Do you ever wonder as what does KD mean? or What is S4S? We know that all of the words that are used in describing wood decking and lumber can be very confusing. So we worked on providing this Glossary of Wood Words and decking terms for your reference. If there is anything that you think should be added please comment below. Also since this is a long list we recommend using the Control button + F (CTRL +F) command on your keyboard to search for your term on this page.
AIR DRIED (AD) Lumber that has been dried by exposure to air, usually in a yard, without artificial heat.
BEAM Any framing member placed to support a load.
BEVELED EDGE The chamfered, or angled edge of flooring, that creates a “V” groove when board edges are placed together, creating a more decorative display. A beveled edge is considered to be more of an indentation than an eased or micro-beveled edge.
BOARD FOOT (BD. FT. OR BF) The volume of a board 12″ long, 12″ wide, and 1″ thick or the equivalent (144 cubic inches of wood).
BURL A swirl or twist in grain of the wood, which usually occurs near a knot, but is not a knot.
CHECK A lengthwise separation of the wood that usually extends across the rings of annual growth and commonly results from stresses set up in wood during seasoning.
CONDITIONING The exposure of a material to the influence of a prescribed atmosphere for a stipulated period of time or until a stipulated relation is reached between material and atmosphere. Also referred to as “acclimating.”
CUP A distortion of a board in which there is a deviation from a straight line across the width of
DENSITY As usually applied to wood of normal cellular form, density is the mass of wood substance enclosed within the boundary surfaces of a wood-plus-voids complex having unit volume. It is variously expressed as pounds per cubic foot, kilograms per cubic meter, or grams per cubic centimeter at specified moisture content.
DRESSED Lumber that has been trimmed and planed at the sawmill.
FIGURE The pattern produced in a wood surface by annual growth rings, rays, knots, deviation from regular grain, such as interlocked and wavy, and irregular coloration.
GRAIN The direction, size, arrangement, appearance or quality of the fibers in sawn wood.
- CLOSE-GRAINED Wood with narrow, inconspicuous annual rings. The term is sometimes used to designate wood having small and closely spaced pores, but in this sense the term “fine textured” is more often used.
- COARSE-GRAINED Wood with wide conspicuous annual rings in which there is considerable difference between springwood and summerwood. The term is sometimes used to designate wood with large pores, such as oak, ash, chestnut and walnut, but in this sense the term “coarse textured” is more often used.
- CROSS-GRAINED Having fibers running irregularly from a line parallel to the sides of a piece of wood. Also referred to as “uneven” grain, cross-grained may be either diagonal, spiral, or a combination of the two.
- CURLY-GRAINED Wood in which the fibers are distorted so that they have a curled appearance, as in “birdseye” wood. The areas showing curly grain may vary up to several inches in diameter.
- DIAGONAL-GRAINED Wood in which the annual rings are at an angle with the axis of a piece as a result of sawing at an angle with the bark of the tree or log. A form of cross-grain.
- EDGE-GRAINED Lumber that has been sawed so that the wide surfaces extend approximately at right angles to the annual growth rings. Lumber is considered edge-grained when the rings form an angle of 45° to 90° with the wide surface of the piece.
- END-GRAINED The grain as seen on a cut made at a right angle to the direction of the fibers (e.g., on a cross section of a tree).
- FIDDLEBACK-GRAINED Figure produced by a type of fine wavy grain found, for example, in species of maple; such wood being traditionally used for the backs of violins.
- FINE-GRAINED Compact and smooth to the touch.
- FLAT-GRAINED Lumber that has been sawed parallel to the pith and approximately tangent to the growth rings. Lumber is considered flat grained when the annual growth rings make an angle of less than 45° with the surface of the piece.
- INTERLOCKED-GRAINED Grain in which the fibers put on for several years may slope in a right-handed direction, and then for a number of years the slope reverses to a left-hand direction, and later changes back to a right-handed pitch, and so on. Such wood is exceedingly difficult to split radially, though tangentially it may split fairly easily.
- OPEN-GRAINED Common classification for woods with large pores, such as oak, ash, chestnut and walnut. Also known as “coarse textured.”
- PLAINSAWN Another term for flat-grained lumber.
- QUARTERSAWN Another term for edge-grained lumber.
- SIDE-GRAINED Another term for flat-grained lumber.
- SPIRAL-GRAINED Wood in which the fibers take a spiral course about the trunk of a tree instead of the normal vertical course. The spiral may extend in a right-handed or left-handed direction around the tree trunk. Spiral grain is a form of cross grain.
- STRAIGHT-GRAINED Wood in which the fibers run parallel to the axis of a piece.
- VERTICAL-GRAINED Another term for edge-grained lumber.
- WAVY-GRAINED Wood in which the fibers collectively take the form of waves or undulations.
GRADE Term that defines the quality of the wood. The National Hardwood Lumber Association (NHLA) has set a standard grading scale. There are many criteria and restrictions, including number of cuttings, size of cuttings, and size of lumber.
- CLEAR GRADE Generic Term that refers to the highest grade such as First European Quality (FEQ) or Firsts and Seconds (FAS). The clear cuttings of a board may not have the following peculiarities that are considered a defect: bark pockets, bird pecks, checks, decay, rot, neither sound or unsound knots, splits, sticker stains, wanes, worm holes, piths or grub holes.
- FIRST EUROPEAN QUALITY (FEQ) This grade refers specifically to teak, generally equal to or even better than FAS grade and the highest grade available; free from sapwood, bee holes and loose knots.
- FIRST EXPORT QUALITY (FEQ) This grade is typically a South American grade and a First European Quality equivalent for woods such as ipé and cumaru, and is the highest quality available.
- FIRSTS AND SECONDS (FAS) Generally the highest NHLA grade available and it must be 83%-100% clear-wood cuttings. Clearness is measured in large rectangular areas called cuttings and it is graded on the best face, however both faces of the board must meet the minimum requirement for FAS. Provides user with long, clear cuts and is best used for high quality furniture, interior joinery and solid wood mouldings.
- FAS ONE FACE (F1F) The better face must meet all FAS requirements, while the poor face must meet the requirements of Number 1 Common grade, thus ensuring the buyer of at least one FAS face.
- SELECT GRADE NHLA grade that has FAS quality on the good side and No. 1 Common quality on the poor side. It is virtually the same grade as F1F except for the minimum board size required, typically too short and narrow to be F1F for FAS. Selects are associated with the northern regions of the USA and are frequently shipped with FAS grade lumber.
- NUMBER 1 COMMON (NO. 1C) NHLA grade which must be 67% clear on both faces of the board. It is often referred to as Cabinet grade because of its adaptability to the standard sizes of kitchen cabinet doors in the USA. There are little to no natural defects such as worm holes or reverse fiber on either face. There are little to no machine defects such as planer chatter or hit and miss. Some pin knots are allowed with no dead knots.
- NUMBER 2A COMMON (NO. 2AC) NHLA grade which must be 50% clear on the poorest face of the board. It is often referred to as Economy grade because of its price and suitability for a wide range of furniture parts. It is also the grade of choice for the US hardwood flooring industry. Expect natural defects such as worm holes, reverse fiber, and more pin knots with no dead knots. Machine defects are often limited to one face.
- PRIME GRADE This grade is used by the import market to denote the highest grade available reclaimed woods. One face and one edge of boards within specification will be free from defects but are permitted features of: live knots of any size and unlimited color variation, wide and long boards may also have splits up to 2mm wide with a maximum length of 10% of the board, and/or 1 to 3 plugged nail holes up to 25mm diameter.
GREEN Freshly sawn lumber, or lumber that has received no drying; unseasoned.
GREEN CERTIFICATION Landowners who actively manage their woods can apply for green certification. Several agencies perform reviews and issue certification for the Forest Stewardship Council (FSC), including: the non-profit Smartwood, the for-profit SCS (Scientific Certification Systems) and BM TRADA. These agencies charge to ensure that land is properly and sustainably managed and that loggers employ best management practices (BMP) to cut wood on certified woodlots. To maintain its green certification status from landowner to consumer, lumber mills must also be certified in chain of custody arrangements, that is, they ensure that certified logs are stored and milled separately from non-certified logs.
HECTARE A measure of area equaling 2.471 acres.
HIDDEN FASTENER SYSTEM A pre-fabricated piece of hardware used to connect deck planks so that the face of the wood is not disturbed with screws or nails for a clean aesthetic. The fastener is typically placed in the groove on the edge of the plank, then screwed into the joist to hold the board in place and to automatically space it from the next board.
HARDWOOD Any close-grained wood from deciduous trees. Generally one of the botanical groups of trees that have broad leaves in contrast to the conifers or softwoods. The term has no reference to the actual hardness of the wood.
HEARTWOOD The wood extending from the pith to the sapwood, the cells of which no longer participate in the life processes of the tree. Heartwood is generally darker than sapwood, but the two are not always clearly differentiated.
JANKA HARDNESS A scale that measures of the relative hardness of wood. The test measures the force required to push a steel ball with a diameter of 11.28 millimeters (0.444″) into the wood to a depth of half the ball’s diameter (the diameter was chosen to produce a circle with an area of 100 square millimeters). In the United States, the measurement is in pounds-force. It is one of the best measures of the ability of a wood species to withstand denting and wear. It is also a good indicator of how hard a species is to saw or nail.
KILN DRIED (KD) Lumber that has been dried in a kiln with the use of artificial heat; seasoned. Freshly cut green lumber may be sold green, air dried, or dried in a kiln to accelerate removal of the moisture in the wood. Drying wood in a kiln is an art to ensure that the wood dries evenly to retain its strength and aesthetic properties. Different species dry at different rates. Kiln dried lumber commands a higher price than green or air dried lumber.
LINEAR FOOT (LN. FT. OR LF) System of measuring length.
L.T.L. (LESS THAN LOAD) An LTL shipment is when there is less than a truck load of product to be shipped at one time.
LUMBER Solid wood that has been sawn to a particular size. The product of the saw and planing mill not further manufactured than by sawing, resawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching.
- BOARDS Lumber that is nominally less than 2″ thick and 2″ or more wide. Boards less than 6″ wide are sometimes called strips.
- EASED LUMBER Part of the edge detail where the corner of the board is rounded with a radius cut, typically performed on boards to be used as exterior decking.
- MATCHED LUMBER Lumber that is edge dressed and shaped to make a close tongue-andgrooved joint at the edges or end when laid edge to edge or end to end.
- NET (DRESSED) SIZE The dimensions of lumber after being surfaced with a planing machine. The net size is usually 1/2″ to 3/4″ less than the nominal or rough size. A 2″ x 4″ stud, for example, actually measures about 1-1/2″ x 3-1/2″.
- NOMINAL SIZE As applied to timber or 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 dressed (surfaced) but which has been sawn, edged, and trimmed.
- SHIPLAPPED LUMBER Lumber that is edge dressed to make a lapped joint.
- SURFACED LUMBER Lumber that is dressed by running it through a planer. Lumber that is Surfaced Four Sides (S4S) means that all four faces of the board have been dressed. Boards can also be Surfaced One Side (S1S) or Surfaced Two Sides (S2S).
- TIMBERS Lumber that is nominally 5″ or more in the least dimensions. Timbers may be used as beams, stringers, posts, caps, sills, girders, etc.
MICRO-BEVEL A finished edge that refers to a very slight round or angular cut edge of a flooring plank. Micro-bevel edges give definition to the flooring plank and help reduce uneven plank height. The micro-bevel is meant to help hide minor irregularities.
MILLWORK Building materials made of finished wood that have been specially manufactured by a plant or mill. Millwork includes moulding and trim, doors and windows and their frames, staircases, cabinets and other specialty items.
MINERAL STREAK An olive to greenish-black or brown discoloration.
MOISTURE CONTENT (M.C.) The weight of water contained in wood expressed as a percentage of the weight of the oven dry wood. Most hardwoods in the United States are produced to standards developed by the National Hardwood Lumber Association (NHLA). No single moisture content, however, is specified for hardwoods because the uses are more specialized. The moisture content must be specified by the buyer and agreed to by the seller; a 10-12% moisture content specification is common.
MOULDING A trim piece of millwork used either strictly for decoration or for both decoration and to finish a joint.
NET TALLY Otherwise known as a dried tally. The board footage of lumber figured when the board is seasoned.
OLD GROWTH A forest of mature or over mature timber that is beyond its peak growing period.
PIN KNOT A knot which does not exceed 1/8″ in average diameter.
PITH The small soft core occurring in the structural center of the log.
PLAIN-SAWN Plain-sawn hardwood boards are produced by cutting tangentially to a tree’s growth rings, creating the familiar “flame-shaped” or “cathedral” pattern. This method also produces the most lumber from each log, making plain-sawn lumber a cost effective design choice.
PLYWOOD Sheets of wood consisting of three or more sheets of wood glued and bonded by heat and pressure with the grain of each sheet running perpendicular to adjacent layers.
POCKET An excessive local accumulation of resin or gum in the wood.
PRE-GROOVED A milling process, typically used in exterior decking, where both edges of the board contain a slot (groove) designed to receive a hidden fastener system.
PROFILE The shape of the wood, as seen from a side view.
QUARTER-SAWN Quarter-sawing means cutting a log radially (90-degree angle) to the growth rings to produce a “vertical” and uniform pattern grain. This method yields fewer and narrower boards per log than plain sawing, boosting their cost significantly. Quarter-sawn boards are popular for decorative applications.
REFORESTATION The natural or artificial restocking of an area with forest trees.
RESAWING The process of sawing lumber in two lengthwise, parallel to the wide face. It is usually, though not always, done through the middle of the board, producing two equal sized boards, each approximately half the thickness of the original. Resawing changes the thickness of the lumber but not its width.
RIPPING The process of sawing lumber in two lengthwise perpendicular to the wide face. Ripping changes the width of the lumber but not its thickness.
SAPWOOD The living wood of pale color near the outside of the log.
SEASONING Removing moisture from green wood to improve its serviceability.
SHRINKAGE The contraction of wood fibers caused by drying below the fiber saturation point (usually around 25-27% M.C.). Values are expressed as a percentage of the dimension of the wood when green.
SOFTWOOD Any soft, light-textured wood of a coniferous tree.
SPECIES A commercial name assigned to tree.
SPECIFIC GRAVITY As applied to wood, the ratio of the ovendry weight of a sample to the weight of a volume of water equal to the volume of the sample at a specified moisture content (green, air-dry, or ovendry). This term applies to the wood’s ability to float or sink in water.
SPLIT A lengthwise separation of the wood, due to the tearing apart of wood cells.
SUSTAINED HARVEST A level of harvest that does not exceed annual growth, so that at least as much is available for harvest in 50 years as today.
TONGUE-AND-GROOVE (T&G) A method of fitting similar pieces of wood together, edge to edge, used mainly with flooring and paneling. Each piece has a slot (the groove) cut all along one edge, and a thin, deep ridge (the tongue) on the opposite edge. The tongue projects a little less than the groove is deep. The tongue is inserted into the groove and thus two pieces fit together closely.
VENEER Thin sheets of wood of a specified thickness that are peeled, sliced, or sawn from logs for use in plywood, paneling and furniture.
WARP Warp is any variation from a true or plane surface. Warp includes bow, crook, cup and twist, or any combination thereof.
WEATHERING The mechanical or chemical disintegration and discoloration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds, and the alternate shrinking and swelling of the surface fibers with the continual variation in moisture content brought by changes in the weather. Weathering does not include decay.
WOOD FLOORING Most wood flooring is made of hardwoods, such as oak, maple and pecan, as well as many other exotic imported species. Wood flooring can come in many sizes and varieties, including pre-finished or unfinished.
- DISTRESSED WOOD FLOORING A heavy artificial texture in which the floor has been scraped, scratched, or gouged to give it a worn antique look.
- END MATCHED A common milling procedure whereby the ends of individual pieces of flooring have a tongue milled on one end and a groove milled on the opposite end. When the individual strips or planks are butted together, the tongue of one piece engages the groove of the next piece.
- ENGINEERED WOOD FLOORING This type of flooring should not be confused with laminate wood flooring. Engineered flooring is produced by adhering layers of plastic laminate veneer with real wood. The main difference between this type of wood and laminate flooring is that laminate flooring contains no actual wood.
- HAND HEWN FLOORING This flooring offers an Old World, lived-in appearance, which is created by a simple draw-knife craftsman technique that puts waves into the face of the board. As a result, the solid floor face gives a unique impression of age and character. Hewing is an old method of cutting wood, whereby the craftsman turns the log on its side, and chips off pieces of wood until the wood is down to the marked line.
- LAMINATE WOOD FLOORING An assembly made by bonding layers of veneer or lumber with an adhesive.
- PARQUET FLOORING A “tile” composed of individual slats held in place by a mechanical fastening or other means such as paper backing. A square may or may not possess tongues and grooves to interlock, and is not necessarily regular in dimension.
- PLANK FLOORING Unlike strip flooring, the widths of plank flooring can vary. Typical thicknesses are 1/2″ or 3/4″ and a range in widths from 3″ to 8″.
- SOLID WOOD FLOORING Typically tongue and groove flooring that is milled from one thick piece of wood that can be sanded and refinished numerous times.
- STRIP FLOORING This type of flooring is denoted by the thickness and width of the wood planks. Strip flooring normally has a set width, and typically ranges in thickness from 5/16″ to 3/4″ thick. Being the most popular wood flooring, it is made of long, narrow (usually around 3″ wide), tongue-and-groove boards that are normally end-matched.
- UNFINISHED Flooring that must be sanded and finished after installation.
YIELD The proportion of the log converted into lumber.