How do you grade Hardwood Lumber?
Jan 6, 2025
Hardwood Lumber is an essential part of our industry. From Northeastern grown Hard Maple to Appalachian Oak species, we offer an extensive range of domestic Hardwoods for any application. The grade for each Hardwood Lumber board is an integral part of the product, derived from the material defect percentage. Here, the many options for Hardwood Lumber grades are defined.
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Lumber is a living product, responding to its environment as a tree does to its forest. Humidity, age, area and cut will slightly alter the appearance of the lumber product.
Using the National Hardwood Lumber Association (NHLA) Grading standard, Prime Lumber is a premium grade. Developed for the European export market, Prime captures grades within the Select and Better and FAS 1Face and better grades that have been prepared to the highest standard to meet the demands of that market.
Prime grade includes a range of boards with minimum yield from 83 1/3% clear-wood cuttings on the best face. It allows boards 4” and wider before kiln drying and 6’ and longer in length. 6” before kiln drying by 7’ option available.
#1 Common grade is often referred to as the Cabinet Makers Grade because of its adaptability to the standard sizes of kitchen cabinet doors used throughout North America. #1 Common is widely used in the manufacture of furniture parts as well.
#1 Common grade includes boards that are a minimum of 3” wide before kiln drying and 4’ long and will yield a minimum clear face cuttings from 66 2/3% (8/12ths). The smallest clear cuttings allowed in this grade are 3” by 3’ and 4” by 2’. The number of these clear cuttings is determined by the size of the board. Both faces of the board must meet the minimum requirement for #1 Common.
Rustic grade is designed to provide unique character with all its natural defects present. There is no limit on the number of knots, pin knots, bird peck, and mineral streaks. There are often limits on the volume and soundness of pith. These “defects” are all desired in this grade. Rustic is widely used in cabinetry and flooring applications.
The National Hardwoods Lumber Association (NHLA) does not publish any guidelines for “Rustic” grade, making it dependent on individual sawmills and their own production processes. The characteristics present on an individual board are subjective to the agreement between buyer and seller. Rustic Grade boards generally come 4” and wider before kiln drying by 4’ and longer.
Superior Grade delivers the highest quality cuttings available, with a minimum 83.3% clear face on one side. Intended for single face applications, Superior Grade allows for 66.6% clear Cabinet back grade, making the choice of which face to display easy to see. Superior Grade boards come in a range of sizes, permitting a minimum width of 4.5” and minimum length of 6’. This grade is specifically designed to display the beautiful and clear features of Alder and Beech for a dazzling and clear application.
Species-Specific Grades
Alder
CAB is a grade unique to Alder and is specifically designed for two quality face cuttings. CAB Grade Alder allows for boards that are a minimum 4” wide and 6’ long, yielding no less than 66.6% clear two face cuttings. CAB Grade is an excellent choice for applications that display one or two clear faces, such as cabinetry, furniture, and door frames.
Premium Frame Grade is a structurally sound appearance grade. Allowing for small, tight face knots no larger than 0.5” for unsound and 1” for sound in 4” to 5.5”, and 1” unsound and 2” sound knots in boards exceeding 5.5” wide, Premium Frame Grade is a reliable building material. Each cutting is required to yield no less than an 83.33% structurally sound face grade. Cuttings are offered in a range of sizes with a minimum width of 4” and minimum length of 84”.
K-Strip Grade Alder is a sound structural grade, ideal for construction, panels, doors, moldings, and narrower applications. K-Strip allows for face knots with a maximum size of 0.5” for unsound and 1” sound, maintaining robust structural integrity. K-Strip Grade requires a minimum yield of 83.3% Structurally Sound Cuttings, with a minimum width of 4.25” and minimum length of 84”.
European Beech
Cabinet Grade offers a well-balanced mix of long and medium lengths, ideal for usage in cabinetry, drawer fronts and furniture parts for European Beech. Cabinet Grade has a uniform color and is exceptionally cost-effective. Cabinet is graded for two quality face cuttings, yield no less than 66.6% clear cuttings across both faces. Boards are selected with a minimum width of 4” and minimum length of 6’.
Superior 1 Face is the ideal grade for single face applications. The top face of the board is a high yield of clear sapwood, free of knots, burls and mineral streaks with no demands on the back. This is a grade specific to European Beech lumber. Superior 1 Face is sanded smooth for a uniform texture and minimized processing time. An economical product, Superior 1 Face is a popular choice for millworkers and architects alike.
Please consult the UCS Wood Purchasing Handbook for further information on Lumber Grading.
Sources:
NHLA
American Hardwood