Draft_Furniture Essentials_SP_9-3-16- v.1

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Types of Wood

Furniture Essentials

The Basics of Hardwood Lumber Grades The National Hardwood Lumber Association (NHLA) grades are based on the percentage of clear-defect free wood on a board. A defect is a irregularity occurring in or on wood that reduces its strength, durability, or usefulness. Some common defects are: 1. Knots - embedded limb or branch of the tree. It reduces the strength but might im- prove the appearance. 2. Splits/Checks - a seperation of the wood along the grain and across the grain. 3. Wane - the presence of bark or absence of wood along the edge of the board.

The measurement of this percentage are referred to as clear-cuttings.

The NHLA grades are determined on an imperial measurement system using inches and feet. A board foot is the unit of measurement. The best grade is the FAS (First and Seconds). This piece of wood cannot be less than 6 in. wide by 8ft. Long and yield at least 83 1/3 percent clear

B.F: one foot long, one foot wide, one inch thick

To determine the board feet in a board:

Multiply the width in inches by the length in feet and divide by 12. If the lumber is thicker than one inch, multiply by the thickness.