D03D - MATERIAL GUIDES - SPECIES
D03D-1 Hardwood
D03D-2 Hardwood cuts
D03D-3 Hardwood appearance
D03D-4 Harwood grain and texture
D03D-5 Hardwood hardness
D03D-6 Hardwood workability
D03D-7 Hardwood species
D03D-8 Domestic (North American) hardwood species
D03D-9 Imported hardwood species
D03D-10 Domestic (North American) softwood species
D03D-11 Imported softwood species
D03D-12 Non-wood species
D03D-13 Relative hardness or Janka table
D03D-2 Hardwood cuts
D03D-3 Hardwood appearance
D03D-4 Harwood grain and texture
D03D-5 Hardwood hardness
D03D-6 Hardwood workability
D03D-7 Hardwood species
D03D-8 Domestic (North American) hardwood species
D03D-9 Imported hardwood species
D03D-10 Domestic (North American) softwood species
D03D-11 Imported softwood species
D03D-12 Non-wood species
D03D-13 Relative hardness or Janka table
Preface:
This reference guide is a discussion of hardwood species that are used in hardwood and engineered hardwood strip, plank, and parquet flooring systems.
1 • HARDWOOD
This reference guide is a discussion of hardwood species that are used in hardwood and engineered hardwood strip, plank, and parquet flooring systems.
1 • HARDWOOD
.01 A variety of domestic (North American, i.e., Canada and continental United States) and imported (Central and South America, Europe, Asia, Africa, and Australia) species are available and used in the manufacturing of hardwood flooring. These include both hardwoods and some softwoods.
.02 Each species possesses different characteristics that make it unique. Most of these become evident when the wood is cut. Different cuts will produce wood pieces with different features and qualities. |
2 • HARDWOOD CUTS
.01 Hardwood flooring lumber is either plain-sawn, quarter-sawn, or rift-sawn.
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.02 Plain-Sawn 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. Since most of the lumber produced by plain sawing is flat-grained, with some vertical-grained wood included, plain-sawn lumber will tend to contain more variation within and among boards than quarter-sawn lumber, in which nearly all of the wood is vertical-grained. Also, since flat-grained wood is less dimensionally stable than vertical-grained, plain-sawn lumber will tend to expand and contract more across the width of the boards than quarter-sawn lumber.
Other physical differences to consider when choosing plain-sawn lumber rather than quarter-sawn: |
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.03 Quarter Sawn lumber is produced by first quartering the log and then sawing each "quarter" perpendicular to the growth rings. Quarter sawing produces relatively narrow boards, nearly all vertical-grained, and creates more waste, making quarter-sawn lumber more expensive than plain-sawn. However, much quarter-sawn wood is obtained by culling the vertical-grained wood that naturally results from plain sawing.
For reasons other than cost, most individuals prefer quarter-sawn wood, although some favour the variety in figuring produced in plain sawing. Other physical factors to keep in mind when choosing quarter-sawn over plain-sawn wood are: |
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.04 Rift sawn lumber is similar to quarter sawing, with many of the same advantages and limitations. It accentuates the vertical grain and minimizes the flake effect common in quarter-sawn 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. Rift sawing creates more waste than quarter sawing, making it generally more expensive.
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3 • HARDWOOD APPEARANCE
1. Heartwood / Sapwood
.01 Heartwood: 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.
.02 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. .03 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, quarter-sawn and rift-sawn flooring which contain less sapwood than plain-sawn flooring, 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. |
2. Wood Discolouration
Causes
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Cures
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4 • HARDWOOD GRAIN AND TEXTURE
.01 Grain and texture are loosely used to describe similar properties of wood.
.02 Grain: is often used in reference to annual growth rings, as in "fine" or "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. |
.1 Tangential Grain: Usually called flat grain; easily recognized 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.
.2 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 90owith the wide surface of the board. Note: In hardwoods, plain-sawn lumber generally contains mostly flat-grained wood, while quarter-sawn lumber is nearly all vertical-grained. In softwood lumber the terms "flat-grained" and "vertical-grained" are used instead of the terms "plain-sawn" and "quarter-sawn", respectively. Refer to Types of Saw Cuts below. .3 Interlocked Grain: Grain in which the fibres may slope in a right-handed direction several years, then 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. |
.03 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.
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.04 Wood Grain Terminology:
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.1 Annual / Growth 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 rings, formed first, is called "spring wood"; the outer part, formed later in the season, is called "summer wood".
.2 Spring wood: is characterized by cells having relatively large cavities and thin walls. .3. Summer wood: is characterized by cells having smaller cavities and thicker walls, and consequently they 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. .4 Figure: The pattern produced in a wood surface by annual growth rings, rays, knots, and deviations from regular grain. .5 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 quarter-sawn lumber in certain species. |
5 • HARDWOOD HARDNESS
.01 One of the more important properties for wood used in flooring applications is its hardness. This is important in determining the ability of a wood species to withstand denting, marring, and wear. It is also a good indicator of how hard a species is to saw / machine and fasten.
.02 Janka Rating: One method of measuring the hardness of wood is based on a variation of the Brinell hardness test known as the Janka test which measures the load required to embed an 11.28 mm (0.444") diameter steel ball to one-half its depth into a selected species of wood. The results are stated in various ways in different countries, which can lead to confusion, especially since the name of the actual units employed is often not attached. In North America, the measurement is in pounds-force. In Sweden it is in kilogram-force (kgf), and in Australia, Janka hardness ratings are either in newtons (N) or kilonewtons (kN). Sometimes the results are treated as units, e.g., "360 janka." |
.03 The hardness of wood usually varies with the direction of the grain. If testing is done on the surface of a plank, the test is said to be of "side hardness". End (i.e end of board) testing is also sometimes done. Testing the cut surface of a stump would also be a test of end hardness. The side hardness of teak, for example, is in the range 3730 to 4800 newtons, while the end hardness is in the range 4150 to 4500 newtons. The most common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring.
.04 The side hardness of wood in regard to flooring represents the resistance of the wood to denting, marring, and wear. A Janka rating for a hardwood floor species is based on an average of side hardness test results for both tangential and radial (i.e. plain-sawn and quarter-sawn) samples under wet and dry (12% moisture content) conditions. .05 A relative hardness rating listing of wood species used in hardwood flooring is attached at the end of this Part of the NFCA Reference Manual. The higher the rating; the harder the wood. It must be noted however that although this is one of the best methods to measure the ability of wood species to withstand indentations, it should be used as a general guide only when comparing various species of wood flooring. The construction and finish used also play an important role in the durability and ease of maintenance of any wood floor. |
6 • HARDWOOD WORKABILITY
.01 The workability of a wood species in regard to its use for flooring depends on the cut.
.02 Machining: This depends on several factors, including density, extent of interlocked or variable grain, hard mineral deposits, and tensions in wood that may cause fibrous and fuzzy surfaces. The degree of checking and separation present will also affect machining ease. Interlocked grain is characteristic of many tropical forest species and causes problems in planing quarter-sawn or rift-sawn boards unless sharpness of knives, cutting angles, and feed rates are carefully controlled. Hard deposits in the cells, such as silica and calcium carbonate, may have a pronounced dulling effect on cutting tools. This effect generally increases as wood is dried to normal working requirements. .03 Fastening: When fastening some of the denser woods using hand or air powered fasteners (nailers) installers may encounter splitting tongues, as well as failure to secure the fastener even after repeated attempts. This can sometimes be corrected by changing the fastener point of entry. On certain exceptionally dense species, pilot holes may have to be drilled to ease nailing or screwing. Blunting the ends of fasteners may also help prevent splitting. Though dense, heavy woods normally offer higher fastener withdrawal resistance, less dense species allow the use of more and larger diameter fasteners to compensate for their lower holding ability. .04 Sanding: Some wood species are highly resinous and tend to clog sandpaper. When working with such species, it may be necessary to use a coarser grit of sandpaper than normal, or to change the sandpaper more often than with other species. Also, the wood dust created by sanding some species may cause an allergic reaction in some people. This is more likely to occur with imported species than with domestic. However, even North American oak has been known to cause skin rash or respiratory difficulties in some individuals. Where this may be a problem, long sleeved shirts, dust masks, and eye protection should be used when sanding. When working with any type of wood refer to the flooring manufacturer's material safety data sheets (MSDS) for hazards in regard to wood dust particularly during sanding. |
7 • HARDWOOD SPECIES
.01 A variety of domestic (North American) and imported species (from Europe, Asia, Africa, and Australia) of tree wood is available and used in the manufacturing of hardwood flooring in general.
.02 Design authorities must also be aware of the difference between "marketing" names and the actual species name. Some imported hardwoods are marketed as traditional North American species such as oak, maple, and cherry. For example, so-called "Tasmanian oak" is not oak at all but an Australian eucalyptus. "Brazilian Cherry" isn't cherry either, and "Malaysian Oak" actually is rubberwood from tropical rubber tree plantations. In addition, the colour, grain pattern, hardness, and luster of many imported woods differ from those of North American hardwoods. Whatever the species chosen, the design authority must consult local manufacturers and suppliers in regard to availability and suitability. .03 The following list of domestic and imported hardwoods and softwoods is provided for general information only. |
8 • DOMESTIC (NORTH AMERICAN) HARDWOOD SPECIES
A number of North American hardwood species are used for flooring material. The following species are not in any order of preference or usage. Other species may also be used and the design authority must consult local manufacturers and suppliers in regard to characteristics listed herein.
.01 Ash (Fraxinus Americana) from North America. Other varieties are also available from Central and South America.
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.02 American Beech (Fagus Grandifolia) / European Beech(Fagus Sylvatica) similar.
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.1 General:FagusFsylvaticaFgrandifolia -
.2 Appearance: Heartwood is reddish brown and sapwood is pale white. .3 Grain: Mostly closed, straight grain, uniform texture. Coarser than European Beech. .4 Hardness Rating: (Janka Table) 1300 or 8% harder than Northern Red Oak. .5 Durability: Elastic, hard; excellent shock resistance. Wears well, stays smooth when subjected to friction - popular for factory floors. .6 Workability: |
.a Machining / Sawing: Good with machine tools, difficult to work with hand tools.
.b Fastening: Good holding ability; has tendency to split. .c Sanding: Satisfactory. .d Finishing: No known problems. |
.03 Yellow Birch (Betula alleghaniensis) / Birch (Betula spp.)
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.1 Appearance: Heartwood is light reddish brown tinged with red, and sapwood is creamy yellow (or pale white in yellow Birch). Sweet birch has light coloured sapwood and heartwood is dark brown tinged with red.
.2 Grain: Medium figuring, generally straight, closed grain with fine uniform texture. Occasional curly grain or wavy figure in some boards. .3 Hardness Rating: (Janka Table) 1260 or 2.3% softer than Northern Red Oak. .4 Durability: Hard and stiff, and very strong withgood crushing strength and shock resistance. It dries rather slowly with little degrade, but it has moderately high shrinkage, so is susceptible to movement in performance. .5 Workability: |
.a Machining / Sawing: Good with machine tools; difficult with hand tools.
.b. Fastening: N. .c. Sanding: Satisfactory. .d Finishing: To known problems. |
.04 American Black Cherry (Prunus serotina)
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.1 General: Prunus is a genus of 120 to 400 species that contain fruitwoods like cherry, plum, and almond. The species are native to North America, Asia, Europe, and the Mediterranean region. All species look alike microscopically. The word prunus is the classical Latin name for the cherry tree. Prunus serotina in North America includes American cherry, black wild cherry, cabinet cherry, chisos wild cherry, Edwards Plateau cherry, escarpment cherry, gila chokecherry, mountain black cherry, rum cherry, southwest choke cherry, southwestern chokecherry, wild black cherry, wild cherry, whisky cherry.
.2 Appearance: Heartwood is light to dark reddish brown, lustrous; sapwood is light brown to pale with a light pinkish tone. Some manufacturers steam lumber to bleed the darker heartwood colour into the sapwood, resulting in a more uniform colour. .3 Grain: Fine, frequently wavy, uniform texture. True quarter sawn has distinctive flake pattern. Texture is satiny, with some gum pockets. .4 Hardness Rating: (Janka Table) 950 or 26.4% softer than Northern Red Oak. .5 Durability: , moderately hard. Usually considered too soft for an entire floor-mostly used for accents and borders. .6 Workability: |
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.05 American Cypress (Taxodium distichum)
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.1 General: Other names include Bald cypress, Red cypress, Yellow cypress, and Southern cypress. Cypress trees are conifers, but unlike most softwood, these are deciduous trees that shed foliage in the fall like hardwoods. Although cypress is softwood, it grows alongside hardwoods and traditionally has been grouped and manufactured with hardwoods.
.2 Appearance: S .3 Hardness Rating: (Janka Table) 1375 or 6.6% harder than Northern Red Oak. .4 Durability: . .5 Workability: |
.a Machining / Sawing: .
.b Fastening: Nails and screws very well. .c Sanding: Easy / well. .d Finishing: Readily accepts finishes with no known problems. |
.06 Elms:
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3. Soft Elms:
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.04 Red Elm:
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.07 Hickory and Pecan-Hickory (Carya spp.)
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.08 Hard Maple - Sugar Maple (Acer saccharum), Black Maple (Acer nigrum)
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.1 General: Hard Maple is a hard and heavy wood with good strength properties; in particular it has high resistance to abrasion and wear. It also has good steam-bending properties.
.2 Appearance: Heartwood varies from creamy white to light to dark reddish brown. Sapwood is pale to creamy white with a slight reddish brown tinge. The amount of darker brown heartwood can vary significantly according to growing region. Both sapwood and heartwood can contain pith fleck. .3 Grain: Generally closed, fine / subdued straight grain, with uniform texture, but occasionally may have quilted, fiddle back, curly or bird's-eye figuring. Figured boards often culled during grading and sold at a premium. .4 Hardness Rating: (Janka Table) 1450 or 12.4% harder than Northern Red Oak. .5 Durability: Dense, strong, stiff, often used in bowling alleys and sports floors. .6 Workability: Dries slowly with high shrinkage, so can be susceptible to movement in performance. With care it machines well. |
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.09 Soft Maple - Red Maple (Acer rubrum), Silver Maple (Acer saccharinum). Other Names: Box Elder
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.10 Mesquite (Prosopis glandulosa)
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.1 Appearance: Colour: Light brown to dark reddish brown.
.2 Grain: High in character, with ingrown bark and mineral streaks. Used in end-grain flooring blocks. .3 Hardness Rating: (Janka Table) 2345 or 82% harder than Northern Red Oak. .4 Durability: Dense and very strong. Susceptible to termites and pinhole bores. .5 Workability |
.a Machining / Sawing: Works easily with most tools.
.b. Fastening: Pre-boring necessary for nailing. .c Sanding: Good with end grain requiring #16 grit paper to cut properly. .d Finishing: No known problems, finishes smoothly, does not take a high polish. |
.11 Oak (Quercus spp.) - General Comments
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.1 Red Oak (Quercus Erythrobalanus)
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.2 White Oak (Quercus Leucobalanus / Quercus alba)
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.12 Sycamore (Platanus occidentalis) Other Names: Buttonwood, Plane tree.
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.13 Black Walnut (Juglans nigra), also referred to as American Black Walnut
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9 • IMPORTED HARDWOOD SPECIES
.01 Brazilian Cherry or Jatoba (Hymenaea, courbaril) From Central and South America (not a cherry tree)
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.02 Australian Cypress (Callitris glauca) Actually a pine tree (softwood)
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.03 Jarrah (Eucalyptus marginata) From Western Australia (a eucalyptus tree)
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.04 Mahogany - Santos (Myroxylon balsamum) From Central and South America. Other varieties are also available from the same areas.
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.05 Merbau (Ipil, kwila Intsia spp) From South East Asia.
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.06 Padauk (Pterocarpus soyauxii) From Central Africa
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.07 Purpleheart (Amaranth, Peltogyne spp) from Central and South America
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.08 Rubberwood or Parawood or Heveawood (Hevea brasiliensis)
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7. Substitution: Rubberwood is an effective substitute for Asian ramin, Meranti, Seraya, Agathis, Merbau, Kapur, Teak, African sapelli, Iroko, Kosipo & Obeche, Latin (South) American Imbula & Virola, Lauan, Nyatoh.
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.09 Teak - Thia / Burmese (Tectona grandis)
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.10 Wenge or Panga-Panga (Millettia spp.)
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.11 Other Imported Hardwood Species
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10 • DOMESTIC (NORTH AMERICAN) SOFTWOOD SPECIES
The following North American softwood species are commonly used for the purposes of flooring:
.01 Douglas Fir (Pseudotsuga menziesii)
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.02 Hemlock (Tsuga mertensiana) from North America (Pacific Coast)
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.03 Heart Pine - Antique (Pinus spp.)
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.04 Southern Yellow Pine (Pinus spp.)
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11 • IMPORTED SOFTWOOD SPECIES
.01 Imported softwood species include:
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12 • NON-WOOD SPECIES
.01 Bamboo
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13 • RELATIVE HARDNESS OR JANKA TABLE
.01 The following page on Janka hardness ratings is provided for information only. These and other ratings for species not listed must be verified from ratings provided by an appropriate independent (third party) testing agency. One source, amongst many, for this information is the Centre for Wood Anatomy Research of the U.S. Forest Service at www2.fpl.fs.fed.us
.02 The following Janka ratings are based on side testing samples of air-dried wood with a moisture content of 12%. The higher the number, the harder the wood is www.fpl.fs.fed.us |
RELATIVE HARDNESS OR JANKA TABLE
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