Abrasion Resistance That property of a surface that resists being worn away by a rubbing or
friction process. Abrasion resistance isn't necessarily related to hardness, as believed by some,
but is more closely comparable to, or can be correlated with, toughness.
Acclimation The act of allowing wood moisture content to become at equilibrium with the
environment in which it will perform. (See EMC, Equilibrium Moisture Content)
Acid Chemical substance rated below 7 on the PH scale.
Air-Dried Dried by exposure to air in a yard or shed without artificial heat. (Not kiln dried)
Alkalinity A measurement of an alkaline rating about 7 on the PH scale.
Annual Growth Ring The layer of wood growth formed on a tree during a single growing season.
Asphalt Saturated Felt Paper A #15 asphalt felt paper that meets ASTM Standard D-4869 or
asphalt laminated paper that meets federal specification UU-B-790a Grade B, Type I, Style 1a, or
asphalt saturated paper that meets federal specification UU-B-790a, Grade D, Type I, Style 2.
Commonly used as a vapor retarder.
ASTM (American Society for Testing and Materials) develops and publishes voluntary technical
standards for a wide range of materials, products, systems, and services. ASTM uses a
consensus process involving technical committees that draw their members from around the
world. ASTM International has no role in requiring or enforcing compliance with its standards, but
in many instances its standards have been adopted by rules-making industry and governmental
ASTM F-2170 Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs
Using In Situ Probes.
ASTM F-1869 Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor
Using Anhydrous Calcium Chloride.
ASTM (modified) D-4944-043. Calcium Carbide (CM) Test.
Base Shoe A molding designed to be attached to baseboard molding to cover expansion space.
It is the alternative to a quarter-round in profile.
Bastard Sawn See Rift Sawn.
Beveled Edge The chamfered or beveled edge of wood flooring, plank, block and parquet.
Board Foot A unit of measurement of lumber represented by a board 1 foot long, 12 inches wide
and 1 inch thick or its cubic equivalent. In practice, the board foot calculation for lumber 1 inch or
more in thickness is based on its nominal thickness and width and the actual length. Lumber with
a nominal thickness of less than 1 inch is calculated as 1 inch.
Borders Simple or intricate designs which frame and customize a flooring installation.
Bow The distortion of lumber in which there is a deviation, in a direction perpendicular to the flat
face, from a straight line from end to end of the piece.
Burl A swirl or twist of the grain of the wood that usually occurs near a knot, but doesn't contain a
knot, commonly found in the stump of a tree and where limbs branch out from the tree.
Chatter Marks Slight, closely spaced indentations causing a ripple effect on the surface of a
Check A lengthwise separation of the wood that usually extends across the rings of annual
Checking (finish) Similar to alligatoring, except that the finish is broken into smaller segments.
Crowfoot checking is the name given to the defect when the breaks in the film form a definite
three-prong pattern with the breaks running outward from a central point of intersection. When the
checks are generally arranged in parallel lines, the defect is known as line checking. Irregular
checks without a definite pattern are known as irregular checking.
Cleat A barbed fastener commonly used as a mechanical device to fasten hardwood flooring.
Color Change Visual changes in the color of the wood species caused by exposure to light,
deprivation of light and air, or some chemical reaction.
Compression Set Caused when wood strips or parquet slats absorb excess moisture and
expand so much that the cells along the edges of adjoining pieces in the floor are crushed. This
causes them to lose resiliency and creates cracks when the floor returns to its normal moisture
Coniferous See Softwoods.
Crook The distortion of a board in which there is a deviation, in a direction perpendicular to the
edge, from a straight line from end to end of the piece.
Cross Directed Laying of material perpendicular to the material below it.
Crowning A convex or crowned condition or appearance of individual strips with the center of the
strip higher than the edges. The opposite of cupping.
Cupping A concave or dished appearance of individual strips with the edges raised above the
center. The opposite of crowning.
Deciduous See Hardwoods.
Deformed fasteners Fastener in which the sides are not smooth and the head shape may be
irregular. Examples are ring-shank and screw-shank nails.
Delamination The separation of layers in an engineered wood floor, through failure within the
adhesive or between plies. Also between layers of stain and/or coating.
Diffuse-Porous Woods Certain hardwoods 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. Hard maple is an example.
Dimensional Stability The ability to maintain the original intended dimensions when influenced
by a foreign substance. Wood is hygroscopic (readily takes up moisture) and isn't dimensionally
stable with changes in moisture content below the fiber saturation point. Engineered wood
flooring, however, is more dimensionally stable than solid wood.
Distressed A heavy artificial texture in which the floor has been scraped, scratched or gouged to
give it a time-worn antique look.
Drywall Interior covering material (such as gypsum board, hardboard or plywood) that is applied
in large sheets or panels.
Durability The ability of the wood species or finish to withstand the conditions or destructive
agents with which it comes in contact in actual usage, without an appreciable change in
appearance or other important properties.
Eased Edge See Beveled Edge.
End Joint The place where two pieces of flooring are joined together end to end.
End Lifting A swelling of the top layer of engineered wood flooring, occurring at an end joint.
End-Matched In tongue-and-groove strip and plank flooring, the individual pieces have a tongue
milled on one end and a groove milled on the opposite end, so that when the individual strips or
planks are butted together, the tongue of one piece fits into the groove of the next piece. See
Side-Matched and Tongue-and-Grooved.
Engineered An assembly made by bonding layers of veneer or lumber with an adhesive so that
most adjacent layers have their grains going in perpendicular directions to increase dimensional
Equilibrium Moisture Content (EMC) The moisture content at which wood neither gains nor
loses moisture when surrounded by air at a given relative humidity and temperature.
Fading The loss of color due to exposure to light, heat or other destructive agents.
Feature Strip A strip of wood used at a threshold or to border a room or to otherwise serve as an
accent. Usually of a contrasting color or species.
Fiberboard A broad generic term inclusive of sheet materials of widely varying densities
manufactured of refined or partially refined wood or other vegetable fibers. Bonding agents and
other materials may be added to increase strength, resistance to moisture, fire or decay, or to
improve some other property.
Fiber Saturation Point The stage in drying or wetting wood at which the cell walls are saturated
with water and the cell cavities are free from water. It's usually taken as approximately 30 percent
moisture content, based on over-dry weight.
Figure Inherent markings, designs or configurations on the surface of the wood produced by the
annual growth rings, rays, knots and deviations from regular grain.
Filler In woodworking, any substance used to fill the holes and irregularities in planed or sanded
surfaces to decrease the porosity of the surface before applying finish coatings. Wood filler used
for cracks, knotholes and worm holes is often a commercial putty, plastic wood or other material
mixed to the consistency of putty. A wood filler also may be mixed on the job using sanding dust
from the final sanding, or other suitable material, mixed with a product appropriate for this use.
Fillets The small components that comprise finger-block parquet. Also called fingers or slats.
Fillet may also refer to the top layer of some engineered wood flooring.
Fingers See Fillets.
Finger-block Parquet made from small strips of wood assembled together. See Fillets.
Fire Retardant A chemical or preparation of chemicals used to reduce flammability or to retard
the spread of a fire over a surface.
Flag A heavy dark mineral streak shaped like a banner.
Flag Worm Hole One or more worm holes surrounded by a mineral streak.
Flame Spread The propagation of a flame away from the source of ignition across the surface of
a liquid or solid, or through the volume of a gaseous mixture. NOTE: Most wood species are
Class C Flame Spread unless the wood floor has been treated and marked as to flame spread.
Flecks The wide irregular, conspicuous figure in quartersawn oak flooring. See Medullary Rays.
Floating Floor A floor that does not need to be nailed or glued to the subfloor. Typically, the
flooring panels are connected together by adhesive or mechanical connectors.
Flow The characteristic of a coating that allows it to level or spread into a smooth film of uniform
thickness before hardening.
Graininess The objectionable appearance of small, grain-like particles in a finishing material or in
the dried film thereof.
Hardened Steel Pin Specialty fasteners designed to penetrate and hold concrete, steel and other
substrates. Steel pins are typically installed with powder, pneumatic or gas-powered tools.”
Hardness That property of the wood species or dried film of finishing material that causes it to
withstand denting or being marked when pressure is exerted on its surface by an outside object
Hardwood Generally, one of the botanical groups of deciduous trees that have broad leaves, in
contrast to the conifers or softwoods. The term has no reference to the actual hardness of the
Heartwood The wood extending from the pith to the sapwood, the cells of which no longer
participate in the life processes of a tree. It is usually darker than sapwood. See Pith and
Heavy Streaks Spots and streaks of sufficient size and density to severely mar the appearance
Honeycombing Checks often not visible at the surface that occur in the interior of a piece of
wood, usually along the wood rays.
Humidity The amount of water vapor in the air. See Relative Humidity.
Hygrometer An instrument for measuring the degree of humidity or relative humidity of the
Hygroscopic A substance that can absorb and retain moisture, or lose or throw off moisture.
Wood and wood products are hygroscopic. They expand with absorption of moisture and their
dimensions become smaller when moisture is lost or thrown off.
In Situ A Latin term that means “in place” or “on site,” the term applies to testing done on site, or
on materials in their original location, as opposed to testing done in a laboratory. Some sound-
control testing is done in the field or “in situ,” and moisture testing of concrete slabs is often done
using “in situ” probes.
Intensity The intensity of a color is its purity or degree of hue as seen by the eye.
Jointed Flooring Strip flooring, generally birch, beech, hard maple or pecan, manufactured with
square edges, not side-matched, but usually end-matched. It is used principally for factory floors
where the square edges make replacement of strips easier.
Joist One of a series of parallel beams used to support floor or ceiling loads and supported in
turn by larger beams, girders or bearing walls.
Kiln (often pronounced "kill") A chamber having controlled air flow, temperature and relative
humidity for drying lumber, veneer and other wood products.
Kiln-Dried Dried in a kiln with the use of artificial heat.
Knot The portion of a branch or limb that has been surrounded by subsequent growth of the
stem. The shape of the knot as it appears on a cut surface depends on the angle of the cut
relative to the long axis of the knot. In hardwood strip flooring, small and pin knots aren't more
than one-half inch in diameter. A sound knot is a knot cut approximately parallel to its long axis so
that the exposed section is definitely elongated.
Manufacturing Defects Includes all defects or blemishes that are produced in manufacturing,
such as chipped grain, torn grain, skips in dressing, hit-and-miss (a series of surfaced areas with
skips between them), variation in machining, machine burn, and mismatching.
Mechanic A flooring installer, sander or finisher.
Medullary Rays Strips of cells extending radially within a tree and varying in height from a few
cells in some species to four or more inches in oak. The rays serve primarily to store food and
transport it horizontally in the tree. On quartersawn oak, the rays form a conspicuous figure
sometimes referred to as flecks. See Flecks.
Mineral Spirits A solvent product used as a thinner and/or cleaner.
Mineral Streak Wood containing an accumulations of mineral matter introduced by sap flow,
causing an unnatural color ranging from greenish brown to black.
Mixed Media A wood floor that is predominately of wood, but also incorporates other materials,
such as slate, stone, ceramic, marble or metal.
Moisture Content the amount of moisture in wood expressed as a percentage of the weight of
oven-dried wood. National Oak Flooring Manufacturers Association hardwood flooring is
manufactured at 6 to 9 percent moisture content, with a 5 percent allowance for pieces up to 12
percent moisture content. Five percent of the flooring may be outside of this range.
Muratic Acid A diluted acid used to neutralize alkalinity of concrete subfloors.
Nailing Shoe (or Nailing Plate) An attachment to a blind-nailing machine that broadens the
impact area. Often required for fastening factory-finished flooring.
Nominal Size As applied to timber or lumber, the size by which it is known and sold in the
market; often different from actual size.
Nosing A hardwood molding used to cover the outside corner of a step, milled to meet the
hardwood floor in the horizontal plane, to meet the riser in the vertical plane. It is usually used on
OSB Oriented Strand Board commonly used as an underlayment or subfloor material. Strands
tend to be oriented with their length aligned with the panel length (typically). OSB is therefore
stiffer and stronger when installed with the long axis across supports.
Overwood/Underwood A flooring condition in which there is a perceived misalignment of the
flooring surface, with some wood pieces raised above adjacent pieces leaving a slightly uneven
surface. Also called lippage.
Parquet A patterned floor.
Particleboard A generic term for a material manufactured from wood particles or other ligno-
cellulosic material and a synthetic resin or other suitable binder. Flakeboard is a particle panel
product composed of flakes. Oriented strand board is a type of particle panel product composed
of strand-type flakes that are purposely aligned in directions that make a panel stronger, stiffer
and with improved dimensional properties in the alignment directions than a panel of random
flake orientation. Waferboard is a particle panel product made of wafer-type flakes. It is usually
manufactured to possess equal properties in all directions parallel to the plane of the panel.
Photo-sensitive The property of some wood species which causes them to lighten or darken
when exposed to light. See color change.
Pin-Worm Hole In hardwood flooring, a small round hole not more than 1/16-inch (1.5626MM) in
diameter, made by a small wood-boring insect.
Pith The small, soft core occurring near the center of a tree trunk, branch, twig or log. First
Plain Sawn The annual growth rings make an angle of less than 45° with the surface of the
piece. This exposes the pores of the springwood and dense summerwood of the annual growth
ring in ring-porous woods to produce a pronounced grain pattern.
Planer Bite A deeper than intended groove cut into the surface of a piece of wood by planer
Plank Solid or Engineered/ boards 3" and wider designed to be installed in parallel rows.
Plywood Board or panel made of cross-directional veneers and/or layers of wood for dimensional
Plugs Used to cover countersunk screws when installing wood flooring or for decorative
purposes in wood flooring.
Prefinished Factory-finished flooring that only requires installation.
Quartersawn The annual growth rings of wood form an angle of 45° to 90° with the surface of the
piece. In quartersawn strips, the medullary rays or pith rays in ring-porous woods are exposed as
flecks that are reflective and produce a distinctive grain pattern.
Raised Grain A roughened or fuzzy condition of the face of the flooring in which the dense
summerwood is raised above the softer springwood but not torn or separated.
Rays, Wood See Medullary Rays.
Reducer Strip A teardrop-shaped molding accessory for hardwood flooring, normally used at
doorways, but sometimes at fireplaces and as a room divider. It is grooved on one edge and
tapered or feathered on the other edge.
Relative Humidity Ratio of the amount of water va