Softwood lumber

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What is softwood lumber?

British Columbia (B.C.) softwood lumber product lines include spruce, pine, cedar, hemlock, larch and fir species. Softwoods come from conifer trees or cone-bearing trees, and B.C. softwood species have needle-shaped foliage instead of the leaves found on hardwood trees.

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Types of lumber

Dimension lumber refers to the standard pre-dimensioned wood used in wood-frame construction, including walls, floors and roofs. 1.5 inches thick and of various lengths and widths, it is the structural softwood lumber used in most wood-based housing construction (platform-frame construction) in North America.

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Where great strength is critical, such as in truss rafters, machine stress-rated and machine-evaluated lumber offers consistent performance. Machine grading measures a desired characteristic—such as bending strength or density—and ensures that the graded lumber is more precisely selected than is possible with visual grading.

The Confluence | Photo credit: Matthew Bolt Photography

Low-angle shot of construction worker on wood trusses above against a blue sky.

Timber refers to a finished wood product with a minimum dimension of 5.5 inches. Often used in post-and-beam construction and remanufacturing, it is valued for its architectural beauty and structural capacity.

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Non-structural, finished product used to manufacture desks, shelving, furniture etc. Produced as a 3/4-inch thick material in various widths and lengths; usually dried and planed smooth.

Kiln-dried lumber is recommended as freshly sawn (or green) lumber is often too high in moisture content for some uses. Kiln drying before the lumber is shipped reduces moisture content and increases the wood’s structural integrity, appearance, and workability, as well as reduces swelling or shrinkage. Lumber is typically kiln-dried to a moisture content of 19 per cent or less.

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Classification of lumber

Lumber manufacturing classifications consist of rough dressed (surfaced) and worked lumber. Rough lumber has not been dressed but has been sawed, edged, and trimmed. Dressed lumber is rough lumber that has been planed on one or more sides to attain smoothness and uniformity. Worked lumber, in addition to being dressed, conforms to a specific pattern, is matched or shiplapped. Matched lumber is tongue and groove, either sides or ends or both. Shiplapped lumber has been rabbeted on both edges—that is grooves cut into the edges—to provide a close lapped joint. Patterned lumber is designed to a pattern or molded form.

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Grading for consistent quality and reliability

Structural framing products are graded for their strength and other physical properties, as opposed to appearance products, which are graded for their aesthetic properties. A lumber grade is a minimum standard describing the characteristics allowed in a piece of lumber. Each piece of lumber is assigned a grade based on its quality (external link), using a rule which considers the intended use of the piece, the size of the piece, its quality, and in some cases its species. The National Lumber Grades Authority’s Standard Grading Rules for Canadian Lumber is a list of the permitted characteristics within each grade of dimension lumber.

Photo credit: Michael Bednar