process in which green timber is sawn, dried, and processed. The natural air-drying of lumber can be a long process, so oftentimes, lumber will be kiln-dried to speed the process along.
Kiln-drying is placing sawn lumber into kilns where heated air is circulated. The temperature and RH of the kiln are controlled for the purpose of reaching the wood’s equilibrium moisture content (EMC): a balance between the MC of the wood, and the RH of its surrounding environment, depending upon the end wood products application specifications.
Once the EMC is achieved, a wood’s MC can vary slightly in the surrounding environment’s RH without jeopardizing the end wood product’s strength and structural integrity.
Lumber producers deploy expansive and expensive wood MC control systems at all phases of wood production. Kilns are an integral part of the wood’s MC measurement and management process, as the kiln-drying procedure is where the green lumber is dried to its optimum EMC.
Advantages of Kiln-Dried Wood
On the other hand, kiln-dried lumber has numerous advantages over green wood. The kiln-drying process reduces moisture content, which minimizes the chances of shrinkage, warping, or swelling once the wood is in use. For indoor furniture, flooring, or structures with crucial stability, kiln-dried wood is a favorite among carpenters and builders.
The Importance of a Moisture Meter
A wood moisture meter is crucial in establishing and maintaining healthy wood MC levels at each stage of lumber production. A moisture meter is a device used to measure the amount of water in the lumber. By understanding the moisture content, builders can predict how likely the wood is to shrink, warp, or rot.
Using a pinless moisture meter ensures you’re using wood at its optimum moisture level, ultimately extending the lifespan of your projects and preventing structural issues.
As green wood circulates for processing in a mill, in-kiln and in-line MC systems measure and document the wood’s MC and track the efficiency of the kiln-drying process. Professionals carefully monitor and control the process to optimize the harvest.
Kiln operators and quality control personnel deploy hand-held wood moisture meter products to conduct as many spot-checks as needed to verify the mill’s kiln-drying efficiency.
Wood moisture meter technology has advanced greatly as the world awakens to its own nature. Wagner Meters features its wood moisture meter products’. Now there’s a cost-effective, reliable wood moisture meter to suit any wood measurement application goal, from the home to the lumber-producing mills.
To learn more call: 800-634-9961.
Free Download – How to Choose the Right Industrial Hand-held Moisture Meter for Your Mill
Larry Loffer is a senior technician at Wagner Meters, where he has over 30 years of experience in wood moisture measurement. With a degree in Computer Systems, Larry is involved in both hardware and software development of wood moisture measurement solutions.
Last updated on July 19th, 2023