Hardwood Flooring Reference Tool & Definitions

Hardwood Flooring Reference Tool & Definitions

Hardwood Flooring Reference Tool & Definitions

Quick reference guide for hardwood tools & definitions

Above Grade

Grade DiagramA suspended floor located above ground level, with a minimum of 18 inches of ventilated air space below. Normally above a basement, but a suspended floor may also be above a crawl space.

Abrasion Resistance

How well a surface resists being worn by rubbing or friction. Abrasion resistance does not describe hardness, but rather toughness.

Extra Resource: Article on World-Friendly Wood Finishes that will help enhance toughness of flooring.

AC Wear Layer

A durable wear layer that protects against wear, stains, and fading in laminate flooring.

Acclimation

Allowing the moisture content of new wood flooring to reach an equilibrium or balance with its surroundings before installation. (See Equilibrium Moisture Content, EMC)

Extra Resource: Article on Hardwood Floor Acclimation: When You Can Install

Acrylic Impregnated or Acrylic Infused

A generic term for wood-plastic composite flooring often used in commercial properties, acrylic impregnated wood is made by infusing wood with acrylic resin, so the color and finish are not only consistent on the surface, but throughout the wood as well. Although durable, acrylic impregnated wood floors cannot be refinished and are susceptible to water staining.

Adhesive

A substance that bonds the finished floor product to the substrate (the layer that underlies the floor product).

Air-Dried

Refers to wood dried by exposure to air (such as in a yard or shed) without artificial heat, as is used in kiln drying.

Aluminum Oxide

A protective coating for hardwood floors commonly used because of its strength (second in hardness to diamond).
Tree Growth Rings

Annual Growth Ring

The layer of wood growth formed on a tree during a single growing season.

Asphalt Saturated Felt Paper

Asphalt-saturated products are used as vapor retarders and typically come in rolls installed over the subfloor with the seams overlapping a minimum of 4 inches. Also referred to as #15 or #30 felt, asphalt saturated felt paper meets industry standard ASTM D4869.

ASTM

The American Society for Testing and Materials develops and publishes voluntary technical standards for a wide range of materials, products, systems, and services. Although ASTM International standards are not required or enforced, they have been adopted by rules-making industry and governmental bodies.

ASTM (modified) D-4944-043

Also known as the Calcium Carbide (CM) Test where a mid-depth sample of the screed is taken and allowed to react with calcium carbide reagent. Upon reacting, the mixture releases acetylene gas, the amount of which indicates the level of moisture in the sample.

ASTM F-1869

The American Society for Testing and Materials (ASTM) developed this standard test for determining the rate of moisture vapor emission from the surface of a concrete floor using anhydrous calcium chloride. All concrete subfloors emit some amount of moisture in vapor form, and all floor coverings are susceptible to failure from excessive moisture vapor emissions. The calcium chloride moisture test results are used to determine whether the floor is acceptable to receive resilient floor covering. The calcium chloride moisture test is the industry standard for making this determination and is a practical, well-established and accepted test of dynamic moisture.

ASTM F-2170

The American Society for Testing and Materials (ASTM) developed this standard test for determining relative humidity in concrete floor slabs using in situ probes (moisture testing sensors inside the slab itself). In-situ probes measure relative humidity (RH), providing a composite picture of overall slab moisture levels. Excessive moisture permeating from floor slabs after installation can cause floor covering delamination, peeling, blistering, staining and sweating.

Base/Shoe Combination

Molding piece used along the outer most edges of the floor where it meets the wall. The base/shoe combo is attached to baseboard molding to cover expansion space and is the alternative to a quarter-round in profile.

Bastard Sawn

See Rift Sawn.

Below Grade

Grade DiagramBelow ground level; partially or completely below the surrounding ground level and in direct contact with the ground or with fill which is in direct contact with the ground.

Beveled Edge

A type of wood flooring edge that has a “v” shaped groove commonly used in informal settings that can also help hide uneven subflooring or differences in plank thickness.

Blind Nailing

Putting nails into the grooves of tongue-and-groove flooring at a 45-degree angle.

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).

Board Width

The width of the individual wood boards that make up the floor. “Strips” are narrow boards measuring less than 3 inches wide. “Planks” measure more than 3 inches wide, and “wide planks” are more than 5 inches wide.

Borders

BoardersWood pieces in simple or intricate designs that frame and customize a flooring installation.

Bow

A type of warping or deviation from flatness in wood that is a result of stress and shrinkage from the uneven drying of lumber. A bow forms along the length of the face of the wood.

Bull Nose

A smooth, rounded trim installed where flooring meets wall.

Burl

A swirl or twist in wood grain that does not contain a knot. Burls are commonly found near knots and in tree stumps where limbs have branched out.

Chatter Marks or Chatter

Chatter marks on WoodA rippling pattern of half-circle marks that appear on hardwood floor surfaces as a result of improper sanding.

Check

A crack that occurs on the ends and surfaces of lumber during drying. Checking is caused by shrinkage differences between the surface and core of drying lumber. Since the ends and surfaces dry first, they tend to shrink first, but are restrained by the swollen core. This results in stresses building up near the surfaces which, if they become too great, cause the lumber to check.

Checking (finish)

Checking of finish of wood flooring appear as small, uniformly spaced cracks in the finish that run parallel with the grain of the wood. Checking is the result of stresses created from shrinking and swelling of the wood, usually caused by exposure to extreme heat or cold, or extremely dry or wet environment.

Cleat

A barbed fastener commonly used to fasten hardwood flooring.

Color Change

Color ChangeVisual changes in the color of wood. Most commonly caused by exposure to light, deprivation of light and air, oxidation or other chemical reaction.

Color Variation

A natural variation in light and dark tones of wood that appear from board-to-board.

Color Wash

Paint is thinned with glaze to create a subtle wash of color over hardwood floor.

Compression Set

Caused when wood strips or parquet slats absorb excess moisture and expand to the point that the cells along the edges of adjoining pieces in the floor are crushed. This results in cracking when the floor returns to its normal moisture content.

Extra Resource: Article on flooring problems that are moisture related

Coniferous

See Softwoods.

Crook

Warping along the length of the edge of a board causing a side bend. Crooks occur when one edge shrinks more in length than the other.

Cross Directed

Material laid perpendicular to the material below it.Engineered Hardwood Layers

Cross-ply Construction

Engineered hardwood created by stacking planks in alternating directions.

Crowning

Warping that causes the center of the wood board to appear higher than the edges. The opposite of cupping.

Extra Resource: Article on Cupping and Crowning

Cupping

Image from http://www.westcoasthardwoods.net/

Image from http://www.westcoasthardwoods.net

Warping that causes the sides of a wood board to appear higher than the center. The opposite of crowning.

Extra Resource: Article on Cupping and Crowning

Deciduous

See Hardwoods.

Deformed fasteners

Includes ring-shank and screw-shank nails.The sides of deformed fasteners are not smooth, and the head shape may be irregular

Delamination

delaminationThe separation of layers in an engineered wood floor or layers of stain and/or coating caused by failure within the adhesive or between plies.

Diffuse-Porous Woods

Describes certain hardwoods where the pores are either uniform in size and evenly distributed throughout the wood’s annual ring, or gradually decrease in size toward the outer border of ring. For example: hard maple, apple, cherry beech and holly.

Dimensional Stability

The ability of wood flooring to maintain its original dimensions throughout its lifetime.

Distressed

DistressedDesign term that describes wood flooring texture that has a time-worn, antique look achieved through scraping, scratching or gouging.

DIY (Do-It-Yourself)

Describes projects that can be installed without a professional. DIY levels vary from easy to difficult, depending on the necessary tools and experience.

Drywall

Interior wall and ceiling covering material also known as plasterboard, wallboard, gypsum board, or LAGYP. Drywall is made of gypsum plaster pressed between two thick sheets of paper that is applied in large sheets or panels.

Durability

Describes wood’s ability to withstand the conditions and destructive products it comes in contact with in actual usage without noticeable changes in its properties or appearance.

Eased Edge

A type of wood flooring edge that is shallower and more rounded than a “v”-shaped, beveled edge.

Edge Detail

Describes the way flooring board edges and ends are cut, typically square, eased, beveled or microbeveled.

End Joint

Where two pieces of flooring are joined together end to end.

End Lifting

Swelling of the top layer of engineered wood flooring at an end joint.

End-Matched

In tongue-and-groove flooring, the individual pieces have a tongue milled on one end and a groove milled on the opposite end. When butted together, the tongue of one piece fits into the groove of the next piece.

Engineered

engineered Wood FlooringA manufacturing process that bonds layers of veneer or lumber (or plies) with an adhesive in a cross-ply construction (where the wood grains are perpendicular to each other) in order to increase dimensional stability. The top layer is the wood species and color visible when installed.

Extra Resource: Article on Engineered Floors

Equilibrium Moisture Content (EMC)

The point at which wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.

Expansion

When moisture causes swelling and contracting, the dimensions of a wood floor change.

Extra Resource: Article on Expansion and Shrinkage in Wood

Expansion Gap

An area around the perimeter of a wood floor left open to account for expansion.

Expansion Spacing

Amount of space left at the baseboard to allow for expansion.

Extra Resource: Article on Shrinkage & Swelling

Face Nail

Nail Down Installation DiagramTechnique where nails are installed perpendicular to the surface of the wood flooring, rather than at a concealed angle (blind nailing).

Fading

Loss of color that results when wood flooring is exposed to light, heat or other destructive agents.

Feature Strip

Wood accent used at the threshold or borders of a room, usually of a contrasting color or species.

Fiberboard

Engineered wood made of wood fibers, including particle board, medium-density fiberboard (MDF), and hardboard. For pieces that will be visible, a veneer of wood is often glued onto fiberboard to give it the appearance of conventional wood.

Fiber Saturation Point

When wood’s cell walls are saturated with water, and the cell cavities are free from water. This is usually taken as approximately 30 percent moisture content, based on oven-dry weight.

Figure

Naturally occurring markings or designs on surface of wood produced by annual growth rings, knots or other deviations in the regular grain.

Filler

A substance used in woodworking to fill holes and irregularities in planed or sanded surfaces before applying finish coatings. Wood filler is often a commercial putty, plastic wood or other material mixed to the consistency of putty.

Filled Face

A smooth, piano-like finish on wood.

Fillets

Small components that make up finger-block parquet, also called fingers or slats. Fillets can 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.

Finish

The surface coating on pre-finished hardwood flooring, usually either a UV-cured urethane or UV-cured urethane with aluminum oxide finish. On laminate, finish is a clear wear layer that protects from high abrasion, fading, stains and wear-through.

Extra Resource: Article on World-Friendly Wood Finishes

Fire Resistance

The property of a material to withstand fire. Certain wood species naturally provide greater fire resistance than others. Classes are I-II-III or A-B-C, with Class I or A being the most fire resistant.

Fire Retardant

A chemical used to reduce flammability or to retard the spread of a fire over a surface.

Flag

A heavy dark mineral streak in wood that is shaped like a banner.

Flag Worm Hole

Flag Worm HoleOne or more worm holes surrounded by a mineral streak.

Flame Spread

Also known as surface burning characteristics rating, flame spread is a ranking of a material’s propensity to burn rapidly and spread flames. The best known test for developing this rating is the American Society for Testing and Materials (ASTM) Test Method E-84, commonly known as the tunnel test.

Flat Sawn (Plain Sawn)

When lumber is cut from logs, it is typically cut in one of three ways: quarter sawn, rift sawn or flat (plain) sawn, depending on how the log is oriented to the saw. Flat sawn is cut into long planks where the rings run parallel to the board and is the most common and least expensive wood.
Flecks

Flecks

Quarter sawn wood (particularly oak) will also often display a pattern of flecks in subtle ribbon-like patterns across the straight grain. This ray pattern has made quarter sawn wood especially desirable for furniture and decorative paneling. See Medullary Rays.

Floating Floor

Floating FloorFlooring panels that are connected together by adhesive or mechanical connectors and therefore do not need to be nailed or glued to a subfloor.

Flow

How a floor coating levels or spreads into a smooth, uniform film and thickness before hardening.

Flush Reducer

A wood molding that provides a gradual transition between floor surfaces of different heights and from room to room.

Flush Stair Nose

A wood molding that provides a smooth transition between the riser edge and the hardwood flooring on a step.

Foam Underlayment

Installed under flooring to reduce sound and smooth minor subfloor irregularities.

Forest Stewardship Council (FSC)

An independent, non-governmental, non-profit organization that promotes the responsible management of the world’s forests.

Gloss Level

How reflective a dry film is. Used interchangeably with “sheen,” gloss level can affect a paint’s color. Levels include: high gloss, semi-gloss, low gloss, and ultra-low gloss.

Grade Level

Describes the level of construction relative to the ground around it. Below grade is below ground level, on grade is at ground level, and above grade is above ground level.

Grain

Wood GrainThe visible lines in wood that show natural growth rings.

Graininess

The objectionable appearance of small, grain-like particles in a finishing material.

Hand-scraped or Hand Sculpted

Boards are individually scraped to create unique, one-of-a-kind flooring.

Hardened Steel Pin

Specialty fastener designed to penetrate and hold concrete, steel and other substrates, typically installed with powder, pneumatic or gas-powered tools.

Hardness

Describes how wood or finishing material withstands denting or marking when pressure is exerted on it.

Hardwood

Wood of deciduous, broadleaved trees (such as oak, ash, or beech) as opposed to that of conifers, or softwoods. The term does not refer to the actual hardness of the wood.

Heartwood

http://www.westcoasthardwoods.net/definitions.html

http://www.westcoasthardwoods.net/definitions.html

The non-living, central wood of a tree that is usually darker than sapwood, stronger and more resistant to decay.

Heavy Streaks

Marks on wood that are of sufficient size and density to severely mar its appearance.

High-density Fiberboard (HDF)

Used to make engineered hardwood, HDF is made by compressing fibers of wood chips with an adhesive to create a board that is more stable than plywood.

High-pressure Laminate (HPL)

High Pressure Laminate (HPL)Process for making laminate flooring in which the surface, inner layers and backing are fused in a multi-step press operation.

Honeycombing

Check damage on wood’s interior fibers often not visible at the surface. Honeycombing occurs during the final drying stages, when internal fibers begin to separate against the wood grain, causing structural weakening without being visible from the outside.

Humidity

The amount of water vapor in the air. See Relative Humidity.

Hygrometer

HygrometerAn instrument for measuring the degree of humidity or relative humidity of the atmosphere.

Hygroscopic

A substance’s ability to absorb and retain moisture, or lose or resist moisture. Wood is hygroscopic, as it expands with absorption of moisture and its dimensions become smaller when moisture is lost.
Extra Resource: Hygroscopic: What That Means For Your Floor

In Situ

A Latin term that means “in place” or “on site.” Moisture testing of concrete slabs is often done using “in situ” probes. See ASTM F-2170.
Extra Resource: ASTM F-2170 Explained

Installation Level

The grade of levels of the installation site.

Interlocking (Interlocking Floating)

Interlocking FlooringFlooring panels that are connected together by mechanical connectors and therefore do not need to be nailed or glued to a subfloor. See Floating Floor.

Intensity

A color’s purity or degree of hue as seen by the eye.

Janka Hardness

A hardness rating for wood species determined by the amount of force it takes to drive a .444 inch steel ball into a plank of wood .222 inches in diameter.
Extra Resource: Hardness Testing

Jointed Flooring

Strip flooring manufactured with square edges and no tongue or groove that is usually end-matched. Used principally for factory floors where the square edges make replacement of strips easier, jointed flooring is usually birch, beech, hard maple or pecan.

Joist

Construction JoistsA length of timber or steel that supports part of the structure of a building, typically arranged in parallel series to support a floor or ceiling.

Kiln

A chamber that uses artificial heat for drying lumber and other wood products. Kilns have controlled air flow, temperature and relative humidity.

Kiln-Dried

Refers to wood dried in a kiln. See Kiln.

Knot

Knot in WoodThe portion of a branch or limb that has been surrounded by subsequent growth of the trunk or other portions of the tree. A knot appears on the sawed surface but is merely a section of the entire knot, its shape determined by the angle or direction of the cut.

Lacy Act

Prohibits all trade in plant and plant products illegally sourced from any U.S. State or foreign country.
Read & Find Out More Here

Locking Floating/Locking Installation System

See Floating Floor.

Lumber Grade

The National Oak Flooring Mfg. Assoc. (NOFMA) standard grading system for unfinished flooring that determines how many defects are acceptable in wood sold.

Manufacturing Defects

Defects in lumber produced during manufacturing. The machining process to produce dimensional lumber puts a large amount of stress on wood causing defects such as chipped grain, torn grain, skips in dressing, hit-and-miss (a series of surfaced areas with skips between them), variations in machining, machine burn, and mismatching.

Material Safety Data Sheet (MSDS)

Material Safety Data SheetsLists information on the potential hazards (health, fire, reactivity and environmental), safety precautions and first aid information relating to chemical products.

Mechanic

A flooring installer, sander or finisher.

Medullary Rays

See Flecks.

Micro Bevel Edge

Features a v-shaped groove shallower than the bevel edge and provides just enough relief on the edges of the board to eliminate edge splitting and micro variations in finished board heights. A micro beveled edge will most likely disappear when the hardwood floor is refinished.

Mineral Spirits

Solvent used as a thinner and/or cleaner.

Mineral Streak

http://www.westcoasthardwoods.net/definitions.html

http://www.westcoasthardwoods.net/definitions.html

An unnatural color ranging from greenish brown to black that forms in wood through accumulations of mineral matter from sap flow.

Mixed Media

Incorporating multiple materials in one piece of furniture, art, or installation. For example, wood flooring with slate, stone, ceramic, marble or metal accents.

Moisture Content

The amount of moisture in wood expressed as a percentage of the weight of oven-dried wood. The moisture content of wood is tied directly to the relative humidity of the surrounding air. The higher the relative humidity, the higher the MC of the wood.
Extra Resource: Video on Relative Humidity and Moisture Content

Moldings

Wood trim or transition pieces that finish the look of an installed floor.

Muratic Acid

A diluted acid used to neutralize alkalinity of concrete subfloors.

Nail Down

A flooring installation method that uses nails to attach flooring to a subfloor.

Nailing Shoe (or Nailing Plate)

Often required for fastening factory-finished flooring, a nailing shoe attaches to a blind-nailing machine to broaden the impact area.

Natural Stain

Clear wood finish that allows the natural colors and grain to show.

Nominal Size

The size by which lumber is known and sold in the market.

Nosing

A type of wood molding used to cover the outside corner of a step, usually used on landings. Nosing is milled to meet the hardwood floor in the horizontal plane and to meet the riser in the vertical plane.

NWFA

National Wood Flooring Association

Oriented Strand Board (OSB)

OSB is a structural engineered wood manufactured from waterproof heat-cured adhesives and rectangular-shaped wood strands arranged in cross-oriented layers. This results in strength and performance characteristics similar to plywood. OSB is commonly used as an underlayment or subfloor material.

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

Parquet FloorA patterned floor created by inlaid woodwork in geometric forms, sometimes of contrasting woods.

Particleboard

Also known as chipboard, an engineered wood product manufactured from wood chips, sawmill shavings, or sawdust and a synthetic resin or other binder that is pressed and extruded. Particleboard is a composite material and includes Flakeboard, Oriented Strand Board and Waferboard.

Patina

The change in wood color from light exposure and other natural elements over time.

Photo-sensitive
The extent to which a wood flooring’s natural color will lighten or darken after long-term exposure to natural light.

Pin-Worm Hole

Pin-Worm HoleA small round hole in hardwood flooring, 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
growth.

Plain Sawn

See Flat-Sawn.

Planer Bite

Results when a planer knife cuts a deeper than intended groove into the surface of the wood.

Plank

Solid or Engineered boards 3″ and wider designed to be installed in parallel rows.

Plugs

Used in wood flooring to cover countersunk screws or for decorative purposes.

Ply (plies)

A layer of wood, typically used to describe engineered hardwood construction layers.

Plywood

Plywood for SubflooringA structural material consisting of cross-directional veneers and/or layers of wood glued cemented together for dimensional stability and used as underlayment for vinyl flooring.

Polyurethane

A type of protective finish that does not require waxing commonly used on hardwood flooring.

Prefinished

Hardwood floors that are stained with color and sealed with a protective finish by the manufacturer prior to installation.

Printed Construction

A printing process that provides accurate reproductions of a wide variety of patterns and designs in intricate detail. Also known as the “rotogravure” process.

Pull Bar

Tool used to tighten tongue and groove joints when installing laminate flooring.

Quarter Round Molding

Molding used between cabinets and flooring to cover gaps.

Quarter Sawn

Quarter Sawn DiagramWhen lumber is cut from logs, it is typically cut in one of three ways: quarter sawn, rift sawn or flat (plain) sawn, depending on how the log is oriented to the saw. In quarter sawn, the log is first quartered lengthwise, resulting in wedges with a right angle ending at approximately the center of the original log. Each quarter is then cut separately, resulting in boards with the annual rings mostly perpendicular to the faces and a distinctive ray and fleck figure.

Radiant Heating

Typically installed under stone and ceramic floors to keep floors at a comfortable temperature.

Raised Grain

The dense summerwood is raised above the softer springwood resulting in a face finish that is rough to the touch.

Random Length/Width

Flooring sold in cartons where boards are different lengths or widths.

Rays, Wood

See Flecks.

Reclaimed Wood

Reclaimed WoodWood salvaged from an old structure that is refinished and used for another purpose, such as floors, cabinetry or furniture.

Reducer Strip

Molding that is grooved on one edge and tapered or feathered on the other. Used to finish the space between hardwood flooring and other flooring surfaces.

Refinish

Sanding down a wood floor and finishing it again in order to reduce the appearance of wear or change the stain color.

Relative Humidity

The amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature. Relative humidity is usually considered on the basis of the weight of the vapor, but for accuracy should be considered on the basis of vapor pressures.
Extra Resource: Accurate Relative Humidity Testing Article

Rift Sawn

Rift Sawn DiagramWhen lumber is cut from logs, it is typically cut in one of three ways: quarter sawn, rift sawn or flat (plain) sawn, depending on how the log is oriented to then saw. Rift sawn is the most expensive and least common, manufactured by sawing perpendicular to the log’s growth rings and resulting in a linear grain pattern with no flecking.

Ring-Porous Woods

Ring-Porous WoodA group of hardwoods in which the pores are comparatively large at the beginning of each annual growth ring and decrease in size toward the outer portion of the ring. The large pores are springwood and the smaller pores are summerwood.

Ring Shank Nail

A type of nail with either annual or helical threads in the shank that have smaller diameters than common nails of similar length. Ring shank nails are used for underlayment installation to improve the holding characteristics.

S4S (Surface-4-Sides)

Flooring that isn’t tongue-and-grooved. May also refer to square-edge strip flooring that is face-nailed when installed.

Sapwood

A tree’s new wood used for moving water and minerals into the leaves. As newer rings of sapwood are produced, its inner cells lose their vitality and turn into heartwood.

Sawn

Plain Sawn DiagramSee Flat Sawn, Quarter sawn and Rift Sawn.

Screed

Usually a 2″ by 4″ inch piece of wood laid flat side down and attached to a concrete subfloor to provide a nailing surface for tongue-and-groove strip flooring or a wood subfloor (also called sleeper).
Shake

Shake

A separation along the grain of wood, the greater part of which occurs between the annual growth rings.

Sheathing

SheathingSheets of plywood placed over the exterior studding, rafters or subfloor of a structure.

Shoe Molding

Humidity-resistant molding for high traffic areas.

Side-Matched

In tongue-and-groove flooring, the individual pieces have a tongue milled on one side and a groove milled on the opposite side. When placed side-by-side, the tongue of one piece fits into the groove of the next piece. See End-Matched and Tongue-and-Groove.

Site-finished

Hardwood floors that are stained with color and sealed with a protective finish at the installation site, as opposed to pre-finished.

Slats

See Fillets.

Sleeper

Another name for screeds.

Slip-Tongue/Spline

A small strip of wood or metal used to reverse or change direction in installing standard tongue-and-groove strip flooring.

Softwoods

Wood of coniferous, needle/cone bearing trees as opposed to that of deciduous, or hardwoods. The term does not refer to the actual softness of the wood.

Solid Board Group 1

A designation of a certain species of wood based on density, strength and stiffness.

Solid Wood

Boards manufactured from one piece of wood, unlike engineered wood, which is formed from multiple plies.

Species

Refers to the many types of wood, such as oak, cherry or walnut, differentiated by wood grain, density, color and more.
Extra Resource: Article on Wood Species

Specifications

The detailed selections of the architect, covering all of the material and labor methods to be used in erecting a building. Usually prescribe types of material, sources, and often lists method of application or installation.

Split

SplitSeparations of wood fiber running parallel to the grain.

Square Edge

Edges of boards created to lay flush to the next board in order to decrease the appearance of lines between boards.

Square Nose

Trim used along the walls of floating floors.

Squares

Parquet flooring units, usually composed of an equal number of slats.

Stair Nosing

Molding applied to the forward edge of stairs, step-downs, and landings, creating a rounded finish.
Mineral Streak

Streaks

See Mineral Streaks.

Strip Flooring

Boards less than 3 inches in width installed in parallel rows. The strips are side-matched and end-matched (tongue-and-grooved) and are for nail-down installation directly to wood or plywood subfloors, or over wood screeds on concrete slab construction.

Structural Integrity

A term often used in a guarantee or warranty to assure the floor’s composition/construction will remain intact.

Subfloor

Man Nailing plywood subfloorThe structural layer intended to provide the home’s floor support, which may receive floor coverings directly if the surface is appropriate, or indirectly via an underlayment if its surface is not suitable.

Substrate

A smooth surface used beneath floor covering – such as concrete, underlayment, or existing resilient flooring.

Suspended Substrate

Location of a finished floor that is not in contact with the ground and which provides at least 18 inches of well-ventilated space.

Surface

The outside or exterior boundary of any substance. One is said to surface the work when it is rubbed or sanded to a smooth, level plane.

Taber

Measure of the wear of flooring through resistance.

Texture

Flooring surface’s look and feel, which can range from silky smooth to distressed.

Threshold

Finishing piece applied to the area where a wood floor transitions to another flooring level or another flooring type.

T-Molding

Piece that finishes the space between two areas of wood flooring.

Tongue-and-Groove

A tongue is milled on one edge of a flooring board, and a groove is cut on the opposite edge. As the flooring is installed, the tongue of each strip fits into the groove of the adjacent strip. See End-Matched and Side-Matched.

Trim

Finish materials used at the floor of rooms, such as baseboard, base shoe, quarter
Round.

Trowel Fill

Method to fill an entire floor or large area.

Truss

Support that helps keep floors level and sturdy.

Transition Strips

Wood piece that bridges two floors of different heights to equalize them.

Ultraviolet Light

Part of the light spectrum that cannot be seen by the human eye.

Underlayment

Layer of material installed on or over a subfloor that provides a surface suitable to receive a new floor covering.

Vapor Impermeable Membrane

A material or covering that limits the passage of moisture and has a permeance rating of .15 perms or less.
Extra Resource: Article on Vapor Barrier/Vapor Retarder

Vapor Permeable Membrane

A material or covering that permits the passage of moisture and has a permeance rating of 5 perms or greater. See Vapor Retarder.

Vapor Retarder

A material or covering that slows the rate of moisture movement to the hardwood to protect the flooring and reduce or prevent cupping or other moisture-related problems. National Wood Flooring Association (NWFA) guidelines define an acceptable vapor-retarder as having a vapor permeance (or perm rating) between 0.7 and 50.
Extra Resource: Article on Vapor Barrier/Vapor Retarder

Varnish

A finish made of oils that are cured slowly over time.
Tip: Close windows of the room you are varnishing to prevent layers of dust and insects from collecting on fresh varnish.

Veneer

A thin layer of real hardwood glued to a core to create engineered hardwood flooring.

Volatile Organic Compounds (VOCs)

Refers to carbon-based chemicals that easily evaporate at room temperature and can trigger allergic reactions, asthma, and upper respiratory infections. Thousands of different VOCs are produced and used in our daily lives. Some common examples in building materials include: carpets and adhesives; composite wood products; paints; sealing caulks; solvents; upholstery fabrics; varnishes; and vinyl floors.
Tip: Always wear a fume/vapor mask when using or applying finish to your floor.

Warping

WarpingAny distortion of a piece of wood from its true plane. Types include: bow (a warp along the length of the face of the wood); crook (a warp along the length of the edge of the wood); kink (a localized crook, often due to a knot); cup (a warp across the width of the face, in which the edges are higher or lower than the center of the wood); and twist (a distortion in which the two ends do not lie on the same plane).

Wear Layer

The portion of a floor covering that contains or protects the pattern effect.

White Wash

A cost-effective wood finish that cures over time to provide a chalky, worn look.

Wide Plank

Board widths that are 5” or greater.

Width

The width of the individual wood boards that make up the floor. “Strips” are narrow boards measuring less than 3 inches wide. “Planks” are wider boards, measuring 3 inches wide or more.

Wire-Brushed

A distressing technique to give wood boards a time-worn look.

Working Pressure

The pneumatic pressure range specified in pounds per square inch (PSI) to optimally run an air tool.

Wood stain (stain)

A type of paint that is very “thin,” or low in viscosity and formulated so pigment penetrates the surface rather than remaining in a film on top of the surface.

Hardwood Flooring Reference Tool & Definitions

Hardwood Flooring Reference Tool & Definitions

by | Jan 21, 2020 | 0 Comments

Quick reference guide for hardwood tools & definitionsAbove Grade A suspended floor located above ground level, with a minimum of 18 inches of ventilated air space below. Normally above a basement, but a suspended floor may also be above a crawl space. Abrasion...

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Why Flooring Professionals Must Always Test For Excessive Moisture And Alkalinity

Why Flooring Professionals Must Always Test For Excessive Moisture And Alkalinity

Why Flooring Professionals Must Always Test For Excessive Moisture And Alkalinity

Moisture can cause a wide range of hardwood flooring problems

It’s no mystery. The leading cause of flooring failures is moisture.

Industry experts say approximately 85% of all installation failures result from moisture problems. In fact, moisture accounts for more than $1 billion in damages annually.

Moisture can cause a wide range of hardwood flooring problems that may occur soon after installation or, in some cases, months or even years down the road. These problems include cupping, buckling, blistering, crazing, adhesive failure or delamination, warping, scaling, pop-outs, efflorescence, discoloration, gaps or cracks, swollen joints, and even mold or mildew growth.

The reason moisture is the root cause of many flooring failures is simple. Concrete slabs, wood subfloors, and the wood flooring placed above a slab or subfloor are by their very nature porous. So they easily absorb and release moisture.

While it’s critical to ensure hardwood flooring reaches its equilibrium moisture content (EMC) with the air (that is, attain an optimum moisture level before installation), it’s equally – and perhaps even more – important to accurately measure the moisture content of the concrete. Why? Because moisture passing from or through concrete has become the number one cause of floor covering failures in this country.

For that reason, most U.S. producers of floor coverings, adhesives and resinous coatings require accurate moisture testing of both concrete and wood in order to avoid flooring failures.

It’s important then that wood flooring professionals have an understanding for the need of both concrete and wood floor moisture testing. They should also know the difference between the two recognized concrete test methods and the two types of hardwood moisture meters.

Let’s look at how moisture affects concrete before moving on to moisture’s effect on wood flooring.
Concrete Trowel

Concrete and Moisture

Concrete is porous material. The more porous it is, the greater the potential for moisture vapor to move at a volume harmful to the floor covering. Concrete slabs with a high moisture emission rate and/or too high a pH level will always be detrimental to a successful flooring installation.

Excess moisture in concrete can occur for various reasons:

  • There may be too much water in the concrete mix
  • Too little curing or drying time
  • Rainfall from incomplete roofing systems
  • Lack of HVAC climate control
  • Poor landscaping that fails to drain water away from building foundations.
  • Buffing the concrete smooth to iron out imperfections that may “telescope” into the floor covering. This practice hinders drying time because it seals the concrete’s pores.

High Alkalinity and Time

A related problem to excess moisture – too much alkali. High alkalinity destroys the bond between the adhesive and floor covering. High alkalinity occurs when too much moisture moves through the slab.

Alkalinity is a natural constituent of all concrete. The good: the internal alkaline state of concrete prevents reinforcing steel from rusting. The bad: when the surface of a concrete slab has an alkalinity above 9 on a pH scale (usually 10 and above), adhesive and bonding systems can be compromised.

To ensure concrete is at the proper state of alkalinity, testing with pH paper or a pH meter must be performed. Moisture causes damage, but moisture at a high pH is disastrous.

Still another problem is time. Many building contractors work on a fast-track construction schedule. As a result, concrete is not given enough time to naturally dry before installation of floor covering materials and coatings.

Making matters worse, is the use of curing compounds which inhibit or prevent concrete from drying . . . and the use of floor covering adhesives and coatings which are more sensitive to moisture and alkali assault than previous materials.

Keep in mind, flooring installers are attempting to adhere floor covering materials using water based adhesive systems to a water-based agglomerate called concrete. Excessive moisture emission from concrete that has not sufficiently dried will almost always interfere with the ability of an adhesive to bond or cure properly.
Concrete Slab

Concrete versus Cement

To avoid confusion, it’s important to distinguish “cement” from “concrete.” Though they’re often considered the same thing, they are not. Cement powder is the material, typically grey, combined with sand, water, gravel, or crushed stone to make concrete. Concrete, therefore, is a combination of cement and aggregate materials.

There are two types of cement: hydraulic cement and non-hydraulic cement.

Hydraulic cement (e.g., Portland cement) hardens by reacting with water to form a water-resistant product. It sets extremely fast and hardens even under water. It’s used to stop water and leaks in concrete and masonry structures, and is used widely where structures are submerged in water.

Non-hydraulic cement (e.g., lime and plaster of Paris) cannot harden while in contact with water. It must be kept dry to gain strength and hold the structure. When used in mortars, those mortars can set only by drying out, and therefore gain strength very slowly.

Both types of cement can be combined with fly ash, lime, silica fume, blast furnace slag, and other additives to give a variety of strengths and colors to the various cement blends.
Leveling Concrete

Curing versus Drying

When cement is mixed with sand, water, and aggregate, a chemical reaction occurs binding the materials together to form concrete. It takes roughly four weeks for this chemical process to be complete in a 4-inch slab. This process is called “curing.”

It’s a common misconception to say that concrete dries when actually it’s curing. Curing is not the same thing as drying.

Curing requires adequate moisture, temperature, and time to allow the concrete to achieve its desired properties. When a slab is considered “cured,” it still holds an appreciable amount (about two-thirds) of the moisture from the original concrete mixture. Obviously, this is way too much to install a flooring product over, so the concrete needs additional time to dry thoroughly.

A concrete slab typically cures in 28 days. Drying time continues after curing – about one month for each inch of slab thickness.

So even after curing, drying continues. Moisture moves through the slab to the surface where it then evaporates. It will, however, be replaced by more moisture drawn up through the entire slab.

Thus, it’s important to keep in mind that even when a slab may be considered cured or even “dry,” it may not be fully dry enough. Environmental conditions like temperature and air humidity can affect the drying process.

It’s imperative then that accurate moisture testing be done to ensure the slab is dry enough to apply a floor covering.

Under certain conditions, engineered wood flooring may be able to be installed directly over concrete or in below grade applications. This is something that cannot typically be done with solid wood floors. However, vapor transmission testing must be done first to determine if the level of concrete slab vapor emissions or hydrostatic pressure is acceptable. If not, excessive moisture in a basement slab or concrete slab can ruin an engineered wood flooring installation.
Wood Flooring Over Concrete

Floor Covering Problems

When a floor covering shows signs of moisture-related failures, the problem is likely due to one of the following;

  • The concrete slab has a higher moisture emission rate than the floor covering can tolerate.
  • The concrete was not cured or dried sufficiently before installation of the floor covering.
  • No moisture testing was performed or it wasn’t done correctly.
  • The moisture testing didn’t show future concrete slab behavior.
  • Alkalinity is too high in the concrete due to a high moisture emission rate.

Alkalinity is measured by pH from 1-14. Ideally, concrete should have a pH of 7-9 before installing a floor covering; otherwise, the high alkalinity (high pH) combined with moisture will destroy flooring adhesive bonds.

Freshly mixed concrete is highly caustic and extremely alkaline – well above 10. This condition may compromise adhesives and flooring materials. As concrete ages and reacts with carbon dioxide in the air (part of the curing process), the alkalinity (or pH level) of its surface gradually decreases.

Before flooring is installed, the pH level of the concrete surface should be between 7-9. However, flooring installers should check the pH level recommended by the adhesive manufacturer as well as other manufacturers’ products that might be used on the subfloor, such as moisture barriers, epoxy coatings, and leveling compounds.

ASTM states that a pH test should be performed along with every moisture test. Many flooring manufacturers require pH testing be conducted before flooring is installed.

Measuring pH

There are a couple of ways to measure pH. One way is to use paper test strips which change color according to the alkalinity of the concrete. But a more accurate way is to use a pH meter, which gives a numerical reading on a digital display.

To test pH, one must:

  1. Sand a small section of the concrete surface with 200 grit sandpaper. This removes any impurities from the surface that might affect the test results.
  2. Remove the dust with a vacuum cleaner.
  3. If the surface doesn’t pass the water drop test, that is, the surface is still not porous after sanding, the non-porous material will have to be removed using a hand grinder. If the water beads on the surface, it will not give an accurate pH reading because only the water drop itself will be tested
  4. Put several drops of distilled or deionized water on the prepared surface. Use the test strip or meter to see if the water has a pH reading of 7 before using it.
  5. Leave the drops on for 60 seconds and then place the test strip or meter in the water. Wait for the period of time specified by the manufacturer.
  6. If test strips are used, compare the color of the strip to the pH color chart. Or, if using a pH meter, read the meter’s digital display.

Proper and Accurate Concrete Moisture Testing

Testing concrete for moisture must not be done haphazardly. In order to attain accurate results, proper testing procedures must be followed to avoid costly problems later.

For instance, testing the slab’s surface only once is inadequate when trying to make an intelligent decision about installing flooring. Since a slab may dry unevenly, proper testing should include a number of different spots on the slab as well as below the slab’s surface.

Also, a combination of tests is better than a single test. The American Society for Testing and Materials (ASTM) has written standards for testing moisture content using two different test methods: Calcium Chloride testing (ASTM F1869) and In-Situ Relative Humidity testing (ASTM F2170).

There is a growing number of floor covering manufacturers suggesting or requiring both of these tests to determine dryness and suitability for installing their products.

Calcium Chloride Test ASTM F-1869

The calcium chloride test, long considered the standard for testing concrete moisture vapor emissions, has been in use since the 1940s. This test produces a moisture vapor emissions rate (MVER), which is a reading of how much moisture content is released from 1000 square feet of concrete slab over a 24-hour period. The results are expressed as pounds of moisture.

As a desiccant, calcium chloride absorbs moisture from the air. Typically, a small plastic dish of anhydrous calcium crystals is weighed on a gram scale before placement to determine moisture content. The weight, date and time the test was started is recorded. The dish of crystals is placed on the concrete for 60 to 72 hours, covered, and sealed with plastic tape to the concrete.

During this time, the only source of moisture absorbed by the anhydrous crystals is what can evaporate out of the covered concrete surface area. At the end of the test, the cover is removed and the lid is placed back on the dish and sealed. Again the dish is weighed on the gram scale and the date and time are marked. The change in weight is multiplied by a constant and divided by hours to provide an estimated rate of evaporation in pounds.

For example, water weighs 8.3 pounds per gallon. “Pounds” is the equivalent weight of water that evaporates out of a 1,000 sq. ft. surface area during 24 hours. If the test reports 8.3 pounds emission, then one-gallon of water is leaving a 1,000 sq. ft. surface area in 24 hours. When flooring is to be installed, an allowable amount of moisture emission, as expressed by the calcium chloride test, is 3.0 pounds per 1000 sq. ft. per 24 hours.

For new construction, ASTM requires 3 kits for the first 1,000 sq. ft. and at least 1 kit for each additional 1,000 sq. ft. The temperature of the surface should be between 50-70º F. The internal conditions in the room should be 40-60% humidity and 65-85º F.

Shortcomings of the Calcium Chloride Test

The Calcium Chloride test, however, is not foolproof. It has a number of shortcomings, and as a result, some floor manufacturers no longer recognize Calcium Chloride test results for determining concrete dryness.

Here are some of the cons for the Calcium Chloride test:

  • Too many tests are being set without floor preparation as required by ASTM F1869. Surface contaminants and residue from paint, adhesive curing or parting compounds can reduce vapor emission at the test site and produce inaccurate test results. In short, the concrete pores must be open.
  • It requires a specified waiting period and the correct number of tests performed based on square footage. This test measures vapor emissions at the time of testing, which can change as the building environment changes.
  • It measures moisture vapor emissions only from the top ¼” to ½” of the slab, so it doesn’t indicate moisture deep in the slab. If ambient environmental conditions immediately preceding testing have been extremely wet or dry, the concrete surface may be affected and test results may be skewed.
  • The subject building must be acclimated at or near the temperature and relative humidity levels anticipated during occupancy or use. This is often a difficult requirement to meet on a new construction project. Significant variance between the test environment and intended use environment should cause test data to be questioned.
  • The most current revision of ASTM F1869 specifically excludes Calcium Chloride tests from use on lightweight aggregate concrete.
  • “Homemade” Calcium Chloride test kits are being used and in some cases by very reputable labs. Some of these kits do not meet the apparatus requirements of ASTM F-1869-09 and are delivering questionable results.

In-Situ Relative Humidity Testing ASTM F-2170

ASTM Committee F.06 on Resilient Flooring has developed and published a standard for In-Situ Testing of Concrete Relative Humidity. This test method has been used extensively in Europe. It enables flooring professionals to check the moisture level within a concrete slab through relative humidity (RH) testing using in situ probes.

After side-by-side testing with Calcium Chloride kits, there is evidence that the In-Situ Relative Humidity (RH) data is more useful and meaningful than Calcium Chloride test results. In other words, RH probes are less sensitive to changes in ambient air humidity and temperature above the slab than calcium chloride testing.

In that regard, In-Situ RH testing provides more meaningful data under conditions that may not be acceptable for Calcium Chloride testing.  As a result, some industry experts believe this test is a more accurate way of predicting what will happen to the slab in the future.

Probes Are Inserted Into The Slab

rapid rh at 40%

This test involves drilling holes at a diameter of 5/8” to a depth equal to 40% of the slab thickness. The hole is then lined with a plastic sleeve and the sleeve is capped. The test site must be permitted to acclimate for 24 hours before reading relative humidity levels.

After or during acclimation or equilibrium, a probe is placed in the sleeve that permits readings to be obtained from the bottom of the hole, thus offering a method to measure moisture content inside of the concrete slab reported as a relative humidity level.

It is critically important that probe sensor temperature is at equilibrium with concrete slab temperature. Testing should take place in an acclimated building and at the same test placement density as noted above.

This concrete moisture test method is less affected by conditions occurring at the concrete surface, which may negatively influence Calcium Chloride test results. Consequently, this test provides the best picture of the moisture conditions the adhesive and finished flooring product would encounter if they were installed at that time.

In-situ RH testing performed at multiple depths permit a testing agency to develop a profile of moisture conditions through the thickness of a concrete slab. This information permits the user to make a more informed decision regarding the installation of floor coverings or the need to consider other alternatives.

The water content in concrete migrates from the bottom of a slab to the surface, where it evaporates according to changes in RH. It’s imperative, therefore, that the concrete’s internal moisture be allowed to dry to the proper level in order to avoid problems with adhesives and flooring products after installation.

Unfortunately, many builders mistakenly believe that surface moisture content levels reflect those of the whole slab. They neglect internal slab moisture levels. A concrete moisture meter will tell them relative moisture on the surface, but only relative humidity (RH) testing gives them an internal, and more accurate, assessment.

Although relative humidity test probes are not sold as reusable (some are, but require re-calibration for each test site), the sensors remain intact. They can be re-used over and over.
Finishing Concrete

RH Test versus Calcium Chloride Test

In terms of cost-efficiency, relative humidity testing is better than anhydrous calcium chloride testing. Calcium Chloride test materials must be discarded after each test procedure is complete. This means new kit test costs. Relative humidity testing, however, produces multiple sites throughout a concrete slab which can be assessed repeatedly.

One advantage of the RH test is that it’s less impacted by ambient temperature and relative humidity conditions than calcium chloride type tests. Thus, conditions that are not acceptable for calcium chloride testing may not generate meaningful data.

Wagner Meters, with its state-of-the-art Rapid RH® system for RH testing, saves on total material costs and preparatory work for flooring installers. The Rapid RH in-situ test method saves more than 150 hours of installation time (based on industry estimates for 13 slab tests).

Here is a breakdown of time (cost) savings:

  • Preparation: 130 minutes
  • Site protection: 120 minutes
  • Test processing: 125 minutes
  • Clean-up: 13 minutes

Smart Sensors equilibrate to produce meaningful RH data within one hour of installation, though the ASTM standard requires a 24-hour reading before making an installation decision. The Wagner Meters’ Smart Sensors continue to digitally read moisture content levels at the point of installation. This enables builders to repeat tests at each test location on site to capture an ongoing RH assessment. Project managers for large commercial construction projects find this to be especially valuable.

The Rapid RH offers multiple benefits. Users realize built-in cost savings since the system offers the lowest cost per test than other In-Situ RH test systems, plus lower time and labor costs. It’s also easy to use and 10 times faster than other RH tests.

Once installed, the Smart Sensor and Easy Reader work together to provide accurate, instant readings at a touch. And, the new, award-winning Rapid RH Datamaster helps streamline data records and ASTM-compliant reports.

Wagner Meters’ Rapid RH system offers flooring and building professionals the concrete moisture data they need to meet ASTM F2170 standards. And each disposable smart sensor comes with an NIST traceable factory calibration certificate, providing reliable accuracy and completely eliminating the need for periodic calibrations typically required by other sensing technologies.

In addition to meeting industry standards, the Rapid RH system also has received impressive industry accolades and reviews.

Other Common Tests

There are other tests that can be used to determine moisture and alkalinity levels, but they are not quantitative like the calcium chloride or in-situ relative humidity tests. Although they may indicate the presence of moisture or alkalinity, many flooring manufacturers insist that one or both of the ASTM endorsed tests be conducted to satisfy their requirements.

These other tests include:

Polyfilm Test
In this test, several pieces of plastic film, 18” – 24” square, are placed at key points on the cement, then sealed with silver duct tape on all four sides. The plastic film is removed after 24 hours (72 hours is better) and inspected for signs of condensation. Use of a heat source, such as a 40 to 60 watt light bulb placed 18” above the plastic “accelerates” this test.

If beads of water are found on the subfloor or the concrete appears darker, this serves as notice that further testing is necessary. Installation can proceed if there’s no indication of moisture.

Phenolphthalein Test
This test requires drilling dime-sized 1/4-inch deep holes in various areas of the slab, especially around the walls, and then applying in each hole two drops of a 3 percent phenolphthalein solution in water-free ethyl alcohol. If there’s no color change in the solution, this means moisture and alkalinity are not at levels to affect the installation.

Should the phenolphthalein turn pink or dark red within five minutes and the pH is 9.0 or higher, further testing must be done with a more precise method.

Wood Subfloor

Improper moisture conditions in a wooden subfloor can also lead to moisture-related problems associated with a concrete slab. Flooring specialists can test the moisture content of a wood subfloor using the pinless wood moisture meter. Similar to the hardwood floor, the wood subfloor must have an acceptable moisture content to avoid flooring failures over time.

Flooring specialists should test several areas of a wood subfloor to be certain conditions are acceptable for the final flooring installation. A good rule of thumb is that the subfloor moisture content should be within 3-4 percentage points of the flooring to be installed before proceeding.

Wood Flooring

Regardless of whether hardwood or engineered flooring is to be installed, all material should be checked with an accurate wood moisture meter. This involves opening and testing several bundles to ensure the wood flooring is the same MC throughout, and is compatible with the subfloor which the flooring will cover when installed.

As with the wood subfloor, pin-style and pinless meters can give an indication of the MC to ensure a professional and long-lasting flooring installation.

The pinless meters haves some unique advantages over the pin-style meters. Since they don’t use pins, they won’t damage the wood flooring with unsightly pin holes. That means no filing or sanding on the final floor. They also enable installers to measure entire bundles in a matter of seconds.

The Wagner Meters Orion line are pinless floor moisture meters which offers flooring professionals a versatile range of options for measuring and monitoring wood moisture content. Considered one of the world’s most accurate hardwood moisture meters based on third-party and university tests, it comes with dual-depth reading options and Wagner’s signature IntelliSense™ technology for accuracy that is virtually unaffected by surface moisture.

The Orion floor moisture meter also features a specific gravity (SG) range that covers most wood species including dense, tropical species. It provides a moisture measuring range of 5% to 30%. And, it displays moisture readings to one-tenth of a percent (0.1%) resolution on an easy-to-read digital display.

Moisture levels in the average household are considered to be between 6-9% and wood flooring is generally dried to this level. But regional and seasonal variations mean that even wood flooring manufactured from properly-dried lumber will need an acclimation in the installation environment to prevent extreme changes in the finished floor. For instance, even a change as small as 1/32” per 2” board multiplied across an eight-foot room equals 1 ½” of gapping or swelling.

In Closing . . .

All flooring professionals need to be proactive when it comes to proper installation of wood flooring. Accurate moisture testing is their best defense against moisture-related flooring failures that can lead to wasted time and financial loss . . . and even a tarnished reputation.

Hopefully, this article has provided a basic understanding of why moisture testing is extremely important, and why it applies not only to the wood flooring, but also the concrete slab and wood subfloor.

Interested in moisture testing?

Find out which moisture meter is best for you!
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Common Hardwood Flooring Problems: Prevention and Cures for Installation and Finishing Issues

Common Hardwood Flooring Problems: Prevention and Cures for Installation and Finishing Issues

Common Hardwood Flooring Problems

Prevention and Cures for Installation and Finishing Issues

Alligatoring

The finish pulls away from itself, causing ridges in the finish similar to an alligator’s skin. This condition can occur in both water-based and oil-modified finishes.

Prevention: Alligatoring can be prevented by avoiding the following finish application mistakes:

  • Poor wetting of the finish.
  • Contamination of the finish.
  • Finish application under cold temperatures.
  • Application of a new finish coat before the previous coat has dried.
  • Application of a heavier finish coat than is recommended.
  • Use of thinners that cause the finish to dry too quickly.
  • Application of oil-modified finish over waterborne finish or vice versa when the finish is not completely cured.

Cure: Screen and recoat after the finish has dried sufficiently.

Applicator Streaks

After the floor dries, marks still are visible from the path of the applicator. It usually is associated more with water-based finishes than other types of finishes, although it may affect other types, as well.

Prevention: Avoid the following mistakes when applying finish:

  • Using an applicator that has hardened spots.
  • Improper spread rate—too much or too little finish is applied.
  • The finish is not applied evenly.
  • Excessive air movement and abnormally high temperatures causing the finish to dry too quickly, resulting in a wet edge of finish being pulled over one already dried.
  • Applying a satin or semi-gloss finish that has not been stirred properly.
  • Applying finish in directly sunlit areas or other areas that are hot.

Cure: Screen and recoat after the finish has dried sufficiently.

Bleed Back

Occurs when excess stain seeps up from the grain or from the spaces between boards.

Prevention: Avoid the following:

  • Excessive stain application.
  • High-viscosity or highly pigmented stain.
  • Excessive heat during application.
  • Knots or areas that contain higher amounts of sap.

Cure: Wipe off the excess stain or burnish/buff the floor with a white pad to remove the excess and even out the stain color. Then, let the stain dry thoroughly before applying another coat. If finish already has been applied over bleed-back, a complete re-sand is required. Trowel filling a floor can help prevent bleed back. Cover windows during application to prevent hot spots on the floor.

Bubbles

Dried bubbles are visible on the surface of the finish.

Prevention: Avoid the following:

  • Soap or some other contaminant was not removed before coating.
  • Applying hot oil-modified finish onto a cold floor.
  • Applying finish to a hot floor.
  • Overworking finish during application.
  • Air movement across the floor that dries bubbles into place before they can flow out.
  • Floor not screened or sufficiently cleaned between coats of finish.

Cure: Problems in the topmost finish coat can be screened and recoated, while cases of delamination require complete sanding and refinishing. Cover windows during application to prevent hot spots on the floor.

Buckling

The wood flooring becomes separated from the subfloor, usually is accompanied by cupping and swelling. Buckling is caused by: excessive moisture at the job site; a house left vacant with no ventilation (see Greenhouse Effect); grade conditions; pipe leaks; a wet slab.
Extra Resource: Article: Learn The Warning Signs

Prevention: Excessive moisture is usually the main cause of buckling. Be aware of these improper installation techniques, which can aggravate the problem:

  • For nail-down products: inadequate nailing, incorrect fasteners, and incorrect subfloor construction.
  • For glue-down products, incorrect adhesive, insufficient adhesive, the wrong trowel, inadequate adhesive transfer (due to over-flashing or not rolling the floor), subfloor separation or subfloor contamination.
  • Inadequate expansion space left by the installer.

Cure: Fix the excessive-moisture condition and allow the floor to dry to normal levels. Spot repair/replacement, reinstallation, re-nailing and refinishing are also options. In most cases where the flooring has loosened from the subfloor throughout the installation, reinstallation or replacement may be necessary.

Chatter or Wave Marks

Chatter marks are consistent sanding imperfections across the grain of the wood varying from 1⁄4 inch to 1 inch apart. Wave marks are two or more “upsets” occurring along the direction of travel of a sander. They generally are 1 to 3 inches from peak to peak.
Extra Resource: Article on recommended flooring tools

Prevention: Most chatter marks are caused by the sanding drum. Before you begin, check the drum for balance and round, hard spots, incorrect paper installation or compressed rubber. Other problems include:

  • Poor splice/seams on the abrasive belt, drive belts and fan belts
  • Running the machine in the wrong direction (for belt sanders, right to left; for drum machines,left to right)
  • Worn pulleys
  • Bad bearings in the fan housing
  • Loose flooring

Most wave marks are caused by imperfections already present on the floor that are transferred through the wheels of the machine to the sanding job. Check for:

  • Wheels on the big machine that are out of round.
  • Improper electrical hookup (voltage too high or low).
  • Undulation of the floor from inadequate joist design.

Cure: First, determine and correct any problems with the sanding machine. Then, use a hard plate, paper disc or multi-disc sander (A sanding screen only highlights the chatter and causes the floor to dish out). Use a disc sander and hard plate while working right to left, traveling down and back in the same path and working the disc sander at slight angles for the best cut of the unit. Repeat the same procedure, overlapping the last cut one-half the size of the first disc.

Another technique is to do a light sanding with the machine at a 7-degree angle, then go over the floor again, this time straight. If using a multi-disc sander, walk slowly with the grain from side to side, always overlapping the unit as you move from right to left. This blends in the floor and prevents deep scratches. If joist design or loose flooring is the problem, the structural flaws must be corrected before the floor is re-sanded and refinished.

Chipping

Dried finish separates from the surface in the form of flakes or chips.

Prevention: Avoid the following:

  • Applying a less elastic finish on top of a more elastic one.
  • Improper adhesion between coats.
  • Spot contamination.

Cure: Screen and recoat. More than one coat may be needed, or problem areas may be spot-coated before screening and recoating the entire floor.

Cloudy Finish

The finish appears cloudy or milky.

Prevention: Do not applying finish over a coat that isn’t dry.

Cure: Screen and recoat, being sure to increase the dry time between coats. Check with a damp rag before reapplication of finish to make sure the cloudiness has disappeared—if the finish appears clear when it is dampened, the problem probably has been eliminated, and the floor is ready to be coated over.

Cratering

Often mistaken for bubbles, this problem resembles craters on the moon.

Prevention: Avoid the following:

  • Contamination of the floor or finish.
  • Application of finish over previous coats that are not dry or have not gassed off.

Cure: Sand the crater out by hand-sanding, and then screen, pad and recoat. Oftentimes, hand-sanding out the craters will leave an unevenness in the floor. To eliminate low spots, spot finishing the areas may be necessary before the entire floor is recoated. If the problem is severe enough, the floor may need to be re-sanded.

As a general rule, trowel-filling the floor may help prevent problems due to contaminants in the cracks between boards.

Crowning

The center of the flooring pieces appear to be higher than the edges.
Extra Resource: Cupping and Crowning: Spotting Trouble

Prevention: While it’s possible that excessive moisture could cause crowning, it is more likely that the floor cupped and then was sanded flat before it could dry and flatten on its own. When the floorboards did dry to a normal condition, their edges had been removed, making them lower than the center of the board. Gaps are generally formed as the flooring dries.

Cure: First, determine if the moisture content is normal and if all of the crowning from the original cupped condition has occurred. After the floor has stabilized, re-sand and finish.

Cupping

Occurs across the width of the individual pieces of flooring. The edges are high, and the center is lower.
Extra Resource: Cupping and Crowning: Spotting Trouble

Prevention: Cupping is usually caused by an excessive moisture differential within individual pieces of flooring and excessive moisture on the underside of the flooring. More subtle cupping can be caused by lack of proper acclimation (this is generally permanent cupping). Check for potential sources of excessive moisture, including:

  • Building leaks
  • Poor drainage
  • Plumbing leaks or overflows
  • Leaks from dishwashers or refrigerator ice making units
  • Wet or damp basements/crawlspaces
  • Concrete subfloors that have not cured
  • Plywood subfloors with excessive moisture
  • Poor or no ventilation
  • HVAC system not operating.

Flooring may also cup when a wood floor experiences conditions that cause rapid drying on the surface. This condition occurs with gaps as the flooring shrinks.

Cure: Never attempt to repair a cupped floor until all sources of excessive moisture have been located and eliminated. This can be verified only with a moisture meter that takes readings of the underlying subfloor. As long as the wood is not permanently deformed or damaged, the flooring will return to its original shape and size when the excessive moisture is removed. This may take weeks, months, or even an entire heating season.

Attempting to sand a cupped floor while it is still too wet may cause subsequent crowning when the floor dries. Flooring that does not return to its original shape, even after completing an entire heating season, probably is permanently deformed (Taking moisture readings at different levels in the wood flooring also can help determine this—if there is a gradient of 1 percent or more between the top and bottom of the boards, they probably are not done drying). If the boards are permanently deformed, the cupped edges may be sanded off. For floors that have cupped due to drying, relative humidity should be increased. Relative humidity below 20 percent is considered very dry for wood flooring, and it is suggested that humidification be provided under such conditions.

Dents

Crushed spots in the wood.

Prevention: Institute good floor maintenance procedures, such as removing high heels and using floor protectors.

Cure: If wood fibers are not broken, attempt to draw fibers back up with an electric iron over a dampened cloth. If fibers are broken, remove and repair the damaged boards. The entire floor may need to be re-sanded and refinished.

Discoloration

The floor changes color over time. Some areas may darken more than others.

Prevention: Understand that changes in a floor’s coloring over time is natural and to be expected. Despite the pervasive myth that an oil-modified finish recoated with waterborne finish will stop ambering, ambering of oil-modified finishes cannot be prevented. Wood lying in direct sunlight will also change color over time, and wood also changes color through oxidation. Shading the floor can minimize lightening. Customers should be informed that certain species, particularly cherry and many exotics, will change color greatly as they age.

Cure: If marks are left on the floor by area rugs or furniture, moving them around can equalize the change in color.

Dish Out

Areas on the wood floor where softer parts of the wood appear to have been sanded more than other areas. Occurs between areas of annual rings or between mixed species of varying hardness together on a floor, such as in feature strips, borders and medallions.

Prevention: Ensure you use the proper angles while sanding.

Cure: Re-sand the floor using a slight angle with the big machine. A hard plate or multi-disc sander may be needed on softer woods.

Excessive/Early Finish Wear

The appearance of too much wear on a relatively new finish.

Prevention: Most excessive or early finish wear is due to improper maintenance procedures. Avoid the following:

  • Failure to fully remove grit from the floor’s surface.
  • Using water to clean the floor, or using strong cleaners on the floor.
  • Pet nails and chair legs

Mistakes during finish installation can also cause excessive or early finish wear. Avoid:

  • Not enough finish applied to the floor initially.
  • Applying finish over coats that have not had enough time to gas-off and dry.
  • Improper sanding procedures—when the floor is left too rough, finish accumulates in the bottoms of the grooves in the floor, leaving little coverage on the “peaks,” where the finish then wears through. This may give the appearance of ridges in the flooring.

Cure: Follow proper maintenance procedures, including regular dust-mopping with an approved wood-floor cleaner, use of throw rugs and use of floor protectors. If caused by improper sanding, re-sand and recoat.

Fisheyes/Crawling

A circular, cloudy haze with a clear center that can measure up to about 1 inch in diameter.

Prevention: Avoid contaminating the surface—the new coat “crawls” away from the wet or contaminated areas, giving the appearance of fisheyes when the finish sets. Also, if the finish container has sat undisturbed for some time and has not been properly agitated, a disproportionate amount of flow and leveling agents may be put on the floor, causing a fish-eyed appearance.

Cure: Screen and recoat.

Flooded Floors

Standing water on the wood floor.
Extra Resource: Disaster Relief and Flooding

Prevention: Common sense measures prevail, although flooding, like other natural disasters, can often be an event beyond your control.

Cure: Remove the water and dry the floor as quickly as possible. Elevate the temperature, dehumidify and increase airflow using fans. In basement houses, dry from below. In crawl space homes, use exhaust fans. If the flooding was of a long duration on a surface-finished floor, rough sanding to remove the finish will accelerate drying. Lightly sand at a slight angle of about 7 degrees. Or, use a buffer or orbital sander with a 120-grit screen backed by a soft pad. (Sanding this way should not remove the edges, which could cause crowning later). Do not sand down to bare wood, but rather remove the majority of the finish.

Do not repair the floor until moisture meter readings on the top and bottom of the boards and subfloor are at normal levels. When flooring is stabilized, determine the damage. If the flooring has loosened from the subfloor, repair the necessary areas or the entire floor. If it is cupped, sand it flat. If the floor is flat, fill if necessary and screen and recoat. If the subfloor is plywood over concrete, it is unlikely that the plywood and concrete subfloor will dry out in a reasonable time. Full removal to concrete usually is best to allow the slab to dry.

In cases where you have determined that the flooring system has not returned to normal levels, do not succumb to pressure from involved parties for a quick fix. If you must proceed, have a full release signed due to the risk of more moisture problems.

Gaps, Normal

Gaps between strips/planks that appear between individual boards and open and close with changes in humidity.
Extra Resource: Article on Wood Flooring Movement

Prevention: Most normal gaps are caused by seasonal fluctuations in relative humidity—the floor expands with high humidity and contracts during periods of low humidity. This type of expansion and contraction is considered to be normal and expected for solid wood floors. In solid 21⁄4-inch floors, gaps may be the thickness of a dime (1⁄32 inch) or wider. Wider boards have even wider gaps.

If normal gapping is a concern to you, chose light –colored floors, which show gaps less than dark floors, and beveled floors, in which gapping as not as obvious as in square-edged floors.

Cure: Normal gaps can be minimized by using the HVAC system to control fluctuations in humidity in the building. The use of humidifiers or dehumidifiers can narrow the overall fluctuation range.

Gaps, Abnormal

Gaps in the floor that remain with seasonal change. If some boards appear glued together by the surface finish, see “Sidebonding/Panelization.”
Extra Resource: Article on Wood Flooring Movement

Prevention: Check for and be aware of the the following potential causes before and during hardwood flooring installation:

  • Edge crush from prior exposure to extreme moisture (especially for solid, flat-grained flooring).
  • Hot spots in the subfloor, such as poorly insulated heating ducts, hot water plumbing lines, radiant heating systems, register openings and refrigerator motors.
  • Debris between boards during installation.
  • Improper nailing/nail position.
  • Flooring installed with an excessively high moisture content or over a subfloor with excessive moisture.
  • Flooring not installed tightly together to begin with.
  • Foundation settlement.
  • Improper subfloor materials that will not hold nails.
  • For glue-down floors, early foot traffic, incorrect adhesive, the wrong amount of adhesive transferred or used, the wrong amount of flash time for the adhesive, or not using a roller when recommended.

Cure: Eliminate the cause(s), then restore normal humidity levels. After the floor has stabilized, use filler in gaps that are small enough to be filled (typically up to 3⁄32 inch) and recoat the floor. For larger gaps, use a sliver or “Dutchman” to fill in the gap. Pulling up the entire floor and reinstalling may be necessary.

Grade Problems

Dissatisfaction with the floor due to the appearance of knots, grain pattern, color variation, etc.

Prevention: Manage customer expectations during the entire process so there is a clear understanding of what the finished product will look like. This may include educating customers about natural wood variations and distinction this lends to hardwood floors.

Grade problems can also occur through ordering mistakes by the supplier, distributor or installer; poor grading at the mill; or an improperly labeled product.

Cure: Replacing the offensive boards may be necessary.

Greenhouse Effect

Floors that shrink or swell due to an abnormal level of humidity in a vacant house.
Extra Resource: Moisture Related Problems

Prevention: The greenhouse effect happens when houses are closed up with no airflow; when sunlight through windows generates heat; and when condensation and humidity build. Avoid these potential hazards by carefully regulating moisture in the home, even when it is closed up for an extended period of time.

Cure: After the environment returns to normal, follow cures discussed for cupped floors or shrinkage gaps.

Insects

If the surface of the flooring is sagging, it is likely that termites have created eating corridors beneath the surface. The bugs are white or cream colored. If fresh holes about 1⁄16-inch wide are found, powderpost beetles, or lyctid beetles, probably are the cause. Positive identification of the infestation is necessary and should be performed by an entomologist.

Prevention: Most wood damage from insects and fungal rot can be prevented with relatively low toxicity insecticides and/or pest-targeted baits. Furthermore, lmost all wood flooring in North America is kiln-dried, and proper kiln-drying should kill any insect infestations. Check all surroundings for infested wood molding and furniture (especially bamboo, mesquite and ash).

Cure: For termites, a professional exterminator should eliminate the bugs. Then, structural damage should be repaired. Damaged floorboards should be pulled and replaced. Termite infestation is not related to wood floors, and full cost should be covered by the owner. For powderpost beetles, determine the extent of damage. If infestation is heavy, handle it the same as the termite extermination above. If it is occasional, especially in new floors, treat the individual openings immediately with insecticide injected by a syringe into the holes. Or, use aerosol insect spray through a straw in the holes. Have the owner watch for evidence of new holes (with little dust piles) and treat again. After two to three months, the holes may be filled.

Iridescent Finish

The finish dries with a metallic, colored cast to it.

Prevention: Adequately ventilate during the drying of a coat of finish, which prevents solvent saturation in the air that then settles on the floor and is coated over.

Cure: Screen and recoat using proper ventilation.

Orange Peel

The surface of the finish has a texture that resembles an orange peel.

Prevention: Avoid the following:

  • Rolling a finish that is not designed to be rolled on, causing it to dry too quickly. When that happens, the texture is “frozen” into place before the finish has a chance to flow out and level.
  • Using a finish or substrate that is too cold.
  • Use of an improper applicator that causes small bubbles to form in the finish. The bubbles then pop, leaving small dimples in the finish.

Cure: Screen and recoat.

Peeling

The finish delaminates from the floor in sheets.

Prevention: Avoid the following:

  • Stain or previous finish coat that was not dry.
  • Skipping abrasion between finish coats.
  • Stain not sufficiently wiped up.
  • Improper tacking between coats.
  • Surface contamination such as wax or oil-soap cleaners.
  • Finishes that are not compatible.

Cure: Re-sand and recoat.

Picture Framing (“Halo”)

The edges of the room appear to be a slightly different color than the rest of the room.

Prevention: Avoid sanding the edges of a room differently than the field, which causes edges to be either smoother or rougher than the center of the floor, affecting the finish and/or stain appearance.

Cure: Re-sand the floor, being sure to use the same sanding procedure on all parts of the floor.

Pin Holes

Similar to fisheyes, but very small.

Prevention: do not apply a coat of finish over one that was not yet dry.

Cure: Give the floor sufficient time to totally dry, then screen and recoat using correct dry times between coats.

Poly Beads

Droplets (“BB’s”) of finish that form along strip edges. They can be soft and sticky when first formed, but become hard if left undisturbed.

Prevention: Avoid slow drying conditions and excessive amounts of sealer and/or finish, which seeps into cracks.

Cure: Time will allow the floor to expand and contract, eventually allowing all of the undried finish to surface. When soft, the beads can be smeared, leaving an unsightly appearance that may require screening and recoating. For hardened beads, the solution is to remove them with a sharp edge (i.e. scraper or plastic putty knife) and, if necessary, screen and recoat. Do not attempt to screen the hardened beads, which will cause circular scratches within the finish.

Roughness/Grain Raise

The surface of the wood floor is rough to the touch.

Prevention: Avoid the following:

  • Inadequate sanding, including skipping too many grits.
  • Contamination of the finish during dry time.
  • Not allowing sufficient dry time for waterborne sealers to flatten.
  • Moisture causing the wood grain to rise.
  • Not using enough coats of waterborne finish.

Cure: If a moisture problem is evident, this must be corrected before rescreening and recoating.

Shellout/Dishing of Springwood

Uneven wear between segments of annual rings.

Prevention: Following sound maintenance practices, such as changing casters to wide, non-marking rubber.

Cure: Sand and refinish.

Sidebonding/Panelization

The problems appear similar, but are different. With sidebonding, the bottoms of the edges of the individual strips are “glued” together by the finish. This can occur with all types of finish, although it happens more frequently with water-based products. Panelization occurs when the edges of boards are crushed and stick together as a result.

Prevention: Staining floors can help prevent sidebonding, which results from the finish seeping down into the spaces between boards and gluing the bottoms together. Panelization can happen when staples crack the tongue in some areas and not others, or when a wet plywood subfloor shrinks as it dries.

Cure: Restoring normal humidity levels can return thefloor to an acceptable appearance. If there still are gaps, see “Gaps, Abnormal.” If these methods do not fix the floor, floor replacement may be necessary.

Slivers/Splinters

Slivers and/or splinters protrude from the surface of the floor, especially at the edges of the boards. May tend to occur more frequently in beveled prefinished products and wire brushed products.

Prevention: Take steps to prevent unevenness caused by: expansion, cupping, subfloor irregularities, edge crushing from expansion, or grain raise from moisture. Take care not to damage the floor when nailing during the installation process, and follow proper grading guidelines.

Cure: If a new floor is producing fibers, not splinters, buff vigorously with a commercial buffer and nylon polishing pad. For slivered bevels, shave off with a razor knife and re-stain. For expansion, cupping and grain raise, correct the moisture source.

For wind shake, it may be possible to repair the boards using low viscosity, CA (cyanoacrylate) adhesive (such as Super Glue). Apply the adhesive under the seam of the shake. The adhesive will wick down and hold the shake. Because it is clear and nonambering,it can even be used between coats of finish. Or, the boards can be removed and replaced.

Squeaky/Loose Floors (“Popping”)

The floor causes objectionable squeaks or other noises.
Extra Resource: Fixing Squeaky Floors

Prevention: Squeaky floors are caused by problems in the wood flooring system, subfloor system or underfloor supports. Take precautions to insure these areas are sound during installation. Avoid inadequate or improper nailing, using a weak subfloor or improper subfloor material, or insufficient/incorrect adhesive.

Cure: Noises in only certain areas may be fixed by injecting adhesive into the problem area, screwing the floor down from below, strengthening the subfloor from below or using facenails or screws and plugs. Squeaks also may be lubricated with graphite, wax or baby powder, although such solutions will contaminate the floor for future finishing.

Floors that are noisy and loose throughout the entire area usually have to be pulled and reinstalled, correcting the problem—whether it is caused by the subfloor, fastening schedule or adhesive.

Stains

Discoloration on one area of the floor.

Prevention: Avoid the following:

  • Liquids spilled onto hardwood floors.
  • Pet stains
  • Residue from improper cleaners.
  • Continual moisture leading to mildew (black), decay (brown/white) or alkaline conditions (white).

Cure: Cloudy surface finish can be fixed by lightly rubbing with a proper cleaner and buffing, although some stains require screening and recoating. Pet stains sometimes can be fixed by re-sanding, but frequently require total board replacement. One technique to eliminate pet stains is to apply naval gel (a phosphoric acid gel commonly available at hardware stores) to wick the tannins out of the area. This will not contaminate the floor for future finishing or leave a halo mark, as attempts at bleaching the floor often do.

Sticker Stain

Light brown marks that appear on the wood surface, especially on maple, ash or other light woods. They occur across the width of the strip, measure 3⁄4 to 1 inch wide and occur about every 20 to 24 inches down the length of individual strips.

Prevention: Sticker stain is allowed in second-and-better-grade maple and No. 1 common oak. If the marks will be objectionable to the owner, do not install the flooring.

Sticker stain generally does not sand out.

Sticky Board Syndrome

The finish will not adhere or cure properly on one or more boards.

Prevention: Do not apply too much stain, and then finish, over very open grain. Another cause of sticky board is excessive tannic acid or pH imbalance in the wood. This is most common with oil-modified finishes and white oak.

Cure: When one board or several boards scattered throughout the floor will not take stain or finish, the most common solution is to repair the floor by replacing the boards. Or, boards may be taped off (using recommended tape) and scraped or hand sanded, then coated with a water-based sealer. After proper dry time, they may then be coated with an oil-modified finish. Trowel filling may help prevent sticky board syndrome.

Unevenness of Entire Floor

The entire floor as a unit appears to be uneven.
Extra Resource: How Subfloors Affect Flooring

Prevention: Unevenness can be caused by uneven, warped and loose subfloors, joists that are warped or fractured, settled support pillars or perimeter foundation. Unevenness can also be caused by a cracked and/or settled concrete slab. Although structural integrity of the subfloor system is not the responsibility of wood flooring contractors, they should check the floor for flatness before beginning an installation.

Cure: A general contractor needs to repair the subfloor before the wood floor can be repaired.

Uneven Sheen Levels

The sheen of the finish is inconsistent.

Prevention: Avoid the following:

  • Insufficient mixing of finish prior to application.
  • Uneven sanding.
  • Uneven finish thickness.
  • A contaminated finish applicator, such as a lanolin-rich lambswool applicator that hasn’t been thoroughly cleaned.
  • Inspecting the floor under inadequate lighting.

Cure: Screen and recoat. If lighting is the cause, discuss with the customer the reasonable inspection position for looking at a hardwood floor—from a standing position under normal lighting conditions.

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Hardwood Flooring Reference Tool & Definitions

by | Jan 21, 2020 |

Quick reference guide for hardwood tools & definitionsAbove Grade A suspended floor located above ground level, with a minimum of 18 inches of ventilated air space below. Normally above a basement, but a suspended floor may also be above a crawl space. Abrasion...