Hardwood Flooring Terms


Above Grade Any surface that is above the level of the surrounding ground.

Acrylic Impregnated Acrylic monomers are injected into the cell structure of the wood to increase hardness, then finished with a wear layer over the wood.

Acrylic Urethane Slightly different chemical composition than Polyurethane, with similar benefits.

Aluminum Oxide Added to the wear layer of a urethane finish for increased abrasion resistance. Popular on better grade wood floors.

Below Grade Any surface that is below the level of the surrounding ground.

Better A quality of oak that has small knots and light dark graining.

Beveled Edge Hardwood boards with a distinctive groove in them, as seen in informal and country decor. With today’s urethane finishes, these edges can be completely sealed, making these floors easy to clean.

Buckle When humidity is high, wood expands and gaps disappear. In situations of too much moisture, wood may cup, or “buckle.”

Clear A quality of oak that has no visual blemishes or knots. Expensive.

Cross-ply Construction A technique where wood plies are stacked on top of each other in opposing directions. The result is a wood floor that is dimensionally stable and less affected by moisture. Allows the plies to counteract each other, thus prohibiting the plank from shrinking or expanding under humid conditions. These floors can be installed over concrete and/or below grade.

Cupping Warping with a concave condition; the center is lower than the sides.

Eased Edge Some manufacturers add this slightly beveled edge to both the length and end joints of their hardwood planks. This helps hide minor irregularities, including uneven plank heights. Also called “micro-beveled edge.”

Engineered One of the three common types of hardwood floor (the others are Solid and Longstrip Plank). Generally made with 2,3, or 5 thin sheets or plies of wood, laminated together to form a single plank. Most can be nailed, stapled or glued down, or floated over a variety of subfloors, including some existing flooring.

Finish in Place The term given to unfinished hardwood floors that are installed onsite, sanded and finished with an application of 2 to 3 coats of urethane that is brushed or mopped on. May be screened and recoated to rejuvenate the finish and revitalize the floor’s natural beauty.

Floating Floor Installation With this method of installation, hardwood floors are not mechanically fastened to any part of the subfloor. Instead, a thin pad is placed between the wood and the subfloor and a recommended wood glue is applied in the tongue and groove of each plank. This technique protects against moisture, reduces noise, feels softer and provides for some additional “R” value. Some Engineered floors and all Longstrip floors can be floated.

Glue Down The process in which hardwood floor is adhered to a subfloor using a recommended mastic or adhesive, spread on with the proper sized trowel. Engineered wood floors and parquets are typically glued down, while solid strip and plank floors are nailed or stapled.

Graining Each species of wood has its own unique texture, color and graining, determined by the way it was cut.

Janka Hardness Test The standard test for determining a wood’s hardness rating in which the force required to embed a .444 inch steel ball to half its diameter in a piece of wood is measured. The higher the number, the harder the wood. Only used as a general guideline.

Knot The round, harder, typically darker cross section of a piece of wood where a branch once joined the tree trunk.

Laminate A manufactured product sandwiching a backing material, visual element and a wear layer that simulates the look of hardwood, stone, or other natural or unnatural  surfaces.

Longstrip Plank One of the three common types of hardwood floor (the others are Solid and Engineered). Similar to Engineered floors in that multiple layers or plies are glued together on top of a center core that is typically a softer wood material that is also used to make the tongue and groove. The result is a board that appears to be 3 rows wide and several planks long. Comes in a wide variety of domestic and exotic hardwood species. Easy to replace if damaged.

Moisture Cured Urethane A chemical similar to solvent-based urethanes, but requires humidity (moisture) to cure.  Extremely difficult to apply, has a strong odor and is best left to the professional.

Moldings Used to cover expansion joints and to enhance the performance and appearance of a hardwood floor. Typically need to be removed for installation.

Nail Down Nailing cleats are used with a wood flooring nailer and a mallet to attach hardwood flooring to a subfloor. This method of installation is typically used with the 3/4″ solid products, though adapters exist for thinner floors.

Number 1 Common A quality of oak that has some knots and some dark graining.

Number 2 Common A quality of oak that has even more knots and dark graining.

On-Grade At ground level.

Polyurethane A clear, durable finish applied as a wear layer over hardwood floor.

Pre-Finished Wood Hardwood flooring that comes sanded, stained and finished at the manufacturing plant, ready for installation in your home. These products typically provide a harder, better-protected surface because several coats of urethane are applied and UV dried. Offers a wider variety of wood species and saves hours of labor and cleanup. May be screened and recoated to rejuvenate the finish and revitalize the floor’s natural beauty.

Rotary Cut A hardwood cutting process that displays a larger and bolder graining pattern.

Select A quality of oak that has some small knots but very little dark graining.

Sliced Cut A hardwood cutting process that shows a more uniform pattern.

Solid One of the three common types of hardwood floor (the others are Engineered and Longstrip Plank). One solid piece of wood that has tongue and groove sides. Comes unfinished or pre-finished. Sensitive to moisture.

Solvent-Based Urethane Oil Used as part of the chemical composition of a polyurethane finish.

Square Edge When the edges of all hardwood boards meet squarely to create a uniform, smooth surface that blends the floor together from strip to strip or plank to plank.

Stapled Down A method of hardwood installation in which staples are used to attach the wood to the subfloor. A pneumatic gun is often used.

Strip The “classic” hardwood floor with narrower board widths. Most common species are red oak, white oak, maple, cherry, white ash, hickory and pecan.

Tongue and Groove The joining of two hardwood boards, one having a tongue on its edge that fits into the groove in the edge of the other.

Trim See “Moldings”

Un-Finished Wood Floor Not pre-finished in a factory. Allows you to have a customize your floor by sanding, staining/finishing it on site. Also see  “Finish in Place.”

UV Cured Hardwood finishes cured in a factory with Ultra Violet lights versus heat.

Water-Based Urethane A polyurethane finish that includes water in its chemical composition, dries clear and is non-yellowing.

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