WOOD SPECIES USED IN WOOD FLOORING
Introduction: An Overview of Wood Properties
Wood is a dynamic medium. Like all organic materials, it has character and quirks, responds to its environment, and changes over time. Because of its “personality,” wood should be treated with understanding and a certain amount of care. For wood flooring professionals, knowing about the properties of wood in general, as well as those of individual wood species, is critical to proper installation. For consumers, it’s important to have realistic expectations about how wood will perform. Most wood used for flooring is essentially a by-product of more expensive wood-consuming industries (furniture manufacture, for example), so it is usually not the highest grade of lumber. However, it is quite economical in comparison. This publication provides an overview of the mechanical and physical properties of wood, followed by more detailed information on several species used in flooring. In selecting the species described, the aim has been to offer a fair sampling of some of today’s most popular woods. Other species may be included in later editions of this publication.
Note: The samples chosen to illustrate each species were selected to be as representative as possible. In most cases, the samples are plainsawn, select or better grade flooring. However, there are many variations within each species, and the methods used in sanding and finishing will affect the final appearance of a given species. Also, the samples were photographed only a few days after being sanded and finished. Some species, such as domestic cherry, will change colour significantly over time. Therefore, the appearance of any installation may vary from the samples shown in this publication.
The character of wood
As a flooring material, wood is superior to vinyl or carpet, both practically and aesthetically. A solid wood floor is more than a covering; it adds strength and stability to the floor system. A one-inch thickness of wood has the same insulating value as 15 inches of concrete. Wood is durable and long-lasting — occasional sanding and refinishing essentially results in a brand-new floor. Wood floors don’t retain mildew or absorb dust, simplifying cleaning. Perhaps the most appealing characteristics of wood flooring, though, are its attractive appearance and natural warmth. A beautiful wood floor can enliven a drab room, enhance any architectural style, complement furniture and design schemes, and adds value to any home or building. A combination of qualities should be considered when selecting a species for flooring: appearance related attributes such as texture, grain and colour, as well as mechanical properties like dimensional stability, durability, machinability and ease in finishing; and finally, availability and cost.
Properties affecting appearance
Many different factors, from the nature of the living tree to the way the lumber is sawed, affect the way the finished floor will look.
HEARTWOOD, SAPWOOD: Heartwood is the older, harder central portion of a tree. It usually contains deposits of various materials that frequently give it a darker colour than sapwood. It is denser, less permeable and more durable than the surrounding sapwood. Sapwood is the softer, younger outer portion of a tree that lies between the cambium (formative layer just under the bark) and the heartwood. It is more permeable, less durable and usually lighter in colour than the heartwood. The relative amounts of heartwood and sapwood in a flooring batch may affect the way it accepts stain and finish and, therefore, the finished appearance of the floor. In general, quartersawn and riftsawn flooring will contain less sapwood than plainsawn flooring (see “Types of saw cut,” next page), and will tend to have a straighter grain and more uniform appearance. Heartwood is also more dimensionally stable than sapwood, so flooring with a high percentage of heartwood will shrink and swell less than flooring that is mostly sapwood.
WOOD GRAIN AND TEXTURE: “Grain” and “texture” are loosely used to describe similar properties of wood. Grain is often used in reference to annual growth rings, as in “fine” “coarse” grain; it is also used to indicate the direction of fibres, as in straight, spiral and curly grain. The direction of the grain, as well as the amount of figuring in the wood, can affect the way it is sanded and sawed. Grain is also described as being either “open” or “closed,” referring to the relative size of the pores, which affects the way a wood accepts stain and finishes. Texture usually refers to the finer structure of the wood, rather than to the annual rings. It is sometimes used to combine the concepts of density and degree of contrast between spring wood and summer wood in the annual growth rings.
Some wood grain terminology
Annual rings: Most species grown in temperate climates produce visible annual growth rings that show the difference in density and colour between wood formed early and that formed late in the growing season. The inner part of the growth ring, formed first, is called “spring wood”; the outer part, formed later in the season, is called “summer wood.” Spring wood is characterised by cells having relatively large cavities and thin walls. Summer wood cells have smaller cavities and thicker walls, and consequently are denser than those in spring wood. The growth rings, when exposed by conventional sawing methods, provide the grain or characteristic pattern of the wood. The distinguishing features among the various species result in part, then, from differences in growth-ring formation. And within species, natural variations in growth ensure the unique character and beauty of each piece of wood.
Figure: The pattern produced in a wood surface by annual growth rings, rays, knots, and deviations from regular grain.
Medullary Rays: Medullary rays extend radially from the core of the tree toward the bark. They vary in height from a few cells in some species, to four or more inches in the oaks; they’re responsible for the flake effect common to the quartersawn lumber in certain species.
Tangential Grain: Usually called flat grain; easily recognised by its parabolic (arched) effect. Lumber is considered “flat-grained” when the annual growth rings make an angle of less than 45 degrees with the wide surface of the board.
Radial Grain: Known as vertical or edge grain; generally more dimensionally stable than flat grain — that is, vertical-grain boards are less likely to expand or contract in width with changes in moisture. Lumber is considered “vertical-grained” when the annual growth rings make an angle of 45 to 90 degrees with the wide surface of the board.
(Note: In hardwoods, plainsawn lumber generally contains mostly flat-grained wood, while quartersawn lumber is nearly all vertical-grained. In softwood lumber, the terms “flat-grained” and “vertical-grained” are used instead of the terms “plainsawn” and “quartersawn,” respectively. See “Types of saw cut” below.)
Interlocked Grain: Grain in which the fibres may slope in a right-handed direction for several years, in a left-handed direction for several years, back to right-handed, and so on. A high degree of interlocked grain may make a wood difficult to machine.
TYPES OF SAW CUT: Lumber is either plainsawn, quartersawn or riftsawn.
Plainsawing is the most common and least expensive method of sawing; most wood flooring is cut this way. Plainsawn lumber is obtained by making the first saw cut on a tangent to the circumference of the log and remaining cuts parallel to the first. This method is the most economical, because it provides the widest boards and results in the least waste.
Since most of the lumber produced by plainsawing is flatgrained, with some vertical-grained wood included, plainsawn lumber will tend to contain more variation within and among boards than quartersawn lumber, in which nearly all of the wood is vertical-grained. Also, since flat-grained wood is less dimensionally stable than vertical-grained, plainsawn lumber will tend to expand and contract more across the width of the boards than quartersawn lumber.
Other physical differences to consider when choosing plainsawn lumber rather than quartersawn:
• Figure patterns resulting from the annual rings and some other types of figures are usually brought out more conspicuously by plainsawing.
• Shakes and pitch pockets, when present, extend through fewer boards.
In quartersawing, lumber is produced by first quartering the log and then sawing perpendicular to the growth rings. Quartersawing produces relatively narrow boards, nearly all vertical-grained, and creates more waste, making quartersawn lumber more expensive than plainsawn. However, much quartersawn wood is obtained by culling the vertical-grained wood that naturally results from plainsawing. For reasons other than cost, most people prefer quartersawn wood, although some people favor the greater variety in figuring produced in plainsawing. Other physical factors to keep in mind when choosing quartersawn lumber over plainsawn:
• It twists and cups less.
• It surface-checks and splits less during seasoning and in use.
• Raised grain produced by separation in the annual growth rings does not appear as pronounced.
• It wears more evenly.
• Figuring due to pronounced rays, interlocked and wavy grain are brought out more conspicuously.
• Sapwood appears only at the edges, and is limited to the width of the sapwood in the log.
Riftsawing is similar to quartersawing, with many of the same advantages and limitations. It accentuates the vertical grain and minimizes the flake effect common in quartersawn oak. The angle of the cut is changed slightly so that fewer saw cuts are parallel to the medullary rays, which are responsible for the flake effect. Riftsawing creates more waste than quartersawing, making it generally more expensive.
Mechanical properties
MOISTURE CONTENT AND DIMENSIONALSTABILITY: Moisture plays a large part in how wood behaves, both during the machining process and after installation. Installers would do well to study moisture’s effect on wood in some detail; however, a brief discussion is worthwhile here. Moisture content is defined as the weight of water in wood expressed as a percentage of the weight of oven-dry wood. Weight, shrinkage, strength and other properties depend on the moisture content of wood. In trees, moisture content may be as much as 200 percent of the weight of wood substance. After harvesting and milling, the wood will be dried to the proper moisture content for its end use. Wood is dimensionally stable when the moisture content is above the fibre saturation point (usually about 30 percent moisture content). Below that, wood changes dimension when it gains or loses moisture. The ideal moisture content for flooring installation can vary from an extreme of 4 to 18 percent, depending on the wood species, the geographic location of the end product and the time of year. Most oak flooring, for example, is milled at 6 to 9 percent. Before installation, solid wood flooring should be acclimated to the area in which it is to be used, then tested with a moisture meter to ensure the proper moisture content.
(Note: Laminated flooring tends to be more dimensionally stable than solid flooring, and does not require acclimation prior to installation.)
Different woods exhibit different moisture stability factors, but they generally shrink and swell the most in the direction of the annual growth rings (tangentially), about half as much across the rings (radially) and only slightly along the grain (longitudinally). This means that plainsawn flooring will tend to shrink and swell more in width than quartersawn flooring, and that most flooring will not shrink or swell much in length.
The individual species descriptions that follow include an indication of dimensional stability, from “below average” to “excellent,” as well as a comparison to red oak. For example, mesquite (the most dimensionally stable species in this publication) is rated as “excellent,” with a notation that it is 65 percent more stable than red oak — that is, mesquite is likely to shrink or swell 65 percent less. The percentages noted are based on comparing a factor called the “dimensional change coefficient” of each species with that of red oak. Red oak was chosen as the benchmark because of its widespread familiarity and use in the flooring industry. For a comparison of the relative dimensional stability of several species, measured by the dimensional change coeffiicient, refer to the chart on page 7. For wood flooring professionals, it’s important to inform end users about the normal behaviour of wood in relation to moisture. Most solid wood flooring will contract during periods of low humidity (during the heating season, for example), sometimes leaving noticeable cracks between boards. To minimise this effect, users should stabilise the environment of the building through temperature and humidity control.
HARDNESS AND DURABILITY: Probably the most important strength property for wood used in flooring applications is its side hardness, also known as Janka hardness. Side hardness represents the resistance of wood to wear, denting and marring. It is measured by the load
WOOD SPECIES USED IN WOOD FLOORING
ASH WOOD FLOORS
WHITE
1994 NATIONAL WOOD FLOORING ASSOCIATION 9
N AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A
Appearance
COLOUR: Heartwood is light tan to dark brown; sapwood is creamy white. Similar in appearance to white oak, but frequently more yellow.
GRAIN: Bold, straight, moderately open grain with occasional wavy figuring. Can have strong contrast in grain in plainsawn boards.
VARIATIONS WITHIN SPECIES AND GRADES:
Sometimes confused with hickory; the zone of large pores is more distinctive in ash, similar to that of red oak.
Properties
HARDNESS/JANKA: 1320; 2% harder than Northern red oak.
DIMENSIONAL STABILITY: Above average (change coefficient .00274; 26% more stable than red oak).
DURABILITY: Elastic, hard; excellent shock resistance. Remains smooth under friction.
Workability
SAWING/MACHINING: Good machining qualities.
SANDING: Sands satisfactorily.
NAILING: Good holding ability; good resistance to splitting.
FINISHING: No known problems. Stains well.
COMMENTS:
Availability
Moderately available.
BEECH WOODEN FLOORS
Appearance
COLOUR: In yellow birch (B. alleghaniensis), sapwood is creamy yellow or pale white; heartwood is light reddish brown tinged with red. In sweet birch (B. lenta), sapwood is light coloured and heartwood is dark brown tinged with red.
GRAIN: Medium figuring, straight, closed grain, even texture. Occasional curly grain or wavy figure in some boards.
VARIATIONS WITHIN SPECIES AND GRADES: Yellow birch, sweet birch, paper birch. Paper birch (B.
papyrifera) is softer and lower in weight and strength than yellow or sweet birch. However, yellow birch is
most commonly used for flooring. Boards can vary greatly in grain and colour.
Properties
SIDE HARDNESS/JANKA: 1260 (yellow); 2% softer than Northern red oak.
DIMENSIONAL STABILITY: Average (change coefficient .00338; 8% more stable than red oak).
DURABILITY: Hard and stiff; very strong, with excellent shock resistance.
Workability:
SAWING/MACHINING: Difficult to work with hand tools, but good machining qualities.
SANDING: Sands satisfactorily.
NAILING: Excellent holding ability.
FINISHING: No known problems.
COMMENTS:
Availability
Moderately available.
10
BIRCH FLOORING
Appearance
COLOUR: Heartwood is mostly reddish brown; sapwood is generally pale white.
GRAIN: Mostly closed, straight grain; fine, uniform texture. Coarser than European beech.
VARIATIONS WITHIN SPECIES AND GRADES: Only one species is native to the United States. Moderate to high colour variation between boards.
Properties
HARDNESS (JANKA): 1300; 1% harder than Northern red oak.
DIMENSIONAL STABILITY: Below average (change coefficient .00431; 17% less stable than red oak).
DURABILITY: Elastic, hard; excellent shock resistance. Wears well and stays smooth when subjected to friction — popular for factory floors.
Workability
SAWING/MACHINING: Difficult to work with hand tools, but good machining qualities.
SANDING: Sands satisfactorily.
NAILING: Good holding ability, but has a tendency to split.
FINISHING: No known problems.
COMMENTS:
Availability
Limited.
CHERRY BLACK
1994 NATIONAL WOOD FLOORING ASSOCIATION
Appearance
COLOUR: Heartwood is light to dark reddish brown, lustrous; sapwood is light brown to pale with a light pinkish tone. Some flooring manufacturers steam lumber to bleed the darker heartwood colour into the sapwood, resulting in a more uniform colour.
GRAIN: Fine, frequently wavy, uniform texture. Distinctive flake pattern on true quartersawn surfaces. Texture is satiny, with some gum pockets.
VARIATIONS WITHIN SPECIES AND GRADES: Significant colour variation between boards.
Properties
HARDNESS (JANKA): 950; 26% softer than Northern red oak.
DIMENSIONAL STABILITY: Above average (change coefficient .00248; 33% more stable than red oak).
DURABILITY: Strong, moderately hard; excellent shock resistance. Usually considered too soft for an entire floor — mostly used for borders and accents.
Workability
SAWING/MACHINING: Good machining qualities.
SANDING: Sands satisfactorily.
NAILING: Good holding ability.
FINISHING: No known problems.
COMMENTS: High in bending strength. Light-sensitive; strong colour change upon exposure to light.
Availability
Limited.
MAPLE WOOD FLOORING
SUGAR/HARD AT I
O N A L W
Appearance
COLOUR: Heartwood is creamy white to light reddish brown; sapwood is pale to creamy white.
GRAIN: Closed, subdued grain, with medium figuring and uniform texture. Occasionally shows quilted, fiddleback, curly or bird’s-eye figuring. Figured boards often culled during grading and sold at a premium.
VARIATIONS WITHIN SPECIES AND GRADES: Black
maple (B. nigrum) is also hard; other species are classified as soft.
Properties
HARDNESS (JANKA): 1450; 12% harder than Northern red oak.
DIMENSIONAL STABILITY: Average (change coefficient
.00353; 4% more stable than red oak).
DURABILITY: Dense, strong, tough, stiff; excellent shock resistance — often used in bowling alleys and athletic facilities. Markedly resistant to abrasive wear.
Workability
SAWING/MACHINING: Density makes machining difficult.
SANDING: Sands satisfactorily.
NAILING: Fair resistance to splitting; good holding ability.
FINISHING: Takes neutral finish well; does not stain uniformly.
COMMENTS: Light colour lends itself to contemporary light floors. Extra care must be taken during sanding and finishing, as sanding marks and finish lines are more obvious due to maple’s density and light color.
Availability
Commodity item; figured grains limited.
OAK
RED
Appearance
COLOUR: Heartwood and sapwood are similar, with sapwood lighter in colour; most pieces have a reddish tone. Slightly redder than white oak.
GRAIN: Open, slightly coarser (more porous) than white oak. Plainsawn boards have a plumed or flared grain appearance; riftsawn has a tighter grain pattern, low figuring; quartersawn has a flake pattern, sometimes called tiger rays or butterflies.
VARIATIONS WITHIN SPECIES AND GRADES: More than 200 subspecies in North America; great variation in colour and grain, depending on the origin of the wood and corresponding differences in growing seasons. Northern, Southern and Appalachian red oak can all be divided into upland and lowland species. Because they grow more slowly, upland species generally have a more uniform grain pattern than lowland species, with more growth rings per inch.
Properties
HARDNESS (JANKA): Northern 1290 (benchmark).
DIMENSIONAL STABILITY: Average (change coefficient .00369).
DURABILITY: Stiff and dense; resists wear, with high shock resistance, though less durable than white oak.
Workability
SAWING/MACHINING: Above average in all machining operations except shaping.
SANDING: Sands satisfactorily, better than white oak.
NAILING: Good resistance to splitting; excellent holding ability.
FINISHING: Strong stain contrast because of large pores.
COMMENTS: Red oak generally works better than white for bleached floors, because it is more porous and accepts bleach better, and because tannins in white oak can discolour floor.
Availability
Commodity item, available in all types, styles and sizes of flooring, including parquet, strip, plank and veneer, both unfinished and prefinished.
OAK
WHITE
1994 NATIONAL WOOD FLOORING ASSOCIATION 19
Appearance
COLOUR: Heartwood is light brown; some boards may have a pinkish tint or a slight greyish cast. Sapwood is white to cream.
GRAIN: Open, with longer rays than red oak. Occasional crotches, swirls and burls. Plainsawn boards have a plumed or flared grain appearance; riftsawn has a tighter grain pattern, low figuring; quartersawn has a flake pattern, sometimes called tiger rays or butterflies.
VARIATIONS WITHIN SPECIES AND GRADES: Considerable variation among boards in colour and grain texture, but variations not as pronounced as in red oak.
Properties
HARDNESS (JANKA): 1360; 5% harder than Northern red oak.
DIMENSIONAL STABILITY: Average (change coefficient .00365; 1% more stable than red oak).
DURABILITY: More durable than red oak. Tannic acid in the wood protects it from fungi and insects.
Workability
SAWING/MACHINING: Excellent machining qualities.
SANDING: Sands satisfactorily.
NAILING: Good resistance to splitting; excellent holding ability.
FINISHING: Absorbs finishes more evenly than red oak. Does not bleach well.
COMMENTS: During the finishing process, tannins at the surface can react with some liquids to turn the wood green or brown. This effect tends to be more pronounced with products that have a high water content, such as bleach and water-based finishes.
Availability
Commodity item, available in nearly all types, styles and sizes of flooring, including parquet, strip, plank and veneer, both unfinished and prefinished.
WALNUT - AMERICAN BLACK
Appearance
COLOUR: Heartwood ranges from a deep, rich dark brown to a purplish black. Sapwood is nearly white to tan. Difference between heartwood and sapwood colour is great; some flooring manufacturers steam lumber to bleed the darker heartwood colour into the sapwood, resulting in a more uniform colour.
GRAIN: Mostly straight and open, but some boards have burled or curly grain. Arrangement of pores is similar to hickories and persimmon, but pores are smaller in size.
VARIATIONS WITHIN SPECIES AND GRADES: Great variety of colour and figure within species, as well as variation in colour among boards, especially in lower grades and from material that isn’t steamed prior to kiln-drying.
Properties
HARDNESS (JANKA): 1010; 22% softer than Northern red oak.
DIMENSIONAL STABILITY: Excellent (change coefficient .00274; 26% more stable than red oak).
DURABILITY: Moderately dense, very strong, good shock resistance. Not as dent-resistant as oak.
Workability
SAWING/MACHINING: Easily worked with hand tools, and has excellent machining qualities.
SANDING: Sands satisfactorily.
NAILING: Fair resistance to splitting; good holding ability.
FINISHING: Finishes nicely, with a handsome grain pattern.
COMMENTS: Distinctive sweet aroma when worked. Frequently used as a highlight material for borders or other inlay techniques.
Relative availability
Moderately available, normally in unfinished parquet, strip and in various plank widths as a special order. Available in fancy parquet patterns as a special order or custom mill.
JARRAH WOOD FLOORING
Appearance
COLOUR: Heartwood is uniformly pinkish to dark red, often a rich, dark red mahogany hue, turning a deep brownish red with age and exposure; sapwood is pale. Frequent black streaks with occasional ingrown grain.
GRAIN: Frequently interlocked or wavy. Texture is even and moderately coarse.
VARIATIONS WITHIN SPECIES AND GRADES: Moderate to high colour variation.
Properties
HARDNESS (JANKA): 1910; 48% harder than Northern red oak.
DIMENSIONAL STABILITY: Below average (change coefficient .00396; 7% less stable than red oak).
DURABILITY: Dense and very strong; high resistance to wear.
Workability
SAWING/MACHINING: Difficult to work because of high density and irregular grain; carbide tooling recommended.
SANDING: Sands well, but dust can stain fabric and wall treatments.
NAILING: Good holding ability.
FINISHING: Red colour can bleed into some finishes — a problem when mixing species.
COMMENTS: Resistant to termites and fungus.
Availability
Moderately available.
MERBAU
Appearance
COLOUR: Heartwood is yellowish to orange-brown when freshly cut, turning brown or dark red-brown upon exposure.
GRAIN: Straight to interlocked or wavy; coarse texture.
VARIATIONS WITHIN SPECIES AND GRADES: Moderate to high variation in colour.
Properties
HARDNESS (JANKA): 1925; 49% harder than Northern red oak.
DIMENSIONAL STABILITY: Excellent (change coefficient .00158; 57% more stable than red oak). However, actual installations have demonstrated significant movement in use.
DURABILITY: Strength is comparable to hickory, but density is somewhat lower.
Workability
SAWING/MACHINING: Sawing is difficult; wood gums saw teeth and dulls cutting edges; carbide tooling recommended.
SANDING: Sands satisfactorily.
NAILING: Good holding ability.
FINISHING: Wood stains black in contact with ferrous metals or moisture.
COMMENTS: High resistance to termites.
Availability
Limited.
Sunday, 20 July 2008
Water & Wood
WATER AND WOOD
1996 NATIONAL WOOD FLOORING ASSON AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T 0
Water and Wood Basics
The easy explanation that students learn in school — trees grow with roots in the ground and leaves in the air — still serves as the basis for understanding the never-ending relationship between water and wood. The roots collect moisture and nutrients from the soil and ship them through vessels or fibres up the trunk and branches to the leaves. These vessels are similar to the “strings” in a stalk of celery. They are similar, too, to a group of soda straws gathered together, running up and down the tree. That’s the simple version of how a still-standing tree is made up of vertically aligned fibres. Cut the tree down, and the fibres are horizontal. Saw it and manufacture strip flooring, nail the floor down and most of the fibres are still horizontal, running the length of the boards. In the live tree, the fibres are loaded with moisture, as sap. After being cut, the tree begins to dry out, just like a rose will wilt after it’s picked. As the tree’s fibres dry, they shrink in thickness or diameter, but almost none lengthways. This shrinkage, characteristic of all woods, is critical in understanding the effect of moisture on wood flooring.
Moisture content in solid wood is defined as the weight of water in wood expressed as a percentage of the weight of oven-dry wood. Weight, shrinkage, strength and other properties depend on the moisture content of wood. In trees, moisture content may be as much as 200 percent of the weight of wood substance.
After harvesting and milling, the wood will be dried to the proper moisture content for its end use.
Wood fibres are dimensionally stable when the moisture content is above the fibre saturation point
(usually about 30 percent moisture content). Below that, wood changes dimension when it gains or loses moisture. Here are some quick points about shrinking and swelling:
• Shrinkage usually begins at 25 to 30 percent moisture content, the fibre saturation point. Shrinkage continues to zero percent moisture content, an oven-dry state.
• Swelling occurs as wood gains moisture, when it moves from zero to 25 to 30 percent moisture content, the fibre saturation point. Different woods exhibit different moisture stability factors, but they always shrink and swell the most in the direction of the annual growth rings (tangentially), about half as much across the rings (radially) and only in minuscule amounts along the grain (longitudinally).
This means that plainsawn flooring will tend to shrink and swell more in width than quartersawn flooring, and that most flooring will not shrink or swell measurably in length.
• Generally, flooring is expected to shrink in dry environments and expand in wetter environments.
• Between the fibre saturation point and the ovendry state, wood will only change by about .1 percent of its dimension along the grain (lengthways in a flatsawn board). It will change by 2 to 8 percent across the grain and across the annular rings (top to bottom), if quartersawn; and 5 to 15 percent across the grain and parallel to the annular rings (side to side), if plainsawn.
• Wider boards tend to move more than narrower boards. Movement in a 5-inch-wide plank is more dramatic than in a 21/4-inch strip. The ideal moisture content for flooring installation can vary from an extreme of 4 to 18 percent, depending on the wood species, the geographic location of the end product and time of year. Most oak flooring, for example, is milled at 6 to 9 percent.
A wood’s weight and moisture content
Wood is hygroscopic — meaning, when exposed to air, wood will lose or gain moisture until it is in equilibrium with the humidity and temperature of the air.
Moisture content (MC) from 5 to 25 percent may be determined using various moisture meters developed for this purpose. The most accurate method in all cases, and for any moisture content, is to follow the laboratory procedure of weighing the piece with moisture, removing the moisture by fully drying it in an oven (105 degrees C) and re-weighing. The equation for determining moisture content is weight of wood with water - oven-dry weight MC% = x 100 oven-dry weight
AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T I O
Wood Flooring Over Radiant Heating
Radiant heating is a growing source of heating in North America, both in residential and commercial installations. Consequently, it’s important for installers to understand how radiant heating works with hardwood flooring installations. Radiant heating does not heat air directly, as do more conventional forms of heating, such as baseboard convectors or forced air circulation. Radiant heat is “omni-directional.” Unlike warm air, which tends to rise, radiant energy tends to travel in all directions. A large area of mild surface temperatures, such as a warm floor, is capable of transferring as much heat as a small surface area, such as a steam radiator, at high surface temperatures.
Radiant heat beneath wood flooring involves tubing in concrete, or tubing under plywood subfloors. The most important factor in a successful wood flooring installation over radiant heat is a dry slab and a dry subfloor. The only sure way to dry a slab and subfloor system is to turn on the radiant heating system before installing the wood flooring.
If this isn’t done, moisture left in the slab will enter the wood flooring as soon as the heat is turned on. The result is floors that will expand, contract, shrink, crack, cup and bow excessively. If the heat can’t be turned on, then everyone involved — down to the homeowner — should understand and accept the compromises that will appear down the road. Opinions on the amount of time required vary widely. Some say the heating system should be turned on at least 72 hours before installation, with a preferred time of five to six days. That assumes that the slab has been in place for at least 60 days. (See “Testing concrete” on page 16.) If the slab is relatively new, the recommendation is to have the heating system turned on for 30 to 60 days before installing wood floors. As always, follow the recommendations of your wood flooring manufacturer. Wood dries rapidly when the heat is first turned on. It dries to a lower moisture content toward the end of the heating season. When the radiant heat is turned off, moisture once again starts to seep into the wood subfloor and radiant slab. Abruptly turning on the radiant heat in the fall will subject wood flooring to rapid and easily noticed movement: Evidence of this movement will be cupping or crowning of the boards. Finally, shrinkage cracks will appear between individual floor boards. Alternatively, gradually turning the heat on before the first really cool day will begin the seasonal movement more gradually.
Thus, the movement of the floor will be much less noticeable. As always, humidity controls can help offset flooring expansion and contraction.
Not all species of wood are good candidates for an installation over radiant heating. It’s best to follow the manufacturer’s recommendation for a species’ suitability over radiant heat. When possible, choose a species that is known for its stability. Quartersawn or rift-sawn flooring is preferable to plainsawn in the search for stability. Strip flooring is also a better choice than plank flooring, because narrow boards expand and contract less than wide boards do. Using narrow boards also means there are more seams in a floor to take up movement. Because of its dimensional stability, laminated flooring is another good choice.
Radiant heating systems are currently designed to run cooler than they did years ago, although water supplied to the systems generally range from 90 degrees to 140 degrees. In years past, when water temperatures exceeded 140 degrees, wood fibres were repeatedly traumatised, causing stress fractures, gaps and twisting. Repeated heating and cooling also broke down the adhesive that bonded the hardwood to the slab.
But today, a set of thermostat controls can help avoid those problems. It is recommended to have three thermostats — one to control the tubing water supply temperature; one to control the room temperature with different zone controls; and one for outside the house. This three-thermostat system is kindest to wood flooring, because it moderates the floor temperature.
People tend to crank up the heat when they’re cold, but with three thermostats, the system adapts itself to conditions both inside and out. The outside thermostat gears up the system for the arrival of colder weather, and a thermostat adjusting the control water temperature on the tubing will keep the temperature at the homeowner’s comfort level.
1996 NATIONAL WOOD FLOORING ASSON AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T 0
Water and Wood Basics
The easy explanation that students learn in school — trees grow with roots in the ground and leaves in the air — still serves as the basis for understanding the never-ending relationship between water and wood. The roots collect moisture and nutrients from the soil and ship them through vessels or fibres up the trunk and branches to the leaves. These vessels are similar to the “strings” in a stalk of celery. They are similar, too, to a group of soda straws gathered together, running up and down the tree. That’s the simple version of how a still-standing tree is made up of vertically aligned fibres. Cut the tree down, and the fibres are horizontal. Saw it and manufacture strip flooring, nail the floor down and most of the fibres are still horizontal, running the length of the boards. In the live tree, the fibres are loaded with moisture, as sap. After being cut, the tree begins to dry out, just like a rose will wilt after it’s picked. As the tree’s fibres dry, they shrink in thickness or diameter, but almost none lengthways. This shrinkage, characteristic of all woods, is critical in understanding the effect of moisture on wood flooring.
Moisture content in solid wood is defined as the weight of water in wood expressed as a percentage of the weight of oven-dry wood. Weight, shrinkage, strength and other properties depend on the moisture content of wood. In trees, moisture content may be as much as 200 percent of the weight of wood substance.
After harvesting and milling, the wood will be dried to the proper moisture content for its end use.
Wood fibres are dimensionally stable when the moisture content is above the fibre saturation point
(usually about 30 percent moisture content). Below that, wood changes dimension when it gains or loses moisture. Here are some quick points about shrinking and swelling:
• Shrinkage usually begins at 25 to 30 percent moisture content, the fibre saturation point. Shrinkage continues to zero percent moisture content, an oven-dry state.
• Swelling occurs as wood gains moisture, when it moves from zero to 25 to 30 percent moisture content, the fibre saturation point. Different woods exhibit different moisture stability factors, but they always shrink and swell the most in the direction of the annual growth rings (tangentially), about half as much across the rings (radially) and only in minuscule amounts along the grain (longitudinally).
This means that plainsawn flooring will tend to shrink and swell more in width than quartersawn flooring, and that most flooring will not shrink or swell measurably in length.
• Generally, flooring is expected to shrink in dry environments and expand in wetter environments.
• Between the fibre saturation point and the ovendry state, wood will only change by about .1 percent of its dimension along the grain (lengthways in a flatsawn board). It will change by 2 to 8 percent across the grain and across the annular rings (top to bottom), if quartersawn; and 5 to 15 percent across the grain and parallel to the annular rings (side to side), if plainsawn.
• Wider boards tend to move more than narrower boards. Movement in a 5-inch-wide plank is more dramatic than in a 21/4-inch strip. The ideal moisture content for flooring installation can vary from an extreme of 4 to 18 percent, depending on the wood species, the geographic location of the end product and time of year. Most oak flooring, for example, is milled at 6 to 9 percent.
A wood’s weight and moisture content
Wood is hygroscopic — meaning, when exposed to air, wood will lose or gain moisture until it is in equilibrium with the humidity and temperature of the air.
Moisture content (MC) from 5 to 25 percent may be determined using various moisture meters developed for this purpose. The most accurate method in all cases, and for any moisture content, is to follow the laboratory procedure of weighing the piece with moisture, removing the moisture by fully drying it in an oven (105 degrees C) and re-weighing. The equation for determining moisture content is weight of wood with water - oven-dry weight MC% = x 100 oven-dry weight
AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T I O
Wood Flooring Over Radiant Heating
Radiant heating is a growing source of heating in North America, both in residential and commercial installations. Consequently, it’s important for installers to understand how radiant heating works with hardwood flooring installations. Radiant heating does not heat air directly, as do more conventional forms of heating, such as baseboard convectors or forced air circulation. Radiant heat is “omni-directional.” Unlike warm air, which tends to rise, radiant energy tends to travel in all directions. A large area of mild surface temperatures, such as a warm floor, is capable of transferring as much heat as a small surface area, such as a steam radiator, at high surface temperatures.
Radiant heat beneath wood flooring involves tubing in concrete, or tubing under plywood subfloors. The most important factor in a successful wood flooring installation over radiant heat is a dry slab and a dry subfloor. The only sure way to dry a slab and subfloor system is to turn on the radiant heating system before installing the wood flooring.
If this isn’t done, moisture left in the slab will enter the wood flooring as soon as the heat is turned on. The result is floors that will expand, contract, shrink, crack, cup and bow excessively. If the heat can’t be turned on, then everyone involved — down to the homeowner — should understand and accept the compromises that will appear down the road. Opinions on the amount of time required vary widely. Some say the heating system should be turned on at least 72 hours before installation, with a preferred time of five to six days. That assumes that the slab has been in place for at least 60 days. (See “Testing concrete” on page 16.) If the slab is relatively new, the recommendation is to have the heating system turned on for 30 to 60 days before installing wood floors. As always, follow the recommendations of your wood flooring manufacturer. Wood dries rapidly when the heat is first turned on. It dries to a lower moisture content toward the end of the heating season. When the radiant heat is turned off, moisture once again starts to seep into the wood subfloor and radiant slab. Abruptly turning on the radiant heat in the fall will subject wood flooring to rapid and easily noticed movement: Evidence of this movement will be cupping or crowning of the boards. Finally, shrinkage cracks will appear between individual floor boards. Alternatively, gradually turning the heat on before the first really cool day will begin the seasonal movement more gradually.
Thus, the movement of the floor will be much less noticeable. As always, humidity controls can help offset flooring expansion and contraction.
Not all species of wood are good candidates for an installation over radiant heating. It’s best to follow the manufacturer’s recommendation for a species’ suitability over radiant heat. When possible, choose a species that is known for its stability. Quartersawn or rift-sawn flooring is preferable to plainsawn in the search for stability. Strip flooring is also a better choice than plank flooring, because narrow boards expand and contract less than wide boards do. Using narrow boards also means there are more seams in a floor to take up movement. Because of its dimensional stability, laminated flooring is another good choice.
Radiant heating systems are currently designed to run cooler than they did years ago, although water supplied to the systems generally range from 90 degrees to 140 degrees. In years past, when water temperatures exceeded 140 degrees, wood fibres were repeatedly traumatised, causing stress fractures, gaps and twisting. Repeated heating and cooling also broke down the adhesive that bonded the hardwood to the slab.
But today, a set of thermostat controls can help avoid those problems. It is recommended to have three thermostats — one to control the tubing water supply temperature; one to control the room temperature with different zone controls; and one for outside the house. This three-thermostat system is kindest to wood flooring, because it moderates the floor temperature.
People tend to crank up the heat when they’re cold, but with three thermostats, the system adapts itself to conditions both inside and out. The outside thermostat gears up the system for the arrival of colder weather, and a thermostat adjusting the control water temperature on the tubing will keep the temperature at the homeowner’s comfort level.
Maintenance of Wood Flooring
4 © 2000 NATIONAL WOOD FLOORING ASSOCIATION0
MAINTENANCE
Importance of Maintenance
Unlike most floor coverings, wood floors are a long-term investment that, correctly maintained, will last the lifetime of the home. Fortunately for consumers, today’s wood floors offer a wide spectrum of product options that are easy to maintain. Unlike times past, when people had to get down on their knees to buff their wax floors, taking care of wood floors today requires little effort. The routine maintenance involves protecting the finish from scratches and moisture. If consumers avoid both of those things, they’ve got a handle on most of their wood floor care.
MAINTENANCE AND RECOATING OF HARDWOOD FLOORS
When maintained properly, wood floor finishes can look beautiful for years to come
4 © 2000 NATIONAL WOOD FLOORING ASSOCIATION0
All Floors
While specific finish types may require different maintenance, some guidelines apply to the care of all wood floors. First, before furniture is placed onto the wood floor, floor protector pads should be installed on the bottom of all furniture legs. Also, rugs should be placed at all entrances to the area (check with the finish manufacturer for when these can be placed. Most should not go down on the floor for at least seven days, and sometimes more than 21 days after the finish is applied). These rugs help trap grit and also absorb moisture before either one has a chance to damage the finish. Rugs should be shaken out, cleaned and thoroughly dried when they get wet. Take special precautions with non-skid pads that are frequently placed under area rugs. These pads may imprint their pattern onto the finish and/or wood floor.
(Natural fibres may not transfer as much as synthetic pads.) Also, be aware that area rugs may cause colour differences in the floor due to differences in light exposure. Consumers should expect that their floors would shrink and expand with changes in humidity, sometimes leaving small cracks between boards. To minimise the changes, it is recommended that consumers use some kind of humidity control in their homes.
Routine basic maintenance includes sweeping, vacuuming and/or dust-mopping to remove dirt and grit. (Use only vacuums that have a special hard-surface setting.) The more that dirt and grit are allowed to accumulate, the more they will be tracked over the floor, leaving scratches. Some manufacturers recommend lightly damp-mopping a floor, while others do not. Regardless, household dust treatments should never be used. All shoes, especially high heels, should be kept in good repair — if they lose their protective cap, they will dent the surface of any floor. Pet nails need to be trimmed regularly to prevent finish and wood damage. Be especially attentive to potential spill areas, such as dishwashers, sinks, icemakers and stovetops. Other potential problem spots include household plants and Christmas tree stands. Consumers see the best results if they develop a cleaning schedule and stick to it. In addition to their regular schedule, they should be aware that not only should they clean the floor immediately after a major event, they should clean immediately before it. (The increased traffic on the floor will result in more damage from any dirt or grit present on the floor.)
Those are some of the basics. For information specific to finish types, read the following sections.
WHAT TO USE?
It is important to impress upon consumers exactly which directions to follow and which products to use in caring for their wood floors. Although Mr. Smith may use cleaning product X, his floor may have a finish totally different from Mrs. Brown’s finish next door.
For pre-finished wood floors, consumers should follow the directions of the flooring manufacturer as to which cleaning products to use. This is extremely important, because not following those directions may void the manufacturer’s warranty of the wood floor.
Consumers with floors that were finished at the job site should follow the maintenance directions of the floor finish manufacturer.
In either case, using a non-recommended product to clean the floor may ruin the appearance of the finish, and also may cause problems down the road when it is time for the floor to be recoated. If it is unknown who the manufacturer is, the customer should follow the general guidelines detailed on the next page.
DO use floor protectors DO vacuum often DON’T use wet mops
© 2000 NATIONAL WOOD FLOORING ASSOCIATION 5
SURFACE FINISHES
Maintenance tips specific to surface-type finishes (water-based urethane, oil-modified polyurethane, conversion varnish and moisture cured urethane) include:
• As with any wood floor, follow a program of cleaning, sweeping and vacuuming to eliminate as much dirt and grit as possible, and remember that moisture should not come in contact with the floor. If it does, it should be wiped up immediately.
• Always use manufacturers’ recommended cleaning products, which won’t leave a contaminating residue on the floor. If the manufacturer is not known, use a generic hardwood floor cleaner available at local retail wood flooring stores.
• Most warranties from finish manufacturers and factory-finished wood flooring manufacturers are voided by use of oil soap cleaners.
• Wipe up spills immediately with a lightly dampened cloth, then follow up with a recommended cleaning product.
• For stubborn stains, lightly dampen a soft cloth with a manufacturer’s recommended cleaner or a generic hardwood floor cleaner. Apply directly to the stain and repeat as necessary.
• Never use a wax finish on top of a surface finish.
• When the floor loses its lustre, the floor needs help. There are options available to revive the floor. A topcoat dressing may revive the floor’s appearance. Or, the floor may need to be screened/padded and recoated.
WAX FINISH
Maintenance tips specific to wax-type finishes include:
• Wipe up spills immediately with a dry cloth.
Buffing may be required.
• To remove white spots caused by water spills, use a fine steel wool and a small amount of mineral spirits. Rub gently in a circular motion until the spot is gone, and then rewax the area and rebuff.
• When the floor loses its lustre in heavy traffic areas, buff those areas with a polishing brush or pad. If that does not restore lustre, rewax only those areas and buff. Note that too much wax causes the floor to scuff easily.
• Conditioners and cleaners are available on the market to be applied to wax floors, which can then be coated over with another coat of wax. Pay careful attention to manufacturer’s directions as to how long such cleaners should remain on the floor.
• Eventually (after many years), the floor will need to be stripped and rewaxed. Even if waxed floors are completely sanded down, they may be very difficult to coat over with a surface finish.
ACRYLIC-IMPREGNATED
Acrylic-impregnated floors are generally available in two types: those with a urethane coating and those without, and their care varies accordingly.
Non-urethane-coated acrylic impregnated floors need a regular maintenance routine of sweeping, vacuuming or dust-mopping. Beyond that, however, their care differs significantly from most other floor finishes:
• Use a low-speed buffing machine with the appropriate pad and recommended cleaning product as necessary. Depending on the manufacturer, different pads may be recommended for different steps in the cleaning process.
DON’T use dust cleaner DO use throw rugs DON’T use ammonia
6 © 2000 NATIONAL WOOD FLOORING ASSOCIATION
N AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T I O 1 0
• Use recommended dust mop treatments to enhance dust mopping.
• For white/bleached products, always use an untreated mop — never any water or petroleum-based products. The floor should be buffed with a low-speed buffer and a recommended product specifically for white/bleached floors. (More maintenance will be required of white/bleached floors than other colours.)
• Some manufacturers recommend that floors that have become dull be lightly screened, to be followed up with a recommended cleaner and recommended conditioning product.
• Follow manufacturers’ directions for spot cleaning stubborn stains. Methods include spot sanding or screening and then applying the recommended cleaner and conditioner.
Other methods include using mineral spirits or hydrogen peroxide and a hand-sized piece of pad to remove the stain.
Note that recoating such floors with urethane will void the manufacturer’s warranty.
Urethane-coated acrylic-impregnated floors also require routine maintenance of sweeping, vacuuming or dust mopping, but they do not need the commercial-type equipment recommended for non-urethane products.
Recommendations include:
• Damp-mop using a cleaner recommended by urethane finish manufacturers. Damp mopping with water should not be part of routine maintenance.
• For light scratches, apply a light wax coat to the scratched area. Deeper scratches or damage may require spot sanding, refinishing and resealing by a hardwood floor professional. Some manufacturers also have touch-up kits available.
SPORTS FLOORS
Sports floors, from basketball courts to aerobics studios, usually take a beating of heavy daily use.
General guidelines include the following:
• DO dry mop the floor daily with a properly treated dust mop. Floors with especially heavy use should be swept up to three times a day.
• DO use walk-off mats at all doorways.
• DO wipe up spills or any other moisture on the floor immediately.
• DO remove heel marks using an approved wood floor cleaner applied with a soft cloth or a dust mop.
• DO make sure the heating/ventilating/air conditioning system is working properly, with normal humidity levels. Indoor relative humidities should be between 35 and 50 percent year-round. In areas of consistently high or low outside humidity, a 15 percent fluctuation will not adversely affect the maple.
• DO inspect the floor for abnormal tightening or shrinkage. In wet weather, carefully monitor doors and windows for water leakage.
• DO remove debris from expansion voids.
• DO NOT shut down the system for a prolonged period of time.
• DO NOT use household cleaning products, which damage the floor finish and also may leave the floor slippery or sticky.
• DO NOT clean the floor with scrubbing machinery or power scrubbers.
MAINTENANCE
Importance of Maintenance
Unlike most floor coverings, wood floors are a long-term investment that, correctly maintained, will last the lifetime of the home. Fortunately for consumers, today’s wood floors offer a wide spectrum of product options that are easy to maintain. Unlike times past, when people had to get down on their knees to buff their wax floors, taking care of wood floors today requires little effort. The routine maintenance involves protecting the finish from scratches and moisture. If consumers avoid both of those things, they’ve got a handle on most of their wood floor care.
MAINTENANCE AND RECOATING OF HARDWOOD FLOORS
When maintained properly, wood floor finishes can look beautiful for years to come
4 © 2000 NATIONAL WOOD FLOORING ASSOCIATION0
All Floors
While specific finish types may require different maintenance, some guidelines apply to the care of all wood floors. First, before furniture is placed onto the wood floor, floor protector pads should be installed on the bottom of all furniture legs. Also, rugs should be placed at all entrances to the area (check with the finish manufacturer for when these can be placed. Most should not go down on the floor for at least seven days, and sometimes more than 21 days after the finish is applied). These rugs help trap grit and also absorb moisture before either one has a chance to damage the finish. Rugs should be shaken out, cleaned and thoroughly dried when they get wet. Take special precautions with non-skid pads that are frequently placed under area rugs. These pads may imprint their pattern onto the finish and/or wood floor.
(Natural fibres may not transfer as much as synthetic pads.) Also, be aware that area rugs may cause colour differences in the floor due to differences in light exposure. Consumers should expect that their floors would shrink and expand with changes in humidity, sometimes leaving small cracks between boards. To minimise the changes, it is recommended that consumers use some kind of humidity control in their homes.
Routine basic maintenance includes sweeping, vacuuming and/or dust-mopping to remove dirt and grit. (Use only vacuums that have a special hard-surface setting.) The more that dirt and grit are allowed to accumulate, the more they will be tracked over the floor, leaving scratches. Some manufacturers recommend lightly damp-mopping a floor, while others do not. Regardless, household dust treatments should never be used. All shoes, especially high heels, should be kept in good repair — if they lose their protective cap, they will dent the surface of any floor. Pet nails need to be trimmed regularly to prevent finish and wood damage. Be especially attentive to potential spill areas, such as dishwashers, sinks, icemakers and stovetops. Other potential problem spots include household plants and Christmas tree stands. Consumers see the best results if they develop a cleaning schedule and stick to it. In addition to their regular schedule, they should be aware that not only should they clean the floor immediately after a major event, they should clean immediately before it. (The increased traffic on the floor will result in more damage from any dirt or grit present on the floor.)
Those are some of the basics. For information specific to finish types, read the following sections.
WHAT TO USE?
It is important to impress upon consumers exactly which directions to follow and which products to use in caring for their wood floors. Although Mr. Smith may use cleaning product X, his floor may have a finish totally different from Mrs. Brown’s finish next door.
For pre-finished wood floors, consumers should follow the directions of the flooring manufacturer as to which cleaning products to use. This is extremely important, because not following those directions may void the manufacturer’s warranty of the wood floor.
Consumers with floors that were finished at the job site should follow the maintenance directions of the floor finish manufacturer.
In either case, using a non-recommended product to clean the floor may ruin the appearance of the finish, and also may cause problems down the road when it is time for the floor to be recoated. If it is unknown who the manufacturer is, the customer should follow the general guidelines detailed on the next page.
DO use floor protectors DO vacuum often DON’T use wet mops
© 2000 NATIONAL WOOD FLOORING ASSOCIATION 5
SURFACE FINISHES
Maintenance tips specific to surface-type finishes (water-based urethane, oil-modified polyurethane, conversion varnish and moisture cured urethane) include:
• As with any wood floor, follow a program of cleaning, sweeping and vacuuming to eliminate as much dirt and grit as possible, and remember that moisture should not come in contact with the floor. If it does, it should be wiped up immediately.
• Always use manufacturers’ recommended cleaning products, which won’t leave a contaminating residue on the floor. If the manufacturer is not known, use a generic hardwood floor cleaner available at local retail wood flooring stores.
• Most warranties from finish manufacturers and factory-finished wood flooring manufacturers are voided by use of oil soap cleaners.
• Wipe up spills immediately with a lightly dampened cloth, then follow up with a recommended cleaning product.
• For stubborn stains, lightly dampen a soft cloth with a manufacturer’s recommended cleaner or a generic hardwood floor cleaner. Apply directly to the stain and repeat as necessary.
• Never use a wax finish on top of a surface finish.
• When the floor loses its lustre, the floor needs help. There are options available to revive the floor. A topcoat dressing may revive the floor’s appearance. Or, the floor may need to be screened/padded and recoated.
WAX FINISH
Maintenance tips specific to wax-type finishes include:
• Wipe up spills immediately with a dry cloth.
Buffing may be required.
• To remove white spots caused by water spills, use a fine steel wool and a small amount of mineral spirits. Rub gently in a circular motion until the spot is gone, and then rewax the area and rebuff.
• When the floor loses its lustre in heavy traffic areas, buff those areas with a polishing brush or pad. If that does not restore lustre, rewax only those areas and buff. Note that too much wax causes the floor to scuff easily.
• Conditioners and cleaners are available on the market to be applied to wax floors, which can then be coated over with another coat of wax. Pay careful attention to manufacturer’s directions as to how long such cleaners should remain on the floor.
• Eventually (after many years), the floor will need to be stripped and rewaxed. Even if waxed floors are completely sanded down, they may be very difficult to coat over with a surface finish.
ACRYLIC-IMPREGNATED
Acrylic-impregnated floors are generally available in two types: those with a urethane coating and those without, and their care varies accordingly.
Non-urethane-coated acrylic impregnated floors need a regular maintenance routine of sweeping, vacuuming or dust-mopping. Beyond that, however, their care differs significantly from most other floor finishes:
• Use a low-speed buffing machine with the appropriate pad and recommended cleaning product as necessary. Depending on the manufacturer, different pads may be recommended for different steps in the cleaning process.
DON’T use dust cleaner DO use throw rugs DON’T use ammonia
6 © 2000 NATIONAL WOOD FLOORING ASSOCIATION
N AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T I O 1 0
• Use recommended dust mop treatments to enhance dust mopping.
• For white/bleached products, always use an untreated mop — never any water or petroleum-based products. The floor should be buffed with a low-speed buffer and a recommended product specifically for white/bleached floors. (More maintenance will be required of white/bleached floors than other colours.)
• Some manufacturers recommend that floors that have become dull be lightly screened, to be followed up with a recommended cleaner and recommended conditioning product.
• Follow manufacturers’ directions for spot cleaning stubborn stains. Methods include spot sanding or screening and then applying the recommended cleaner and conditioner.
Other methods include using mineral spirits or hydrogen peroxide and a hand-sized piece of pad to remove the stain.
Note that recoating such floors with urethane will void the manufacturer’s warranty.
Urethane-coated acrylic-impregnated floors also require routine maintenance of sweeping, vacuuming or dust mopping, but they do not need the commercial-type equipment recommended for non-urethane products.
Recommendations include:
• Damp-mop using a cleaner recommended by urethane finish manufacturers. Damp mopping with water should not be part of routine maintenance.
• For light scratches, apply a light wax coat to the scratched area. Deeper scratches or damage may require spot sanding, refinishing and resealing by a hardwood floor professional. Some manufacturers also have touch-up kits available.
SPORTS FLOORS
Sports floors, from basketball courts to aerobics studios, usually take a beating of heavy daily use.
General guidelines include the following:
• DO dry mop the floor daily with a properly treated dust mop. Floors with especially heavy use should be swept up to three times a day.
• DO use walk-off mats at all doorways.
• DO wipe up spills or any other moisture on the floor immediately.
• DO remove heel marks using an approved wood floor cleaner applied with a soft cloth or a dust mop.
• DO make sure the heating/ventilating/air conditioning system is working properly, with normal humidity levels. Indoor relative humidities should be between 35 and 50 percent year-round. In areas of consistently high or low outside humidity, a 15 percent fluctuation will not adversely affect the maple.
• DO inspect the floor for abnormal tightening or shrinkage. In wet weather, carefully monitor doors and windows for water leakage.
• DO remove debris from expansion voids.
• DO NOT shut down the system for a prolonged period of time.
• DO NOT use household cleaning products, which damage the floor finish and also may leave the floor slippery or sticky.
• DO NOT clean the floor with scrubbing machinery or power scrubbers.
Grading of hardwood flooring
GRADING AND PACKAGING
© 1999 NATIONAL WOOD FLOORING ASSOCIATION 3
Grades were developed to bring a degree of consistency to wood floors.
Introduction: Why We Have Grades
People have been using hardwood floors for hundreds of years — examples can be found in some of the oldest castles and palaces in Europe. In the era when those floors were laid, hardwood floors were constructed by hand in every aspect, from cutting down the lumber to applying the wax.
With the advent of hardwood floor manufacturing machinery, however, an entire industry was born.
While installing, sanding and finishing a floor remained a specialised skill, creating the floors themselves was no longer a painstaking process. Around the turn of the century, mills were established specifically for the production of hardwood floors. Not long after, the burgeoning wood flooring industry saw the need to implement standards, or grades.
Today, nearly a century later, grading is an essential part of doing business in the hardwood floor industry. Grades group flooring with similar qualities, bringing a degree of consistency to products from different mills. Grades tell the purchaser the minimum to expect when buying product, including surface characteristics, required lengths and milling tolerances. Grades also help ensure that money isn’t wasted either by consumers or producers — buyers can confidently expect to get the quality of product they pay for, and manufacturers know they aren’t wasting money by selling high-quality product at a lower-quality price.
In some cases, industry associations, such as the National Oak Flooring Manufacturers Association and the Maple Flooring Manufacturers Association establish grades. The development of hardwood flooring grades was the main impetus in the formation of those groups. In addition to creating grades, the associations provide an impartial party to settle disputes about grading and perform grading inspections.
Manufacturers must be members of such associations to qualify for their grading dispute service. In other cases, hardwood-flooring manufacturers determine their own classifications and create their own grades, or “proprietary grades,” by which they sell their flooring.
-
4 © 1999 NATIONAL WOOD FLOORING ASSOCIATION
N AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T I O N A 5 0
NATIONAL OAK FLOORING
MANUFACTURERS ASSOCIATION
WHO IS NOFMA
The National Oak Flooring Manufacturers Association traces its beginnings to Detroit in 1909, with the formation of the Oak Flooring Manufacturers of the United States. The organisation had several goals: to administer and promote industry-grading rules, to provide statistical data and to act as a general spokesman for the industry.
After being located in Chicago and Cincinnati, the headquarters were moved to Memphis in 1930 and in 1933 the group joined with the Southern Oak Flooring Industries organisation to form NOFMA.
The association was to act as an agency of the Lumber Code authority for the administration of a Code of Fair Competition under provisions of the National Industrial Recovery Act. In 1935, the association’s charter was amended to authorise the organisation to operate as a trade association for the benefit of the producers of oak flooring.
Membership and production through the years peaked in 1955, with 85 member manufacturers and 1.2 billion board feet shipped, and subsequently nose-dived in the 1960s with the popularity of carpeting.
By 1979, membership was less than 10 percent of the 1955 peak. Since 1980, however, it has steadily increased, with shipments in 1997 hitting 416.6 million board feet — the most since 1969.
Today, NOFMA continues its purpose of administering standards, performing quarterly mill inspections, promoting the industry and gathering statistical information. Inspectors check for grade compliance, including milling, packaging length and acceptable moisture levels. NOFMA also strives to educate installers with semi-annual installation schools held in Memphis in conjunction with the National Wood Flooring Association and the Maple Flooring Manufacturers Association. The association provides technical assistance, such as advice on installation, as well. NOFMA’s grades are now accepted so widely that even non-member mills often separate their production of flooring along NOFMA guidelines. In addition to unfinished oak, beech, birch, maple, ash and hickory/pecan, NOFMA has grades for pre-finished oak flooring.
Member mills pledge to support the NOFMA standards to ensure that a NOFMA grade from any member mill will be roughly the equivalent of the same grade from another member mill.
HANDLING OF GRADING DISPUTES
The NOFMA inspection department has the responsibility of rendering complaint inspection reports for member mills. According to NOFMA Rules & Regulations, an impartial opinion will be rendered on matters of controversy between users and member manufacturers. Complaint inspections can be made only on NOFMA member flooring, and can be authorised only by a NOFMA member mill in good standing. The authorisation must be received from the manufacturer whose product is in question. When making inspections,
NOFMA inspectors review pertinent information and inspect job site conditions, installation procedures and the condition of the flooring at the designated site and warehouse, if necessary. They also may provide direction for the removal of sample flooring from the inspection site. Payment to NOFMA for expenses of the complaint inspection is the responsibility of the manufacturer whose flooring is involved. The parties involved determine settlement of the cost of the complaint. Complaint inspection reports are sent to the member manufacturer involved, unless the member has authorised other distribution. When a complaint on grade involves a shipment or installation, if the complaint inspection results in a difference in favour of the purchaser of more than five percent in feet, then the shipper will be considered as being in the wrong. If the difference is only five percent or less in feet, then the party making the complaint is considered as being in the wrong. The quality and condition of the hardwood flooring as it leaves the manufacturer governs the inspection.
NOFMA does not accept any responsibility for:
• The arbitration of claims
• Financial losses to anyone as a result of complaint inspections
• Enforcement of agreements between buyer and seller
• Collection of complaint inspection fees unpaid by flooring users to the manufacturer
• The future performance of flooring when suggestions for correction prove ineffective
PROPRIETARY GRADES
In addition to using standard flooring grades such as those developed by NOFMA, MFMA and CLA, many manufacturers may have their own, or proprietary, grades. There are various reasons for doing this — some producers pick names that are more marketing friendly and further compare them to NOFMA or other grades. Others wish to be either more specific or more general than the industry standards. In other cases, manufacturer standards have been created in response to a void of general standards for specific products. For example, a 3/8- inch engineered floor could be sold as “Vintage” or “Cabin” grades. Because proprietary grades are created by the manufacturer, written descriptions of the grades may not be available to the consumer.
PLANK
Wide-width flooring is usually sold under proprietary grade names; however, NOFMA does have grades for plank flooring. Many U.S. manufacturers have chosen to name their grades using the same terms that are familiar to us from the NOFMA or MFMA standards, such as saying that a product “has some No. 2 Common characteristics.” However, these grades are not certified or verified. If plank producers are NOFMA member mills, they may register their own grade names and detailed descriptions (including average length) with the NOFMA office to qualify for complaint inspection services.
PREFINISHED SOLID
NOFMA does have grading rules for pre-finished solid products, but most manufacturers also create their own proprietary grade names, as well.
Other manufacturers may describe the product by the grade of flooring it was before it was finished, i.e., No. 1 Common, etc. Still others may have brand names such as “Classic” or “Rustic.”
PREFINISHED ENGINEERED
NOFMA now covers engineered flooring under its certification program. Contact NOFMA (contact information is on page 14) for the current information. Also, the Hardwood Plywood & Veneer Association, along with the American National Standards Institute, adopted standards in 1996.
Most manufacturers of engineered product do not create “grades” per se. Instead, they create product names. The products are categorised according to veneer, finish and milling.
While most solid wood flooring products have average length requirements, most engineered floors do not. Generally, many manufacturers’ product names reflect three levels or more of quality ranging from a premium level down to what is generically referred to as cabin grade. At the top level, or premium, the flooring has almost no milling defects and minimal character marks such as knots, mineral streaks or pin worm holes. The next grade, typically a character grade, allows more natural character marks and some minor milling defects that may cause overwood, small finish skips and shorter average lengths. Wood with character marks such as mineral streaks may be used for darker-coloured floors. Cabin-grade floors allow unlimited character marks and milling defects.
Because the industry does not have established grades for engineered floors (aside from the ANSI/ HPVA standards), many purchasers make their decisions about product quality based on the value and the warranty offered. The scope of the warranties decreases accordingly with the quality of the flooring.
Oftentimes, cabin-grade floors offer no warranty.
Complaint Resolution
Most pre-finished engineered flooring manufacturers have a set process for dealing with complaints about the flooring. If a problem cannot be settled between the contractor and consumer, complaint forms are usually routed to the distributor of the product. If they are not settled there, they are sent to the manufacturer, where the flooring — either actual samples from the job site or photographs, along with a written description — is analysed and a final determination is made.
PARQUET
There also are no standard grades in the United States for parquet flooring, although the now-inactive American Parquet Association used to have grades for that segment of the industry. Some parquet manufacturers may still use the names of the APA grades. For unfinished parquet flooring, in ascending order of quality, they are Rustic, Select and Better, and Premium. For pre-finished parquet, they are Cabin, Natural and Better, and Choice. In Canada, CLA grading includes rules for grading the face surface of parquet flooring.
IMPORTED WOOD
Other countries that produce large amounts of hardwood flooring may have their own grades for hardwood floors. In Australia, for example, grades are developed by the Standards Association of Australia and are the same as those used for any hardwood milled products in the country. Australian grades are determined primarily by the face appearance of the products and include, from highest to lowest: clear, select, standard and utility grades. common, etc., the flooring is a mix of grades. Because individual pieces do not have to be cut to divide them into different grades, mill run flooring is typically longer than other flooring. The only flooring sometimes rejected is that with either a manufacturing defect or an unsound board. Due to its mix of grades, mill run flooring is more economical — for both the manufacturer and the consumer.
© 1999 NATIONAL WOOD FLOORING ASSOCIATION 3
Grades were developed to bring a degree of consistency to wood floors.
Introduction: Why We Have Grades
People have been using hardwood floors for hundreds of years — examples can be found in some of the oldest castles and palaces in Europe. In the era when those floors were laid, hardwood floors were constructed by hand in every aspect, from cutting down the lumber to applying the wax.
With the advent of hardwood floor manufacturing machinery, however, an entire industry was born.
While installing, sanding and finishing a floor remained a specialised skill, creating the floors themselves was no longer a painstaking process. Around the turn of the century, mills were established specifically for the production of hardwood floors. Not long after, the burgeoning wood flooring industry saw the need to implement standards, or grades.
Today, nearly a century later, grading is an essential part of doing business in the hardwood floor industry. Grades group flooring with similar qualities, bringing a degree of consistency to products from different mills. Grades tell the purchaser the minimum to expect when buying product, including surface characteristics, required lengths and milling tolerances. Grades also help ensure that money isn’t wasted either by consumers or producers — buyers can confidently expect to get the quality of product they pay for, and manufacturers know they aren’t wasting money by selling high-quality product at a lower-quality price.
In some cases, industry associations, such as the National Oak Flooring Manufacturers Association and the Maple Flooring Manufacturers Association establish grades. The development of hardwood flooring grades was the main impetus in the formation of those groups. In addition to creating grades, the associations provide an impartial party to settle disputes about grading and perform grading inspections.
Manufacturers must be members of such associations to qualify for their grading dispute service. In other cases, hardwood-flooring manufacturers determine their own classifications and create their own grades, or “proprietary grades,” by which they sell their flooring.
-
4 © 1999 NATIONAL WOOD FLOORING ASSOCIATION
N AT I O N A L W O D F L O R I N G A S O C I A T I O N T E C H N I C A L P U B L I C A T I O N A 5 0
NATIONAL OAK FLOORING
MANUFACTURERS ASSOCIATION
WHO IS NOFMA
The National Oak Flooring Manufacturers Association traces its beginnings to Detroit in 1909, with the formation of the Oak Flooring Manufacturers of the United States. The organisation had several goals: to administer and promote industry-grading rules, to provide statistical data and to act as a general spokesman for the industry.
After being located in Chicago and Cincinnati, the headquarters were moved to Memphis in 1930 and in 1933 the group joined with the Southern Oak Flooring Industries organisation to form NOFMA.
The association was to act as an agency of the Lumber Code authority for the administration of a Code of Fair Competition under provisions of the National Industrial Recovery Act. In 1935, the association’s charter was amended to authorise the organisation to operate as a trade association for the benefit of the producers of oak flooring.
Membership and production through the years peaked in 1955, with 85 member manufacturers and 1.2 billion board feet shipped, and subsequently nose-dived in the 1960s with the popularity of carpeting.
By 1979, membership was less than 10 percent of the 1955 peak. Since 1980, however, it has steadily increased, with shipments in 1997 hitting 416.6 million board feet — the most since 1969.
Today, NOFMA continues its purpose of administering standards, performing quarterly mill inspections, promoting the industry and gathering statistical information. Inspectors check for grade compliance, including milling, packaging length and acceptable moisture levels. NOFMA also strives to educate installers with semi-annual installation schools held in Memphis in conjunction with the National Wood Flooring Association and the Maple Flooring Manufacturers Association. The association provides technical assistance, such as advice on installation, as well. NOFMA’s grades are now accepted so widely that even non-member mills often separate their production of flooring along NOFMA guidelines. In addition to unfinished oak, beech, birch, maple, ash and hickory/pecan, NOFMA has grades for pre-finished oak flooring.
Member mills pledge to support the NOFMA standards to ensure that a NOFMA grade from any member mill will be roughly the equivalent of the same grade from another member mill.
HANDLING OF GRADING DISPUTES
The NOFMA inspection department has the responsibility of rendering complaint inspection reports for member mills. According to NOFMA Rules & Regulations, an impartial opinion will be rendered on matters of controversy between users and member manufacturers. Complaint inspections can be made only on NOFMA member flooring, and can be authorised only by a NOFMA member mill in good standing. The authorisation must be received from the manufacturer whose product is in question. When making inspections,
NOFMA inspectors review pertinent information and inspect job site conditions, installation procedures and the condition of the flooring at the designated site and warehouse, if necessary. They also may provide direction for the removal of sample flooring from the inspection site. Payment to NOFMA for expenses of the complaint inspection is the responsibility of the manufacturer whose flooring is involved. The parties involved determine settlement of the cost of the complaint. Complaint inspection reports are sent to the member manufacturer involved, unless the member has authorised other distribution. When a complaint on grade involves a shipment or installation, if the complaint inspection results in a difference in favour of the purchaser of more than five percent in feet, then the shipper will be considered as being in the wrong. If the difference is only five percent or less in feet, then the party making the complaint is considered as being in the wrong. The quality and condition of the hardwood flooring as it leaves the manufacturer governs the inspection.
NOFMA does not accept any responsibility for:
• The arbitration of claims
• Financial losses to anyone as a result of complaint inspections
• Enforcement of agreements between buyer and seller
• Collection of complaint inspection fees unpaid by flooring users to the manufacturer
• The future performance of flooring when suggestions for correction prove ineffective
PROPRIETARY GRADES
In addition to using standard flooring grades such as those developed by NOFMA, MFMA and CLA, many manufacturers may have their own, or proprietary, grades. There are various reasons for doing this — some producers pick names that are more marketing friendly and further compare them to NOFMA or other grades. Others wish to be either more specific or more general than the industry standards. In other cases, manufacturer standards have been created in response to a void of general standards for specific products. For example, a 3/8- inch engineered floor could be sold as “Vintage” or “Cabin” grades. Because proprietary grades are created by the manufacturer, written descriptions of the grades may not be available to the consumer.
PLANK
Wide-width flooring is usually sold under proprietary grade names; however, NOFMA does have grades for plank flooring. Many U.S. manufacturers have chosen to name their grades using the same terms that are familiar to us from the NOFMA or MFMA standards, such as saying that a product “has some No. 2 Common characteristics.” However, these grades are not certified or verified. If plank producers are NOFMA member mills, they may register their own grade names and detailed descriptions (including average length) with the NOFMA office to qualify for complaint inspection services.
PREFINISHED SOLID
NOFMA does have grading rules for pre-finished solid products, but most manufacturers also create their own proprietary grade names, as well.
Other manufacturers may describe the product by the grade of flooring it was before it was finished, i.e., No. 1 Common, etc. Still others may have brand names such as “Classic” or “Rustic.”
PREFINISHED ENGINEERED
NOFMA now covers engineered flooring under its certification program. Contact NOFMA (contact information is on page 14) for the current information. Also, the Hardwood Plywood & Veneer Association, along with the American National Standards Institute, adopted standards in 1996.
Most manufacturers of engineered product do not create “grades” per se. Instead, they create product names. The products are categorised according to veneer, finish and milling.
While most solid wood flooring products have average length requirements, most engineered floors do not. Generally, many manufacturers’ product names reflect three levels or more of quality ranging from a premium level down to what is generically referred to as cabin grade. At the top level, or premium, the flooring has almost no milling defects and minimal character marks such as knots, mineral streaks or pin worm holes. The next grade, typically a character grade, allows more natural character marks and some minor milling defects that may cause overwood, small finish skips and shorter average lengths. Wood with character marks such as mineral streaks may be used for darker-coloured floors. Cabin-grade floors allow unlimited character marks and milling defects.
Because the industry does not have established grades for engineered floors (aside from the ANSI/ HPVA standards), many purchasers make their decisions about product quality based on the value and the warranty offered. The scope of the warranties decreases accordingly with the quality of the flooring.
Oftentimes, cabin-grade floors offer no warranty.
Complaint Resolution
Most pre-finished engineered flooring manufacturers have a set process for dealing with complaints about the flooring. If a problem cannot be settled between the contractor and consumer, complaint forms are usually routed to the distributor of the product. If they are not settled there, they are sent to the manufacturer, where the flooring — either actual samples from the job site or photographs, along with a written description — is analysed and a final determination is made.
PARQUET
There also are no standard grades in the United States for parquet flooring, although the now-inactive American Parquet Association used to have grades for that segment of the industry. Some parquet manufacturers may still use the names of the APA grades. For unfinished parquet flooring, in ascending order of quality, they are Rustic, Select and Better, and Premium. For pre-finished parquet, they are Cabin, Natural and Better, and Choice. In Canada, CLA grading includes rules for grading the face surface of parquet flooring.
IMPORTED WOOD
Other countries that produce large amounts of hardwood flooring may have their own grades for hardwood floors. In Australia, for example, grades are developed by the Standards Association of Australia and are the same as those used for any hardwood milled products in the country. Australian grades are determined primarily by the face appearance of the products and include, from highest to lowest: clear, select, standard and utility grades. common, etc., the flooring is a mix of grades. Because individual pieces do not have to be cut to divide them into different grades, mill run flooring is typically longer than other flooring. The only flooring sometimes rejected is that with either a manufacturing defect or an unsound board. Due to its mix of grades, mill run flooring is more economical — for both the manufacturer and the consumer.
Monday, 14 July 2008
Case Study - Handsawn Oak& Underfloor heating
Interesting case study from McKay Flooring Blog regarding an installation of handsawn oak and underfloor heating.
http://www.mckayflooringblog.com/2008/07/case-study-handsawn-oak-flooring.html
Subscribe to:
Posts (Atom)
