Western Red Cedar (WRC) is botanically classified as a softwood, despite its reputation for durability and strength. This classification is based not on physical hardness, but on the type of tree it originates from. The tree, scientifically known as Thuja plicata, is a cone-bearing, evergreen gymnosperm, placing it in the same category as pines and firs. The true distinction between softwoods and hardwoods lies entirely within the cellular structure of the tree.
Understanding Botanical Wood Classification
The terms “hardwood” and “softwood” are botanical categories that define the reproductive structure of the tree, entirely separate from the wood’s physical density or durability. Hardwoods come from angiosperm trees, which are typically broad-leafed and deciduous. Softwoods originate from gymnosperm trees, which are cone-bearing, usually evergreen, and have needles or scales.
The defining difference is visible only under a microscope, concerning the cells that transport water and nutrients. Hardwoods feature a complex cellular structure that includes specialized water-conducting tubes called vessels or pores. These pores often create a distinct, open grain pattern in the finished lumber.
Softwoods, including WRC, possess a much simpler and uniform cellular structure. Approximately 90 to 95 percent of the wood is composed of longitudinal tracheids, which are elongated cells that serve the dual function of water transport and structural support.
Western Red Cedar’s Unique Physical Attributes
The source of the common misconception about WRC is its physical performance, which far exceeds that of many other softwoods. One of its notable characteristics is its low density, making it one of the lightest commercial softwoods available. At 12 percent moisture content, its density is approximately 23 pounds per cubic foot. This lightness results from its cellular structure, which contains a high proportion of air spaces, also providing excellent thermal insulation properties.
WRC’s exceptional durability stems from natural chemical compounds present in the heartwood. These extractives include thujaplicins, which function as natural fungicides, and thujic acid, which helps resist insect attack. This inherent resistance to decay and rot allows WRC to be used outdoors without chemical treatment.
Despite its durability against the elements, WRC is physically soft, registering a low 350 lbf on the Janka hardness scale. This low hardness means the wood is susceptible to dents and scratches compared to dense hardwoods like oak. However, the wood also boasts superior dimensional stability compared to many other coniferous species, showing minimal shrinkage and resistance to warping, twisting, and checking when exposed to moisture fluctuations.
Selecting WRC for Construction and Design
The combination of its low density and straight grain makes Western Red Cedar highly desirable for construction and design applications where workability is important. It is exceptionally easy to cut, saw, and nail, making installation faster and less taxing on tools compared to denser woods.
WRC’s resistance to weather and decay positions it as a premier choice for exterior projects, such as siding, decking, fencing, and outdoor furniture. Its performance in these roles often surpasses that of many physically harder woods that lack the same natural fungicidal extractives. The wood is free from pitch and resins, which allows it to readily accept a variety of finishes, including stains, oils, and sealants.
While WRC is not suitable for high-traffic flooring or applications requiring extreme surface hardness, its aesthetic qualities—ranging from amber to reddish-brown tones—and its dimensional stability make it valuable for interior features like paneling. Maintenance is minimal to preserve its structural integrity, though regular cleaning and re-sealing help maintain its natural color against the graying effects of UV exposure.