Basics of Hardwood Lumber Grades and Characteristics

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Basics of Hardwood Lumber Grades and Characteristics

Posted On : Aug-25-2011 | seen (428) times | Article Word Count : 890 |

Hardwood lumber in North America is identified by different grading characteristics, colors and dimensions set by the National Lumber Association, which deem a product’s applicability in certain projects as well as its longevity.

Hardwood lumber is a catch-all term encompassing the processed wood from deciduous or leaf-bearing trees. After the trees are harvested they are cut on a head rig into boards of green lumber. Green lumber refers to the fact this wood still contains a high percentage of moisture. Most species require air drying of the boards prior to drying them in kilns. As a general rule, the denser the species, the longer the air drying process is. Most hardwood lumber bought by end-users is kiln dried to the industry standard of 6% to 8% moisture content. At this point the lumber is stable and less subject to movement.

The National Hardwood Lumber Association or NHLA is the primary authority regarding the grading rules for hardwood lumber in North America. Most species, including imported hardwoods sold in the U.S. are graded using these standards as a guide. The NHLA rules book considers the yield of the lumber as related to defects such as knots, splits, wane, cup, twist, side bend, stain and other issues arising from the processing of the wood and from factors inherent in the wood itself.

The three main grades of lumber are FAS (Firsts and Seconds) / Select and Better, which calls for clear face cuttings (free of defects) of 83 1/3% or better. This is the top grade, but it is important to note that it is not graded as completely clear. This grade is used for where long clear cuttings are required for such things as mouldings, windows and doors.

The next grade down is #1C (1 common). This grade requires a minimum of 66 2/3% - 83% clear face cuttings. It is primarily used by cabinet and furniture manufacturers that require shorter clear cuttings.

#2C (2 common) consists of 2a and 2b grades. 2a requires 50%-66 1/3% clear cuttings and 2b requires 50%-66 1/3% sound cuttings. This grade is primarily used by hardwood flooring manufacturers. There is also a 3c grade, but this a little used grade that only requires 33 1/3% yield.

For the vast majority of hardwood lumber buyers in America the question is not one of grade, but of appearance. Appearance falls into two categories, clarity and color. Clarity is the presence or absence of knots, mineral streaks, gum pockets or other natural characteristics. Color primarily refers to heartwood and/or sapwood content of the wood

Heartwood comes from the center of the log and is the lumber from the part of the tree that was dead before the tree was harvested. Sapwood is the outside, living part of the log when it was cut. The sought after color (heart or sap) is relative to the species. In species such as cherry and walnut the more popular color is the heartwood. In Maple the white sapwood commands a premium price. In walnut it is common to steam the green lumber to blend heat and sapwood to create a more uniform look.

In addition to appearance the usage and dimensions play a major role in the proper selection of hardwood lumber. Outdoor applications such as gazebos, siding, decking and lawn furniture require exotic wood such as teak, mahogany, and ipe to withstand the rigors of the elements. The amount of contact or abuse the final application is going to take can also help determine which type of hardwood to use. Alder and Cherry work great for kitchen cabinets, but may not be the best choice for commercial hardwood flooring or stair treads due to their relative softness.

The other factor to consider is the dimension of hardwoods needed. The standard rough (not surfaced) thickness for hardwood lumber is 1”, referred to as 4/4 (pronounced four-quarter). Each 1/4 refers to a 1/4 inch of thickness. 5/4 = 1 1/4” thick, 6/4 is 1 1/2” thick and so on. Hardwood lumber is commonly available in 5/4, 6/4, 8/4 and in limited species and quantities 12/4 and 16/4. Widths are typically random and vary according to specie.

For many buyers dimensional hardwoods are a good choice. Dimensional hardwoods come ripped to your specified width and are also available as s4s (surfaced four sides). Dimensional hardwood lumber is more expensive initially because the milling facility has already incurred the waste, but often the consumer saves money when all is said and done due to time and money saved in processing the lumber as well as the risk of miscalculation of how much raw lumber to purchase is alleviated.

Hardwood lumber is measured in 3 dimensional measurement units called board feet. One board foot is the equivalent of 1” (or less) thick x 12” wide x 12” long. Dimensional hardwoods are measured by length only. A 1 x 6 x 12’ board measures 12 lineal feet. There are several good board foot calculators available on-line to help determine amount of board footage required for a project by converting rip sizes into board feet.

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<h1>Basics of Hardwood Lumber Grades and Characteristics</h1> Author: <a href='http://www.articleseen.com/profile_Richard Milano.aspx'>Richard Milano</a> Hardwood lumber is a catch-all term encompassing the processed wood from deciduous or leaf-bearing trees. After the trees are harvested they are cut on a head rig into boards of green lumber. Green lumber refers to the fact this wood still contains a high percentage of moisture. Most species require air drying of the boards prior to drying them in kilns. As a general rule, the denser the species, the longer the air drying process is. Most hardwood lumber bought by end-users is kiln dried to the industry standard of 6% to 8% moisture content. At this point the lumber is stable and less subject to movement.

The National Hardwood Lumber Association or NHLA is the primary authority regarding the grading rules for hardwood lumber in North America.  Most species, including imported hardwoods sold in the U.S. are graded using these standards as a guide.  The NHLA rules book considers the yield of the lumber as related to defects such as knots, splits, wane, cup, twist, side bend, stain and other issues arising from the processing of the wood and from factors inherent in the wood itself.

The three main grades of lumber are FAS (Firsts and Seconds) / Select and Better, which calls for clear face cuttings (free of defects) of 83 1/3% or better.  This is the top grade, but it is important to note that it is not graded as completely clear.  This grade is used for where long clear cuttings are required for such things as mouldings, windows and doors.

The next grade down is #1C (1 common).  This grade requires a minimum of 66 2/3% - 83% clear face cuttings.  It is primarily used by cabinet and furniture manufacturers that require shorter clear cuttings.

#2C (2 common) consists of 2a and 2b grades.  2a requires 50%-66 1/3% clear cuttings and 2b requires 50%-66 1/3% sound cuttings.  This grade is primarily used by hardwood flooring manufacturers.  There is also a 3c grade, but this a little used grade that only requires 33 1/3% yield.

For the vast majority of hardwood lumber buyers in America the question is not one of grade, but of appearance.  Appearance falls into two categories, clarity and color.    Clarity is the presence or absence of knots, mineral streaks, gum pockets or other natural characteristics.  Color primarily refers to heartwood and/or sapwood content of the wood

Heartwood comes from the center of the log and is the lumber from the part of the tree that was dead before the tree was harvested. Sapwood is the outside, living part of the log when it was cut.  The sought after color (heart or sap) is relative to the species.  In species such as cherry and walnut the more popular color is the heartwood.  In Maple the white sapwood commands a premium price.  In walnut it is common to steam the green lumber to blend heat and sapwood to create a more uniform look.

In addition to appearance the usage and dimensions play a major role in the proper selection of hardwood lumber.  Outdoor applications such as gazebos, siding, decking and lawn furniture require exotic wood such as teak, mahogany, and ipe to withstand the rigors of the elements.  The amount of contact or abuse the final application is going to take can also help determine which type of hardwood to use.  Alder and Cherry work great for kitchen cabinets, but may not be the best choice for commercial hardwood flooring or stair treads due to their relative softness.

The other factor to consider is the dimension of hardwoods needed.  The standard rough (not surfaced) thickness for hardwood lumber is 1”, referred to as 4/4 (pronounced four-quarter).  Each 1/4 refers to a 1/4 inch of thickness.  5/4 = 1 1/4” thick, 6/4 is 1 1/2” thick and so on.  Hardwood lumber is commonly available in 5/4, 6/4, 8/4 and in limited species and quantities 12/4 and 16/4.  Widths are typically random and vary according to specie.

For many buyers dimensional hardwoods are a good choice.  Dimensional hardwoods come ripped to your specified width and are also available as s4s (surfaced four sides).  Dimensional hardwood lumber is more expensive initially because the milling facility has already incurred the waste, but often the consumer saves money when all is said and done due to time and money saved in processing the lumber as well as the risk of miscalculation of how much raw lumber to purchase is alleviated.

Hardwood lumber is measured in 3 dimensional measurement units called board feet. One board foot is the equivalent of 1” (or less) thick x 12” wide x 12” long. Dimensional hardwoods are measured by length only. A 1 x 6 x 12’ board measures 12 lineal feet. There are several good board foot calculators available on-line to help determine amount of board footage required for a project by converting rip sizes into board feet.About the Author: To know more about Hardwood Lumber please browse <a rel="nofollow" href="http://www.woodvendors.com/">Hardwood Lumber</a> , You can also visit <a rel="nofollow" href="http://www.woodvendors.com/">Lumber Company</a> Article Source: <a href='http://www.articleseen.com/Article_Basics-of-Hardwood-Lumber-Grades-and-Characteristics_76864.aspx'> http://www.articleseen.com/Article_Basics of Hardwood Lumber Grades and Characteristics_76864.aspx</a>

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To know more about Hardwood Lumber please browse Hardwood Lumber , You can also visit Lumber Company

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