Glossary
A Glossary of Terms Related to Hardwood Floor
Here are some of the most important terms you are likely to encounter on many manufacturer Websites.
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Acclimation: Letting flooring adjust to the environment in which it will be installed. This is crucial to prevent excessive expansion or contraction due to humidity in the air or other job conditions.
Accent Strip: A strip of wood flooring used in contrasting color to the rest of flooring. Can be used around the edges of a room, around a fireplace, or other features in order to highlight a specific area.
Belt Sander: Almost the same machine as a drum sander. Differences are that instead of being directly driven by a belt and pulley with a slotted drum, it is driven by an overhead spindle and has no slotted drum. However, some machines have both. The main advantage of a belt sander is that it uses belts – continuous loops of sand paper – thus in theory leaving fewer chatter marks.
Bird’s Eye: A character found in maples. Very appealing, but relatively rare and expensive.
Border: A decorative inlay of different colored woods assembled in a pattern around the perimeter of a room or rooms. Flooring is used to fill in and around the border, commonly called the “field.”
Buffer: A walk-beside sanding machine used for fine sanding, commonly called “screening.”
Bull Nosing: A plank of wood with a curved edge. Normally used at the tops of stairs or edges of an upstairs catwalk. Makes a nice finished edge for flooring.
Butt Joint: Where the ends of boards meet together in a wood floor.
Classic: 3/4″ thick solid prefinished hardwood flooring. Classic flooring is designed to be nailed or stapled down over a wood subfloor.
Checks: Longitudinal separation of the fibers in wood that do not go through the whole cross section. Checks result from tension stresses during the drying process.
Compressive strength parallel to grain: Maximum stress sustained by a compression parallel-to-grain specimen having a ratio of length to least dimension of less than 11.
Compressive stress perpendicular to grain: Reported as stress at proportional limit. There is no clearly defined ultimate stress for this property.
Coloring: It is important to distinguish between wood’s natural coloring and variations caused by external factors. Each species has its own grain, and thus its own typical coloring. In the same block of wood, color varies according to the density of the fibers. This is what creates wood’s unique pattern. Various natural factors can alter wood’s coloring, such as exposure to light, air, and humidity. The color can be changed with stains and varnishes. The effect will vary in intensity depending on the density of the fibers and the degree to which they absorb the stains and varnish.
Commercial: We distinguish between floors installed for commercial and residential use, especially for the warranty. A location is considered commercial if it is open to the public or is a place of work. A residential location is one where people live. In commercial locations, floors are subjected to heavier traffic.
Compressive Strength Parallel to Grain: Maximum stress sustained by a compression parallel-to-grain specimen having a ratio of length to least dimension of less than 11.
Compressive Stress Perpendicular to Grain: Reported as stress at proportional limit. There is no clearly defined ultimate stress for this property.
Cupping: The uplifting of the edges of flooring due to excessive moisture.
Curling: The end result of what happens to flooring when it was sanded when the moisture was still too high in the wood. When the flooring dries out, the edges curl downward, causing crowning in the center of the boards.
Decor Layer: The top finish layer of a laminate floating floor, adhered to an HDF core. The decor surface is a photographic reproduction of a real-wood surface or ceramic tile. The decor layer is covered with a top layer made of aluminum oxide.
Density: Weight per unit volume. Density of wood is influenced by rate of growth, percentage of late wood and in individual pieces, the proportion of the heartwood.
Digs: A term used by floor refinishers for edger gouges.
Dimensional Stability: A term that describes whether a section of wood will resist changes in volume with variation in moisture content (other term: movement in performance).
Door Jamb Saw: A specialty tool for undercutting door jambs, cabinets, etc. Makes for a professional look.
Dry Sawn: A method of precision sawing hardwood to the desired strip thickness without having to presoften the wood by soaking.
Drum Sander: A walk-behind sander used for sanding large areas. Many run on 220V power. Uses cut sheets of sandpaper on a cylindrical, slotted drum.
Edger: Small but powerful disk sander used for sanding areas that a drum sander can’t reach. Difficult to master.
Engineered: 3/8″ thick prefinished hardwood flooring composed of a hardwood layer glued on 5 ply plywood. Some manufacturers Engineered flooring is specially designed to be installed over concrete, but can also be nailed or stapled down over a wood subfloor.
Engineered Floating Floor: A hard-surface floor made from wood or other natural products adhered to a core such as High-Density Fibreboard (HDF) for structural stability and durability. An engineered floating floor is designed for minimal expansion and contraction with changes in interior temperature and humidity.
Expansion Gap: A gap (usually 3/8″) that must be left around the edges of a room and any installed obstructions to allow for natural expansion and contraction in a floating floor that occurs with changes in room temperature and humidity.
Exotic: Wood imported from countries with climates different from that in North America are considered exotic. For example, Santos Mahogany (Cabreuva), Brazilian Cherry (Jatoba) and Sapele are exotic species, whereas Maple and Oak are indigenous.
Flooring Nails: Sometimes referred to as “cleats,” these are special nails used in a flooring nailer. They are either “L” or “T” shaped.
Floating Reducer: A sloping, graduated moulding constructed of wood or polymer, used to join floating floor planks or tiles to an adjoining floor surface of unequal height.
Floating Stair Nose: A moulding constructed of wood or polymer, used along the leading edge of a stair tread to finish off the installation of floating floor planks or tiles over existing stair treads.
Figure: The pattern produced in a wood surface by annual growth rings, rays, knots, deviations from regular grain, such as interlocked and wavy, and irregular coloration.
Gloss: The luster or shine of a surface when light is reflected off it. A glossy surface reflects more light than a matte surface.
Glueless Floating Floor: Any engineered floor that fastens in place without nails or glue over an existing floor or subfloor.
Grade: Wood strips are categorized according to variations in their natural coloring. “Grade” refers to visual aspect only and has absolutely no bearing on quality.
Grain: The direction, size, arrangement, appearance, or quality of the fibers in sawn wood. Straight grain is used to describe lumber where the fibers and other longitudinal elements run parallel to the axis of the piece. The pattern created by the variations in the density of wood fiber particles as a tree grows. Fiber densities vary from one species to another.
Grain Raise: The lifting of wood surface fibers due to moisture in the application of finish.
Groove: In wood strips with a tongue and groove joint, a tongue is milled on one edge of the strip and a groove is cut into the opposite edge. The form of the joint is also referred to as male (tongue) or female (groove). When the flooring is installed, the tongue of each strip is inserted into the groove of the adjacent strip.
Gum Pocket: An excessive local accumulation of resin or gum in the wood.
Hardness: The wood’s resistance to impact. Hardness depends on the density of the fibers and is measured in terms of the pressure required for a steel ball to mark the wood to a certain depth. The harder the wood, the higher the pressure required. Generally defined as resistance to indentation using a modified Janka hardness test, measured by the load required to embed a 11.28 mm (0.444 in.) ball to one-half its diameter. Values presented are the average of radial and tangential penetrations.
Hardwood: A description applied to woods from deciduous broad-leafed trees (Angiosperms). The term has no reference to the actual hardness of the wood. This does not refer to the actual hardness of the wood, but is a botanical term that distinguishes the wood of broad-leaved trees from that of conifers, which are considered softwood.
Healthy Knot: A solid wood knot that contains no bark or rot.
Heartwood: The inner layers of wood in growing trees that have ceased to contain living cells. Heartwood is generally darker than sapwood, but the two are not always clearly differentiated. Part right below the sapwood, in the core of the three. It is generally darked in color.
Herringbone: An arrangement of wood strips creating repetitive symmetrical patterns.
High-Density Fibreboard (HDF): A high-strength, engineered fibreboard designef for applications where increased strength is needed. Made by compressing wood fibres with resins under high pressure into an engineered substrate. Often used as an engineeered floating floor core material. HDF pressure is greater than 50 lbs. per cu. ft. or 800 kg per cubic metre.
Impact Bending: In the impact bending test, a hammer of given weight is dropped upon a beam from successively increased heights until rupture occurs or the beam deflects 152 mm (6 in.) or more. The height of the maximum drop, or the drop that causes failure, is a comparative value that represents the ability of wood to absorb shocks that cause stress beyond the proportional limit.
Joint Staggering: This term is self-explanatory. It is an important part of professional floor laying, and results in a tight and appealing-looking floor.
Lambs Wool Applicator: Floor finish applicator used on a pole for coating large areas.
Laminate: Material manufactured by pressing resin-impregnated fibers or sheets, then applying a top layer of a higher quality product.
Lap Marks: Refers to marks left from a brush or lambs wool applicator when finish is not applied evenly, or sometimes when climate conditions are not ideal.
Micro-V: The edge of a wood strip is originally cut at a right angle (90°). Just before the final sanding, the edge is cut at a 45° angle. When two strips are placed side-by-side, a small “V” shape is formed.
Medallion: A decorative design of parquet flooring assembled in the center of a room or in a high-visibility area. Many come factory-made, but they can be custom-made as well.
Medullary Rays: Striations that appear in some wood species when quartersawn. These are usually visible in oak with a golden color.
Mill Marks: Marks left on the flooring surface from the factory. Some manufacturers are better than others, which require little or sometimes moderate sanding.
Milling: This refers to all the shaping operations required before a strip is ready to sand and finish.
Modulus of Elasticity: An imaginary stress necessary to stretch a piece of material to twice its length or compress it to half its length. Values for the individual species are given in megapascals (MPa – equivalent to N/m2), and are based on testing small clear pieces of dry wood.
Modulus of Rupture: Reflects the maximum load-carrying capacity of a member in bending, and is proportional to maximum moment borne by the specimen. Modulus of rupture is an accepted criterion of strength, although it is not a true stress because the formula by which it is computed is valid only to the elastic limit.
Moisture Content (M.C.): The weight of water contained in wood expressed as a percentage of the weight of the oven dry wood.
Moisture Meter: A meter that is used to check the amount of moisture in wood. This is done to make sure flooring is not too wet or dry, thus preventing excessive expansion or contraction.
OSB: Oriented Strand Board.
Parquet: An assembly of wood strips in a square or rectangular pattern sometimes called a mosaic.
Peeled Veneer: Engineered wood flooring with peeled veneer is generally cheaper than sawn veneer flooring. It is made basically by peeling a log on a large lathe to produce a thin layer of wood for the flooring surface. Underneath that are layers of other woods sandwiched together at different angles to promote stability.
Pith Flecks: Pith-like irregular discolored streaks of tissue in wood, due to insect attack on the growing tree.
Plain-Sawn: The normal sawing process by which most flooring is produced.
Plywood: A board or panel made of multiple layers of wood glued cross-directionally for greater dimensional stability.
Polyurethanet: A large molecule of chemically joined urethane units. Can be irreversibly solidified or “cured” using heat, light, or other techniques.
Prefinished: Ready-to-install factory-finished flooring, compared to unfinished flooring, which requires on-site finishing (no sanding or finishing is necessary after installation).
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 such as cabinet faces or wainscoting. They will expand and contract less than boards sawn by other methods.
Radiant Heat: A heat source that is installed under finished flooring. Flexible tubing is installed in concrete or under the subfloor. Heated water is fed through the tubing, thus warming the flooring surface. This type of heating is relatively new to many contractors and builders. Great attention should be paid to wood flooring choice and installation procedures if radiant heat is desired.
Random Width: Wood flooring that is laid in a pattern of different widths.
Refinishing: The process of sanding a previously finished floor and applying a new finish.
Relative Humidity: The ratio between the amount of water vapor in the air and the air’s absorption capacity at a given temperature.
Resanding: Sanding a floor in order to remove the finish and restore the wood to its raw form.
Residential: We distinguish between floors installed for residential and commercial use, especially for the warranty. A location is considered commercial if it is open to the public or is a place of work. A residential location is one where people live. In residential locations, floors wear more slowly.
Rift-sawn: Rift-sawing at a 30-degree or greater angle to the growth rings produces narrow boards with accentuated vertical or “straight” grain patterns. Rift-sawn boards are often favored for fine furniture and other applications where matching grain is important. This type of lumber is available in limited quantities and species.
Rosin Paper: Pink paper that is laid down on top of the subflooring before installation of the wood floor itself to prevent squeaks.
Rotary Cut: A log peeled in ultra-thin layers using a rotary saw (method generally used to make veneers). This cutting method requires soaking the wood in a solution to soften it before peeling, which can alter its natural color and open the wood grain, causing it to splinter.
Sandscreens: Carbon-tipped mesh used on a buffer as a finish sanding to even out the smoothness of a floor. Also used between coats to smooth grain raise and to promote adhesion of coats.
Sapwood: The outer zone of wood in a tree, next to the bark. Sapwood is generally lighter than heartwood. Part of the three right under the bark, it is generally lighter in color.
Sanding: Polishing the surface of the wood.
Sawn Veneer: Refers to engineered wood flooring. It means that the top layer of wood is actually sawn. This is better than peeled veneer. It looks better, is more stable, and generally can be sanded, depending on the manufacturer.
Shear Strength Parallel to Grain: Ability to resist internal slipping of one part upon another along the grain. Values presented are average strength in radial and tangential shear planes.
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.
Sliced Cut: A wood block cut into thin sheets using a knife. This cutting method requires a presoaking process to soften the wood, which can alter its natural color and open the wood grain, causing it to splinter.
Solid: See related: Classic. Strips made entirely of natural wood.
Species: A specific variety of wood, like maple or oak. Some varieties include multiple species, such as red oak and white oak. The characteristics of a single species of wood can vary depending on the region. Oak grown in Nordic regions is harder than oak from the South.
Specific Gravity: The relative weight of a substance compared with that of an equal volume of water. The S.G. of wood is usually based on the green volume and oven dry weight.
Split: Separation of the fibers in a piece of wood from face to face (other term: end-split).
Square End: Refers to how flooring is made and sold. Some flooring comes with the ends of the boards already squared. Others (mainly unfinished flooring) have to be cut by the installer. Prefinished flooring normally comes either square end or square-microbeveled end.
Square Nose: A moulding constructed of wood or polymer, used to trim floating floors along walls around the perimeter of a room.
Squaring Up: Term for starting the first row of flooring parallel and perpendicular to walls in order to have the floor run in a straight line to the opposite wall.
Stability: Characteristic of a material that does not react, or reacts only very slightly, to ambient variations such as relative humidity.
Stain: Materials used to impart color to wood. A substance used to give wood a specific color. Another name is Staining.
Strips: Flooring boards to be installed in parallel rows, manufactured in various thicknesses and widths. Strips are connected with a tongue and groove joint.
Stop Mark: A gouge that is left when the operator stops moving as a drum or belt sander is running. Normally caused by amateurs, rarely seen when professionals do the work.
Subfloor: A floor base on which the floor covering is installed.
T-Moulding: A T-shaped moulding constructed of wood or polymer used to join floating floor tiles or planks of the same height together in dorrways between rooms. Also used in single large rooms where the distance is extreme and a mid-way joint is required for proper stability of floating floor tiles or planks.
Tensile Strength Perpendicular to Grain: Resistance of wood to forces acting across the grain that tend to split a member. Values presented are the average of radial and tangential observations.
Texture: Determined by relative size and distribution of the wood elements. Described as coarse (large elements), fine (small elements) or even (uniform size of elements).
Tongue: In wood strips with a tongue and groove joint, a tongue is milled on one edge of the strip and a groove is cut into the opposite edge. The form of the joint is also referred to as male (tongue) or female (groove). When the flooring is installed, the tongue of each strip is inserted into the groove of the adjacent strip.
Traditional: See related: Grade. An unfinished product that must be stained or finished after installation. Traditional is also grade of wood with the heaviest natural variation in color.
Ultraviolet-cured polyurethane: A special kind of polyurethane cured using ultraviolet light.
Underlayment: Foam or other material such as Cork (which is also used as a sound barrier) and laid over an existing floor or subfloor. Floating floor planks or tiles are installed on top of the underlayment material.
Unfinished: Flooring that must be sanded and finished after installation.
Uniclic Joint: The joint system patented by Unilin Decor of Belgium. A glueless tongue-and-groove design milled to tolerances of 1/1000″ in which the lower lip exerts constant pressure at a 45-degree angle on the tongue, holding it in place by constant pretension.
Urethane: An ingredient in varnish.
UV ProtectionTM: For some natural wood species manufacturers finish provides UV ProtectionTM that slows and reduces the sunshading phenomenon that causes wood to darken and yellow over time.
Varnish: A solution that leaves a thin layer of protection on the wood after curing.
Warp: Distortion in lumber causing departure from its original plane, usually developed during drying. Warp includes cup, bow, crook and twist.
Wear layer: The surface of a wood strip, which can be resanded after wear to restore the floor’s original appearance. Wear is generally very superficial. A 5/32″ (4 mm) thick wear layer is thick enough for many resandings.
Wear Resistance: The ability of the surface protection (such as aluminum oxide or urethane) that has been applied to either the decor layer or the wear layer, to withstand normal traffic.
Weight: The weight of dry wood depends upon the cellular space, the proportion of wood substance to air space.
Work to Maximum Load in Bending: Ability to absorb shock with some permanent deformation and more or less injury to a specimen. Work to maximum load is a measure of the combined strength and toughness of wood under bending stresses.
