Hardwood Flooring Terminology used by hardwood and laminate manufacturers, flooring distributors, floor retailers, wood and laminate flooring installers, flooring inspectors and others in the hardwood and laminate floor covering and construction industry.
Hardwood Flooring Terminology and Laminate Terms
Acclimation: Adaptation of the laminate floor to its installation environment.
Acoustical Properties: Absorbance, reflection or transmission of sound waves.
Acrylic/Wood: The generic name for wood-plastic-composites that utilize wood impregnated with acrylic monomers and polymerized within the wood cells through gamma irradiation. Heat radiation is used to cure some versions. (A semi-built-in finish is developed in acrylic/wood parquet.)
Adhesion: A chemical process by which two materials can be joined together.
Air-Dried: Drying by exposing to air without the use of artificial heat and within a yard or shed.
Annual Growth Ring: The seasonal layer of growth including the spring and summerwood formation that develops during a single growing season.
Antistatic: Ability to limit the accumulation of static electricity on a surface.
Backer: In laminated flooring the bottom layer is called backer layer or balancing layer and is usually made from a resin-impregnated Kraft paper. The backer is designed to be the same weight as the wearlayer to provide balance and stability. If the backer is lighter or heavier than the wearlayer, the boards will cup or bow after installation and cannot be repaired.
Balanced Construction: A panel construction that has materials of similar properties bonded to both sides of the panel.
Base Shoe: Similar to quarter round in profile, it is a molding designed for attaching to a base molding to cover the expansion space.
Bastard Sawn: Lumber (primarily hardwoods) in which the annual rings are at an angle of 30 to 60 degrees of the lumber surface.
Beveled Edge: (See eased edge)
Blocks: (See Parquet Floor Squares)
Board-foot: A unit of measurement that is represented by a board 1 foot long, 1 foot wide, and 1 inch thick or its cubic equivalent. In practice, the bard foot calculation for lumber 1 inch or more in thickness is based on the nominal thickness in width and the actual thickness in length. Nominal thickness of lumbers less than 1 inch is calculated as 1 inch.
Bow: In lumber the distortion in which there is a deviation, in a direction perpendicular to the flat face as measured from a straight line from end to end.
Burl: A swirl or twist of the grain of the wood that does not contain a knot but usually occurs near a knot.
Chatter Marks: Slight indentations that cause a ripple effect on the surface of the wood floor. They are usually caused by a sanding machine that has an out-of balance drum, bad drive belts or a foreign object stuck on the wheels. Chatter marks are most noticeable on gloss finishes in areas with direct or side lighting and at eye level.
Chemical Resistance: The degree to which a material resists visual or physical degradation from exposure to various household and/or industrial chemicals.
Chipboard: Paperboard formulated for a variety of purposes and under a variety of specifications including two of the more common that may or may not be included are strength and color. It is usually fabricated from paper stock with a relatively low density in the thickness of 0.006 inch and up.
Chipped Grain: An area in which pieces of wood have been pulled or chipped away from the surface during machining. Also referred to as torn grain.
Colorfastness: The ability of a material to retain its original color upon exposure to light or other source of degradation (i.e., light resistance).
Compression Set: Occurs when wood strips or parquet slats absorb excess moisture and expands excessively crushing the cells along the edges of adjoining pieces in the floor. This results in a loss of resiliency and creates cracks when the floor regains its moisture content.
Compact Laminate: High Pressure Laminate greater than or equal to 2 mm (0.08 in) in thickness.
Coniferous: (See softwoods)
Continuous Press Laminate (CPL): A manufacturing process where the laminate is formed on a continuous double-belted press.
Continuous Laminate Flooring: A product created by permanently bonding a continuous press laminate to a core.
Core: In laminated flooring, the core provides for strength and impact resistance and can be made from high or medium-density fiberboard, particle (chipboard, or polyurethane foam. Particleboard and fiberboard are produced from compressed wood fibers mixed with bonding agents and is vulnerable to moisture.
Crook: The distortion that occurs within a board that has a deviation in a direction perpendicular to the edge, from a straight line from end to end of the piece.
Crosspull: A condition that occurs at an end-joint with the ends of flooring strips pulled in opposite directions.
Crowning A “convex” or “crowned” condition or appearance where the center of individual strips becomes higher than the edges. (Opposite of cupping.)
Cupping: A “concave” or “dished” condition or appearance where the center of individual strips becomes lower than the edges. (Opposite of crowning.)
Cure: The change of adhesives properties by chemical reaction (which may be condensation, polymerization, or vulcanization) resulting in the development of maximum strength. Commonly accomplished by the action of heat or a catalyst, with or without pressure.
Custom Floors: Wood floor that is specifically made to order. Offers flexibility for design, grade, specie, etc.
Decay: Decomposition or wood by fungi.
Advanced Decay: The older stage of decay is easily recognized by the woods soft, crumbly or pitted areas. Decided discoloration or bleaching of the rotted wood is frequently apparent.
Incipient Decay: The early decay stage that has not proceeded far enough to soften or otherwise perceptibly impair the woods hardness. It is routinely accompanied by a slight discoloration or bleaching of the wood.
Deciduous: (See hardwoods)
Décor Layer: The layer of laminate flooring providing visual aesthetic properties.
Deflection: The bending of a material between supports when a load is applied.
Delamination: The separation of layers in a laminate, through failure within the adhesive or at the bond between the adhesive and laminate.
Density: Unit weight per volume of a panel expressed in lb/ft3 or kg/m3.
Depression: A dent in the surface of a panel.
Diffuse – Porous woods: Certain hardwoods E.I., hard maple, in which the pores tend to be uniform in size and distribution throughout each annual ring or to decrease in size slightly and gradually toward the outer border of the annual growth ring.
Dimensional Stability: The ability to maintain the original planned dimensions when influenced by a foreign substance. Wood is hydroscopic, and is not dimensional stable with changes in moisture content below the fiber saturation point.
Direct Laminate Flooring: A product where resin impregnated material layer(s) is permanently bonded to the core.
Direct Press Laminate (DPL): A laminating process by where the wear layer and décor surface are bonded directly to the substrate in a single step.
Distressed: Creation of an antique or timeworn appearance by creating an artificial texture of a floor by techniques such as scraping, scratching and gouging.
Dry Wall: Interior covering material, such as hardboard, plywood or gypsum board that is applied in large sheets or panels.
Eased edge: A chamfered or beveled edge of strip flooring, plank, block and parquet at approximately a 45 degree angle.
End Joint: The joint created where two pieces of flooring are joined end to end.
End Matched: Plank or strip flooring milled using a tongue and groove method of joining.
Embossing: A process by which the surface of the panel is given a texture.
Equilibrium Moisture Content: The moisture content at which a wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.
Expansion: In hardwood expansion is swelling resulting from long-term dampness. Oak flooring expands and contracts across the grain with changes in moisture conditions.
Expansion Cork: A cork product that is used to fill the expansion space in a hardwood floor installation.
Expansion Gap: A space necessary between fixed objects (i.e. walls of a room, pipes, and cabinets) and between the material itself to allow for the movement of the material.
Feature Strip: A molding accessory that is used to separate parquet squares into patterns that are larger than the individual parquet units. Available in various lengths and in widths of 5/16” to 2” and the same thickness as the parquet. May be tongue and grooved to match the adjacent plank or parquet.
Fiberboard: A widely used generic term that is inclusive of sheet materials of widely varying densities manufactured of refined or partially refined wood or vegetable fibers. A variety of materials and bonding agents are added to increase strength, resistance to moisture, fire or decay and to improve other qualities.
Fiber Saturation Point: The stage in drying or wetting wood at which the cell walls are saturated with water and the cell cavities are void of water. It is usually taken as approximately 30% moisture content, based on oven-dry weight.
Figure: The inherent markings, designs or configurations on a woods surface and produced by the annual growth rings, rays, knots and deviations from the regular grain.
Filler: 1. In woodworking, any substance that is used to fill the holes and irregularities in planed or sanded surfaces to decrease the porosity of the surface before applying a finish coat. 2. A wood putty, plastic wood or other material that is used to fill cracks, knot holes, worm holes, etc.
Fire Resistance: A materials ability to withstand fire or give protection from it.
Fire Retardant: A chemical or preparation of chemicals that is used to retard the spread of fire over the surface or to reduce flammability.
Fishtail: Swelling at the ends of boards from moisture of a shot term nature.
Flag: A heavy dark mineral streak that is shaped like a banner.
Flag Wormhole: One or more wormholes that are surrounded by a mineral streak.
Flakeboard: A particle panel that is composed of flakes.
Flame Spread: The development of a flame away from its source of ignition such as across the surface of a liquid or a solid, or through the volume of a gaseous mixture.
Flecks: The broad irregular-distinct-figure in quarter-sawn oak flooring.
Floating Floor: Installation method by which the flooring panels are connected together and not attached to the subfloor.
Fuzzy Grain: Roughening of the woods surface, resulting from absorption of moisture sufficient to expand the wood cells at the immediate surface. The result is a fuzzy feel when touched.
Grain: A general term that describes the direction and alignment of the wood elements.
Growth Rings: Increments of growth, which appear as figures in the floor. Seen in a cross section of a log as rings around the center of the log. When only one growth ring is formed during a year, it is called an annual ring. Viewing the end of a parquet slat, they appear in bands of layers.
Hardwood: Commonly one of the botanical groups of deciduous trees that have broad leaves in contrast to the conifers or softwoods. This term does not refer to the actual hardness of the wood.
Heartwood: The wood extending from the pith of the sapwood, the cells of which no longer participate in the life processes of the tree. Heartwood is usually darker than sapwood.
Heavy Streaks: Spots and streaks that are large enough to significantly affect the appearance of a wood.
High Density Fiberboard (HDF): A fiberboard with density greater than 800 kg/m3 (50 lb/ft3).
High Pressure Laminate (HPL): A laminating process where materials are consolidated under heat and pressure exceeding 5.17 MPa (750 psi).
High-Pressure Laminate Flooring: A product created by permanently bonding high-pressure decorative laminate to a core.
Honey Combing: Checks that may not be visible at the surface but commonly occur in the interior of a piece of wood and usually along the rays.
Hydroscopic: The ability of a substance to absorb and retain moisture or lose or throw off moisture. Wood as a hydroscopic material expands with the absorption of water and shrinks with the loss of moisture.
Impact Resistance: Ability to resist fracture or damage from a falling object.
Inlay: A decorative effect used in flooring by combining elements of the same material but with different colors or patterns (e.g., borders or feature strips).
Intumesce: Used in reference to certain fire retardant coatings to describe the providing of a low-density film through expansion with heat.
Irradiated Hardwood: A process wherein a hardwood floor is bonded at the molecular level with acrylic through the use of gamma radiation.
Jointed Flooring: Strip flooring that is manufactured with square edges and no tongue and groove and is usually end matched. Primarily used for areas subject to routine damage and easy replacement is desirable. Common strip flooring is in birch, beech maple, hard maple or pecan.
Joist: Parallel beam used in series to support floor or ceiling loads and supported in turn by larger beams, girders, or bearing walls.
Kiln (Pronounced “Kill”) A chamber that has air flow, temperature and relative humidity control for drying lumber, veneer and other wood products.
Kiln Dried: Dried in a kiln.
Knot: The portion of a branch or limb, which has been surrounded by succeeding growth of a stem. ‘Me shape of the knot as to its visibility on a cut surface depends on the angle of the cut relative to the long axis of the knot.
Small Knot: In hardwood strip flooring not over ½” in diameter.
Pin Knot: Not over ½” in diameter.
Sound Knot: A knot that is cut approximately parallel to its long axis exposing an elongated section.
Laminate: A product made by bonding together two or more layers of material.
Laminated Plank Flooring: A floor product usually produced from wood pulp, paper and plastic. This assembly routinely consists of three basic components: core, wearlayer and backer.
Laminated Wood: An assembly that is made by bonding layers of materials with an adhesive. 2. Sometimes referred to edge-glued lumber items such as treads, etc.
Manufacturing Defects: Defects or blemishes that develop during manufacturing such as chipped grain, tom grain, skips in dressing, hit and miss (a series of surfaced areas with skips between them), machining variations, burns and mismatching.
Medium Density Fiberboard (MDF): A type of core material primarily composed of lignocellulosic fibers combined with a synthetic resin or other suitable bonding system and bonded together under heat and pressure.
Medullary Rays: Rays of cells extending from the pith of the bark with the primary function of storing food and transporting it horizontally within the tree. These strips of cells extend in radial pattern within the tree. The rays vary in height from a few cells up to four or more inches in an oak. On quarter-sawn oak the rays form a conspicuous figure that is sometimes referred to as flecks.
Melamine Resin: A thermosetting resin used in the impregnation process of materials used to make laminate flooring.
Mineral Streaks: The accumulation of mineral matter that is introduced by sap flow and causes an unnatural color within the wood that ranges from greenish brown to black.
Mixed Media: A predominantly wood floor that incorporates the use of other materials such as stone, ceramic, metal or painted finishes.
Moisture Content: The amount of moisture expressed as a percentage of the weight of the oven dry wood.
Moisture Meter: A tool used to measure moisture content.
Mosaic Parquet: A parquet flooring arranged in designs using small pieces to form a double herringbone, bordered or other design.
NOFMA hardwood flooring is manufactured at 6% to 9% moisture content with a 5% allowance for pieces containing up to12% moisture content. APA parquet flooring is to have 7% to 11% moisture content at the time of shipment with an allowance of 5% of the material outside of that range.
Nosing: A trim used to cover the outside corner of a step.
Nominal Size: In lumber it is the size by which the material is known or sold but may actually differ from the actual size.
Oriented Strand Board: A particle panel composed of strand-type flakes with purposefully aligned directions which make a panel stronger, stiffer, and with improved dimensional properties in the alignment directions than a panel composed of random flake orientation.
Overlay: A product of paper, plastic, film, metal foil, or other material incorporated into the laminate flooring surface that provides the wear resistance and protection.
Panels: Finished sections of the laminate flooring (e.g. planks, tiles, and squares).
Parquet: A patterned floor.
Parquet Floor Square: Individual wood slats that are joined together to form a tile-like square.
Parquet Floor Units: A joined unit that consists of 3 to 4 tile squares.
Particleboard: A generic term for a material manufactured from wood particles or other cellulosic material and a binder.
Pattern End Matched: When the ends of the flooring panels, typically similar patterns, are matched end to end to yield a continuous linear effect.
Peaking: Areas of the laminate flooring at adjoining panel seams that have risen above the intended horizontal plane of the flooring surface.
Pin Worm Hole: In hardwood flooring it is a small round hole that is made by a small wood boring insect and not over 1/16” in diameter. Also called Pinholes.
Pith: The small, soft core that occurs near the center of a tree trunk, branch, twig or log.
Plainsawn Wood: Wood that is sawed from a hardwood log so that the annual growth rings make an angle of less than 45 degrees with the surface of the piece. The angle exposes the pores of the springwood and dense summerwood of the annual growth ring in ring porous woods to produce a pleasing grain pattern.
Planer Bite: A groove that is cut in the surface of the wood piece deeper than intended by the planer knives.
Plank: Solid boards that are usually thicker than ¾” and 3” to 8” wide.
Plugs: Dowels that simulate the Colonial American plugged or pegged plank appearance.
Prefinished: A floor that is finished during the manufacturing process and requires installation only.
Pressing: A manufacturing process by which material layers are consolidated using pressure.
Quartersawn Wood: Wood that is sawed from a hardwood log so that the annual growth rings make an angle of 45 to 90 degrees with the surface of each piece.
Raised Grain: A roughened or fuzzy condition on the flooring surface in which the dense summerwood is raised above the softer springwood but is not torn or separated.
Ray: Strip of cells that extend radial within a tree and vary in height from a few cells to 4 or more inches in oak. The primary purpose of the rays is to store food and transport it horizontally within the tree. On quarter-sawn oak flooring the rays form a conspicuous figure that is sometimes referred to as flecks.
Ray Fleck: A portion of a ray appearing distinctly on the face of a quartersawn slat.
Reducer Strip: A molding strip teardrop in shape that is used to reduce a floor elevation where it meets a lower surfaces such as at doorways or around fireplaces.
Relative Humidity: A ration of the amount of water vapor that is present in the air to that which the air would hold at saturation at the same temperature. While usually considered on the basis of the weight of the vapor, for accuracy it should be considered on the basis of vapor pressures.
Residual Indentation: The difference between the initial thickness and the final thickness after performing the static load test.
Resins: A polymeric material used for impregnating and bonding layers of laminate flooring.
Rift Sawn: Lumber (primarily hardwoods) in which the annual rings make angles of 30 to 60 degrees with the surface of the piece. (Also referred to as Bastard Sawn)
Ring Porous: A group of hardwoods in which the pores are comparatively large at the beginning of each annual growth ring and more or less abruptly decrease in size toward the outer portion of the annual growth ring. The smaller pores are summerwood and the larger pore springwood.
Sapwood: Usually lighter in color than heartwood it is the wood near the outside of the tree.
Sawn: (See bastard-sawn, plain-sawed and quarter-sawn.)
Screeds: Lumber (usually 2” x 4”) that is attached to a concrete subfloor to provide a nailing surface for tongue and groove strip flooring or a wood subfloor.
Seams: A line or junction where panels are connected together.
Sleeper: Another name for screeds.
Shake: A separation found along the grain, with the greater part occurring between the annual growth rings.
Sheathing: Structural covering that is usually plywood or other boards that are placed over the exterior studding or rafters.
Shrinkage Cracks: In hardwood cracks between boards that have developed from expansion due to excess moisture gain and loss of the moisture as it dries. Referred to as shrinkage.
Slats: Small solid hardwood pieces, which form mosaic, parquet squares.
Slip-Tongue: A spline or small strip of wood or metal that is used to reverse or change direction in installing standard tongue and groove strip flooring. Sometimes used in laying 3/4” solid tongue and groove parquet.
Softwood: General term that describes lumber produced from conifers. (Needle and cone bearing trees.)
Split: Separations of wood fiber that run parallel to the grain.
Squares: usually produced with an equal number of slats.
Square Edge: A wood flooring that is not tongue and groove.
Square Joint: Tongue and groove strips or plank flooring with edges that are neither eased nor beveled.
Stain: A discoloration that develops in or on a floor and is other than the natural color.
Stain Resistance: The degree which a material resists permanent discoloration from exposure to household items and/or industrial chemicals.
Streaks: (See mineral streaks)
Strip Flooring: Solid boards that are manufactured to be installed in parallel rows.
Stud: Structural unit used as supporting element in walls and partitions.
Substrate: The core material of the laminate flooring.
Sub-floor: A pre-existing supporting surface in a structure.
Surface-Finish: A finish material, which penetrates the pores of the wood, providing a finish that is in the wood rather than on the surface.
Surface Layer: The outermost layer of laminate flooring designed to be the visible side when installed (i.e., wear layer).
Thermofusing: A process where resins are consolidated under heat and pressure to create a permanent bond.
Thermosetting Resins: Resins that cure by chemical reaction to form bonds and do not melt when exposed to heat.
The Weinheimer Group: A Nationally recognized flooring inspection company and compiler of this glossary.
Tile: A panel of geometric shapes (e.g., squares, rectangles, etc).
Tongue & Groove (T & G): A tongue (male appendage) is milled on one side and a groove (female appendage) is milled on the other side. As the floor is installed the tongue and groove are united.
Trim: The finish materials such as molding and baseboard.
Underlayment: A material used between the laminate flooring and the subfloor (e.g., foam padding).
Unfinished: A wood product that requires sanding and a finish application after installation.
Units: Four or more basic mosaic parquet squares or four or more slats in ¾” parquet and usually made with a combination of tongue and groove strip flooring and parquet.
V-Joint: A plank flooring term that indicates that the edges are eased or beveled to simulate cracks in floors of early Colonial American homes.
Vapor Barrier: A material with a high resistance to vapor movement that is used to control condensation or prevent migration of moisture.
Waferboard: A particle panel product that is made of wafer-type flakes. It is usually produced to provide equal properties in all directions parallel to the plane of the panel.
Warp: Crowning, cupping, or crook.
Warping: Any distortion to a piece of flooring from its true plane that may occur in seasoning.
Wearlayer (Wear Layer): In laminated flooring the wearlayer usually consist of multiple layers of Kraft paper that has been impregnated with phenolic resins and pressed together under high heat and pressure. This is the HPL (high-pressure lamination) process, the first step of the CPL (continuous pressure lamination) process, the second being the attachment of the wearlayer and backer layer to the core. The bottom layer of Kraft paper is imprinted with a photograph that provides the floors pattern or design.
Wear Resistance: Ability of the laminate flooring surface to resist wear through its décor layer.
Wire Brushing: A method of producing a distressed texture to a hardwood floor.
Wood and laminate glossary of terms compiled by The Weinheimer Group LLC, NWFA – National Wood Flooring Association Certified Flooring Inspectors.