Vocabulary: Wood & Lumber

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Air-dried lumber

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lumber that has been seasoned by drying in the air

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Annular ring

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the rings seen when viewing a cross section of a tree trunk; each ring constitutes one year of tree growth

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Board

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lumber usually 8 inches or more in width and less than 2 inches thick

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Board foot

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a volume of wood that measures 1 foot square and 1 inch thick or any equivalent lumber volume

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Bow

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a type of warp in which the side of lumber is curved from end to end

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Cambium layer

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a layer just inside the bark of a tree where new cells are formed

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Check

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lengthwise split in the end or surface of lumber, usually resulting from more rapid drying of the end than the rest of the piece

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Close-grained

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wood in which the pores are small and closely spaced

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Coniferous

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cone-bearing tree; also known as evergreen tree

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Crook

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a type of warp in which the edge of lumber is not straight

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Cup

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a type of warp in which the side of a board is curved from edge to edge

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Deciduous

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trees that shed leaves each year

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Dimension lumber

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wood used for framing having a nominal thickness of 2 inches

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Dry rot

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dry, powdery residue of wood left after fungus destruction of wood due to excessive moisture

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Edge-grain

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boards in which the annular rings are at or near perpendicular to the face; sometimes called vertical grain

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Equilibrium moisture content

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the point at which the moisture content of wood is equal to the moisture content of the surrounding air

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Fiber-saturation point

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the moisture content of wood when the cell cavities are empty but the cell walls are still saturated

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Firsts and Seconds

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the best grade of hardwood lumber

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Grade

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the level of the ground; also identifies the quality of lumber

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Grain

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in wood, the design on the surfaces caused by the contrast, spacing, and direction of the annular rings

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Green lumber

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lumber that has not been dried to a suitable moisture content

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Hardwoods

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the wood of broad-leafed dicotyledonous trees (as distinguished from the wood of conifers)

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Heartwood

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the wood in the inner part of a tree, usually darker and containing inactive cells

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Juvenile wood

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the portion of wood that contains the first seven to fifteen growth rings of a log; they are located in the pith

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Kiln-dried

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lumber dried by placing it in huge ovens called kilns

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Knot

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a defect in lumber caused by cutting through a branch or limb embedded in the log

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Lignin

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the natural glue in wood that holds together the wood cells and fibers

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Lumber

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wood that is cut from the log to form boards, planks, and timbers

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Lumber grades

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numbers and letters used to rank wood according to quality

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Medullary ray

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bands of cells radiating from the cambium layer to the pith of a tree to transport nourishment toward the center

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Moisture content

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the amount of moisture in wood expressed as a percentage of the dry weight

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Moisture meter

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a device used to determine the moisture content of wood

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No. 1 common

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a lower grade of hardwood lumber

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Nominal size

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the stated size of the thickness and width of lumber even though it differs from its actual size; the approximate size of rough lumber before it is surfaced

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Open-grained

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a texture quality of wood where wood cells or pores are open to the surface

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Pitch pocket

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an opening in lumber between annular rings containing pitch in either liquid or solid form

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Pith

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the small, soft core at the center of a tree

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Plain-sawed

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a method of sawing lumber that produces flat-grain

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Quarter-sawed

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a method of sawing lumber parallel to the medullary rays to produce edge-grain lumber; see edge grain

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Sapwood

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the outer part of a tree just beneath the bark containing active cells

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Sawyer

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a person whose job is to cut logs into lumber

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Seasoned lumber

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lumber that has been dried to a suitable moisture content

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Shake

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a defect in lumber caused by a separation of the annular rings; also, a type of wood shingle

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Softwood

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wood from coniferous (cone-bearing) trees

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Stickering

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machine that makes moldings or a thin strip placed between layers of lumber to create an air space for drying

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Timber

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large pieces of lumber over 5 inches in thickness and width

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Twist

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lumber defect in wood

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Wane

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bark, or lack of wood, on the edge of lumber

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Warp

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any deviation from straightness in a piece of lumber