3.2:

Softwoods and Hardwoods

JoVE Core
Civil Engineering
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JoVE Core Civil Engineering
Softwoods and Hardwoods

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01:28 min

September 12, 2024

Softwoods and hardwoods, derived from different types of trees, are distinguished by their leaf structures and cellular compositions, each serving unique purposes in construction and manufacturing. Softwoods come from cone-bearing trees with needle-like leaves and are predominantly composed of longitudinal cells called tracheids and a smaller proportion of radial cells known as rays. Due to their cellular structure, softwoods are commonly used in construction for structural frames, sheathing, roofing materials, and exterior siding.

The moisture content in softwoods plays a critical role in their use. In living or newly cut wood, cell fibers, and cavities retain moisture. As the wood dries, the water in the cavities evaporates first, followed by the residual water in the fibers, causing the wood to shrink at what is known as the fiber saturation point, typically around 30 percent moisture for most softwoods.

Hardwoods, on the other hand, typically shed their broad leaves seasonally and have a more complex microstructure with a higher percentage of rays and two types of longitudinal cells: small-diameter fibers and large-diameter vessels or pores. This complex structure makes hardwoods suitable for making cabinets, furniture, paneling, interior decorative trim, and flooring. The grain of hardwoods is often finer and more intricate, making it visually appealing and highly valued for aesthetic purposes. In contrast, softwoods generally exhibit a rougher and simpler grain structure.