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Lumber

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Lumber is wood that has been processed into uniform and useful sizes.

2 By 4 Clue Stick
2 By 4 Clue Stick

In the United Kingdom, Australia, and New Zealand, people often call it timber or fine wood. It is used extensively for construction framing and finishing tasks like floors or window frames. In North America, the term lumber specifically refers to milled boards. In the United States and Canada, the word timber describes standing or felled trees. However, in Britain and Ireland, timber is used to describe both the trees and the boards.

Bellingham, Washington, harbor, filled with logs, 1972
Bellingham, Washington, harbor, filled with logs, 1972

To create lumber, logs are transformed through sawing, hewing, or splitting.

The most common method is using a rip saw. This method is economical because it allows for the use of lower-quality logs. Plain sawing involves cutting through a log without adjusting its position. This causes the grain to run across the width of the boards. Other methods include quarter sawing and rift sawing. These techniques ensure the annual rings are perpendicular to the sides of the lumber. Some wood undergoes re-sawing, which is the process of splitting a thick board into thinner, full-length pieces.

Lumber is categorized into different types based on its source and finish. Most lumber is softwood, which comes from coniferous species like pine, fir, spruce, cedar, and hemlock. In fact, 80% of all lumber is made from softwood. Hardwoods are also used, though they are more common for high-grade flooring or furniture. Lumber can be supplied as rough-sawn material or surfaced on its faces. Rough lumber serves as the raw material for furniture-making and other shaped items. Finished lumber is supplied in standard sizes for the construction industry. There is also re-manufactured lumber, which is processed for industrial or packaging uses.

Humans have been refining wood processing for centuries. In 1420, settlers in Madeira cleared large forests to grow crops. They used sawmills to process felled trees for shipment to the mainland. A major technological leap occurred in 1593. A Dutch windmill owner named Cornelis Corneliszoon invented the first wind-powered sawmill. This invention was revolutionary for the era. It made converting logs into planks thirty times faster than manual sawing.

Wood from victoria mountain ash
Wood from victoria mountain ash

Modern construction relies heavily on dimensional lumber. This is lumber cut to standardized widths and depths. Common North American sizes include 2x4, 2x6, and 4x4. In the Americas, these are often called "two-bys." While the names suggest specific measurements, nominal dimensions are actually larger than the actual finished sizes. This is because wood shrinks during drying and is reduced during planing to make it smooth. For example, a modern 2x4 is actually 1.5 inches by 3.5 inches. Historically, a 2x4 was much larger before these standards changed. In 1910, a typical finished board was 1 inch thick, but by 1956, dimensions had been reduced multiple times.

The longest board in the world (2002)
The longest board in the world (2002)

Because wood is a natural product, its quality varies significantly. Factors like knots, grain slope, and shakes affect its strength and value. To manage this, national standards were established to ensure safety. The American Lumber Standard began in 1924 to set specifications for dimensions and moisture content. Today, the American Lumber Standard Committee sets these rules in the United States. In Canada, the National Lumber Grades Authority maintains grading rules. These systems help builders know exactly what kind of strength to expect from their materials.

Treated timber
Treated timber

Lumber technology continues to evolve through new materials and engineering. Some structural lumber is now produced from recycled plastic and new plastic stock. This is known as plastic lumber. When fiberglass is blended into plastic lumber, it increases strength and fire resistance. Some plastic fiberglass lumber can achieve a class 1 flame spread rating of 25 or less. This means it burns more slowly than almost all treated wood lumber. Additionally, engineered wood products are used to provide more flexibility. These are made by binding wood fibers or veneers together with adhesives to create strong composite materials.

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🖼️ Images & Media (6)
File:Wood from victoria mountain ash.jpg
Wood from victoria mountain ash.jpg
File:Bellingham, Washington, harbor, filled with logs, 1972.jpg
Bellingham, Washington, harbor, filled...
File:L' usine de transformation de bois Kotkamills Oy à Kotka.jpg
L' usine de transformation de bois...
File:2 By 4 Clue Stick.jpg
2 By 4 Clue Stick.jpg
File:The longest board in the world (2002).jpg
The longest board in the world (2002).jpg
File:Treated timber.jpg
Treated timber.jpg
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