Common Lumber Terms

A B C D E F G H I J K L M N O P Q R S T U V W

A.
4/4 = 1” (inch) – It is common to express the thickness of cabinet grade lumber in quarters of an inch. Hence: 4/4 = 1” and so on up to 16/4 = 4”.

Against the Grain – A reference to the cutting direction; generally cutting perpendicular to the grain direction, across the grain.

Air-drying (AD) – Wood that has been dried naturally (but not completely) to have moisture content of about 18%. The lumber is typically piled in alternating layers separated by narrow sticks to allow air circulation around lumber with minimal stain.

Along the Grain – Cutting wood parallel to the grain direction.

Anchor – Piece of equipment that holds something in place, like a clamp or cable.

B.
Backing Board – The board remaining on faceplate after slicing veneer.

Band Sawn – Saw blade tooth markings (kerf) on face are at right angle to edge of board.

Bird Peck – A patch of distorted grain resulting from birds pecking; sometimes containing ingrown bark and mineral streaks from the holes.

Bird’s Eye – Small, decorative, circular figure commonly found in Hard Maple, and often sold in veneer form.

Board – Lumber that is two-inches, or more, wide and usually less than two-inches thick. Boards less than six-inches wide are also called strips.

Board Foot – A piece of lumber 1” thick, 12” wide and 1’, or its cubic equivalent.

Book Matched – Adjacent veneer sheets are opened like a book, matching the back of one sheet with the face of the next. Opposite slant of grain creates a light and dark effect.

Bow – A defective piece of lumber that has warped along its length.

Burl – A swirl or twist in the grain of the wood that does not contain a knot. Often highly sought after for unique veneer they yield.

C.
CLF – One hundred lineal feet.

Chatter Marks – Bumpy surfaced lumber.

Circular Sawn – Saw blade tooth markings are curved on face of board.

Clear Face Cutting – A cutting having one clear face and the reverse side sound as defined in Sound Cutting.

Close Grain – Wood with narrow growth rings.

Coarse Grain – “Rapid Growth” wood with wide growth rings.

Color Change – Most wood darkens after finishing if not constantly exposed to sun’s rays. (Walnut is an exception).

Conditioning in Kiln Drying – Obtaining the same moisture content in the “shell” or outside surface of the board as there is in the “core” or center of the board.

Cutting – A portion of a board or plank obtained by cross-cutting or ripping, or by both. Diagonal cuttings are not permitted.

Cupped – A convex board with one or both edges higher than the center. Cup is always to sap side.

D.
Decay – Disintegration of wood substance due to wood destroying fungi. There are many stages/ types of decay and rot.

Deciduous – The term given to broad-leaved trees which shed leaves annually, usually hardwoods. Example: Ash, Oak and Walnut.

Defects – The most common defects include knots, worm holes, bird peck (bark pockets), wane, stain, pith, checks, unsound burls, shake and split.

Delamination – The separation of veneers in plywood through failure of the adhesive.

Density – Wood weight per unit volume. Durability, hardness and toughness usually increase with density.

Dimension Lumber – Lumber cut or S4S to predetermined specific width (sometimes also to length) 1×4”, 2×4”, 2×6”, 4×4” – 8”, etc. (Note: both hardwood and softwood dimension lumber are often piece tallied and are S4S to 1/2” to 3/4” off nominal width and 1/4” to 1/2” off nominal thickness).

Dowel – A round pin or peg of wood used to fit together separate wooden units.

E.
End Check – A drying defect that causes separation of the wood fibers at the end of a board.

End Grain – Lumber grain as seen from one end of the board where elongated pores are exposed. End grain can absorb and release liquid and liquid vapors.

End Matched – Tongue and grooved on ends of boards as well as the sides (as in flooring).

Even Texture – Uniform texture showing little contrast between spring growth and summer growth.

Equalizing in Kiln Drying – Obtaining moisture content from board to board in a charge of lumber.

F.
Face – When a board has one side that is wider than the other, the wider side is referred to as the “face” (as opposed to the edge). It could also refer to the side visible in the finished product.

Fiberboard (MDF) – Panel board made from wood fiber or pulp bonded with adhesive; plywood substitute.

Fiddleback – A grain characteristic that has a rippled appearance. Widely used for musical instruments. (Maple, Mahogany and Sycamore).

Figure – Unusual wood grain pattern.

Flakeboard (Particle Board) – A board composed of wood flakes bonded together with a synthetic resin or other suitable binder under heat and pressure.

Flitch – 1) A hewn or sawed log or section of a log made ready for cutting into veneers by shaping up the edges; 2) After cutting a complete bundle of thin sheets laid together in sequence as they were sliced or sawn. 3) A thick piece of lumber without wane (bark) on one or more edges suitable for remanufacturing

Foot – Unit of measurement used to indicate the length of lumber. (1’ or 12”)

Framing – Lumber used for structural support; a skeleton to which floors, roofs and sides are attached. Often framing lumber is 2-4” thick and 2” wide, or wider.

G.
Grade – A designation of the quality of a log or wood product determined by a set of criteria including appearance, strength and suitability for various uses.

Grain – The lengthwise pattern of wood fibers. Among the many types of grain that exist are coarse, curly, fine, flat, open, spiral, straight and vertical.

Green Lumber – Freshly sawn; unseasoned; not dry. Lumber with a moisture content of 30% or more

Gross Tally (Green Tally) – The actual board feet measured before kiln drying. When kiln dried lumber is sold on this basis, the buyer can expect to receive approximately 7% less board feet because of shrinkage in the kiln drying process.

Growth Rings (Annual Rings) – New wood formed by the annual growth of a tree.

H.
Hardwood – The wood of any broad leaved tree bearing its seeds in a closed cavity. This term does not relate to the density of the wood.

Heartwood – The central supporting column of the tree trunk, consisting of matured wood in which little further change will occur. Usually harder and darker than new wood.

Honeycombs – A cellular separation that occurs in the interior of a board in the early stages of drying, usually along the wood rays, appearing as deep, internal checks.

I.
Improved Wood – A type of lumber made by soaking hardwood veneers with synthetic resins. Heat and pressure produce a strong durable product much heavier than natural wood.

Inlay – A design in the surface of furniture formed by inserting other woods and materials of different color or composition.

J.
Janka Hardness Test – Measures the resistance of wood to denting and wear. The resulting Janka hardness rating is used to determine whether a species is suitable for certain uses, such as flooring.

K.
Kerf – The path/ groove that any saw makes in the process of cutting.

Kiln-Drying – Artificial method of drying lumber by forcing heated air to circulate around the lumber in an enclosed building.

Kiln-Dried (KD) – Wood that has been artificially dried. Typical moisture content is 8% or less in hardwoods and 13-19% in softwoods.

Knot – A circular, woody fiber in a board that once formed the base of a branch or twig growing from the trunk of a living tree. There are several classifications of knots, including encased, loose, pin, sound and spike knots.

L.
LFE – Low Formaldehyde Emission

Lineal Feet (Lin.Ft.) – A measurement of the length of the board. One lineal foot is one foot in length, regardless of width or thickness.

Live Load – The amount of weight any structure is designed to support.

Lumber – Logs that have been sawn, planed and cut to a length.

  • Factory and Shop Lumber – Lumber intended to be cut up for use in further manufacture.
  • Matched Lumber – Lumber that is edge dressed and shaped to make a close tongued-and-grooved joint at the edges or ends when laid edge to edge or end to end.
  • Nominal Size – As applied to lumber, the size by which it is known and sold in the market, often differs from the actual size.
  • Patterned Lumber – Lumber that is shaped to a pattern or to a molded form in addition to being dressed, matched, or shiplapped, or any combination of these workings.
  • Rough Lumber – Lumber that has not been surfaced but has been sawed, edged, and trimmed.
  • Shiplapped Lumber – Lumber that is edge dressed to make a lapped joint.
  • Side Lumber – A board from the outer portion of the log; originally one produced when squaring off a log for a tie or timber.
  • Structural Lumber – Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.
  • Surfaced Lumber – Lumber that is dressed by running it through a planer.
  • Yard Lumber – Lumber of all sizes and patterns that is intended for general building purposes having no design property requirements.

Luster – Reflection of light sheen on wood surface.

M.
MBF – Thousand board feet.

Maple (soft/hard) – The term “soft maple” is used to distinguish the softer species of maple from the harder species. Soft Maple is a broad term which includes many different species, but Hard Maple typically only refers to one specific type of maple, commonly known as Sugar Maple.

Marquetry – An inlaid work of wood made from many different veneers. Used for decorative application.

Medullary Rays – Radial vertical tissues, extending across the growth rings of a tree, that enable the transmission of sap and produce a decorative, spotted figure in quarter-sawn boards. Often seen in mahogany.

Millwork – Lumber that has been “manufactured” by being run through such milling machines as a planer, straight line rip, etc.

Mineral Streak – An olive to greenish-black or brown discoloration of undetermined cause in hardwoods. Often accompanied by worm holes.

Moisture Content – Percentage of moisture present in wood.

Moulding – Long strips of wood which have been shaped to contours for ornamentation. / Small shaped lengths of wood used for both interior and exterior trim.

N.
NHLA – National Hardwood Lumber Association

Net Measure – The actual measurement of hardwood lumber after kiln drying with no addition of footage for kiln-drying shrinkage and includes tongue or lap

Non-Commercial Species – A tree species in which small size, poor form or inferior quality is typical, so these species do not normally develop into trees suitable for conventional wood products.

O.
Open Grain – Hardwoods with widely separated annual rings and large pores.

P.
Parquet – A geometric pattern of wood floorings.

Peck(y) – Localized patches of disintegrated wood on the board surface caused by decay on the living tree (most common to Bald Cypress).

Pitch – A resinous, gummy substance in firs and pines. / the number of teeth on a saw blade per inch.

Pitch Pockets – Defects resulting from resin accumulated between the growth rings in softwoods.

Pith – The small soft center core of a tree.

Plain (Flat) Sawn – Lumber sawn tangent to the tree’s annual rings. Most lumber is Plain Sawn. Advantages in Plain Sawn: (1) less costly and wasteful, hence more available (2) easier to kiln dry (3) averages wider widths.

Planed – Machine dressed to a smooth surface.

Plasticity – The property that describes a wood’s ability to retain its shape when bent (see Toughness).

Plywood – Sheet stock made from layers of veneers or plies, glued together with grain alternating in direction to counteract shrinkage and warpage.

Porous – This term refers to hardwoods only as all softwoods are non- porous. Typical woods are generally “diffuse porous” because growth is uniform throughout all seasons. By contrast, Oak is “ring porous” since the “spring growth” is softer and coarser than the summer growth.

Pulp – Wood fibers, ground and suspended in water, from which paper is made.

Q.
Quarter-Sawn – A method of cutting lumber where the annual rings are relatively perpendicular to the face of the board. Advantages in quarter sawing: lumber is more dimensionally stable due to reduced shrinkage, twisting, checking, cupping and splitting.

R.
Random Widths and Lengths (RW&L) – Hardwood lumber is cut to yield the maximum of usable material and minimize waste. Both widths and lengths are, therefore, random and even the best grades allow occasional defects.

Resin – A vegetable liquid or semi-liquid exudes from certain species of trees, particularly the pine tree. Pine resin is the source of naval stores.

Rift-Sawing – Rift-sawing is midway between quarter -sawing and plain sawing. It offers the same figure consistency as quarter-sawing but develops a more subtle grain figure.

Rip-Cut (Ripping) – A cut made parallel to the grain of the board.

Rough (RGH) – The board surface as it comes from the saw.

S.
SLR1E – Straight line ripped one edge to give one true glue edge.

S2S – Surfaced (machined to a smooth finish) on two sides with rough edges

S4S – Surface (machined to a smooth finish) on all four sides.

SND – No sap defect.

Sapwood – The lighter-colored wood growing between the heartwood and bark.

Seasoning – Reduction of moisture content of wood to lighter weight and increased stability.

Second-Growth Timber – The trees that come up naturally after the first growth of timber has been cut or destroyed by fire.

Selective Cutting – Method of timber harvesting in which certain trees are cut for specific purposes.

Shake – A lengthwise separation of the wood occurring before the timber is cut into lumber, usually resulting from violent storms or in felling the log.

Shorts – High quality lumber shorter than standard grade (less than 6 feet long).

Shrinkage – Decrease in the volume or dimension of wood as a direct result of the drying process. Plain sawn boards will usually shrink twice as much as quarter-sawn.

Skip Dressed – An area on the board missed by planer surfacing knifes, giving a surfaced side a rippled or wavy effect.

Softwood – The non-porous wood of any cone-bearing, needle leaved tree, regardless of whether the wood is hard or soft.

Sound (Wood/ Cutting) – A board with no or very few defects which will affect its strength.

Sound Knot – A knot which is solid across its face, as hard as the surrounding wood, and shows no indication of decay.

Square Foot – An area 12×12” or the equivalent of 144 square inches without regard to thickness.

Stain – A finishing substance for coloring wood or discoloration in lumber caused by decay, fungi etc. normally avoidable through proper handling in the cutting and drying stages.

Steamed – This term refers to a special process in which the green lumber (usually walnut or cherry) is steamed in vats for the purpose of darkening sapwood to blend with heartwood color. Schutte Lumber’s beech wood is steamed.

Straight Grain – The board’s principal wood grain runs parallel to its length.

Straight Line Ripping (SLR) – Produces a perfectly straight edge that is ready for gluing.

Stripe – A grain pattern often seen in tropical hardwoods caused by the spiral growth formation in the trunk.

Surface Check – A drying defect that occurs when the surface dries too quickly in relation to the core, causing the separation of the wood fibers producing small, shallow, lengthwise separation of wood along the board’s surface.

Surface Measure (SM) – Measuring method used for hardwood grade inspection. Same as square footage.

Surfacing – The way a piece of lumber has been prepared at the lumber mill. See S2S, S4S, etc.

T.
Timber – General term applied to a forest and its products. Sawed lumber more than 4×4 inches in breadth and thickness.

Tolerance – Judgmental decisions for acceptable “give or take” variance from rules and dimension specifications.

Tongue and Grooved (T&G) – Tongue and grooved on sides of board so that the tongue edge of one board fits into the grooved edge of the next board.

Tongue and Grooved & End Matched (T&G&EM) – Tongue and grooved on both sides and at both ends of piece, as in Oak flooring.

Torn Grain – A defect in which fibers below the dressed surface are torn by the planer or cutters.

Toughness – The property that allows wood to absorb a relatively large amount of energy, withstand repeated shocks and bend without breaking (see Plasticity).

Twist – Spiral warpage of a board where the ends twist in opposite directions.

U.
Uneven Grain – Wood in which the growth rings deviate in width.

Uneven Texture – Wood which has considerable contrast between spring and summer wood (see Porous).

V.
Veneers – Sliced or peeled thin sheets of wood for gluing to other veneers or to some other base material. Most hardwood veneers are used for decorative purposes.

Vertical Grain (VG) – A softwood term meaning the grain on quarter sawn boards ; close ring grain.

W.
Wane – The presence of bark, or the lack of wood from any cause, on the edge or corner of a piece of lumber.

Warp – Distortion in which board turns or twists out of shape. Especially prevalent in woods of uneven density, e.g. sapwood and heartwood of contrasting hard-soft annual growth. Also results from applying finishes, veneers, laminated plastics, etc. to one side of the piece only.

W.H.A.D. – Worm holes a defect.

W.H.N.D. – Worm holes no defect.

Worm Holes – Voids in the wood caused by the burrowing action of certain wood-infesting worms which do not survive the kiln-drying process.

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