Memphis, TN, November 21, 2005--The Wood Flooring Manufacturers Association, also known as NOFMA, has grading rules for comparing like species.
These cover unfinished hardwoods, including oak, beech, birch, hard maple, hickory/pecan and ash as well as factory-finished oak, according to a report in the Orlando Sentinel.
Most species have at least three grades: clear, select and common. Oak, the most common wood flooring, has four: clear, select, No. 1 common and No. 2 common. Clear and select grades, often more expensive and desirable, have more uniform grain patterns, fewer character markings, such as knots and worm holes, and more consistent color.
Wood flooring graded by the association contains either a NOFMA emblem on the bottom of the wood or an American Flooring Manufacturers Association label on the packaging. More information on grades and wood flooring species can be found at www.NOFMA.org.
Here's how the association differentiates between the four grades of unfinished oak:
Clear oak: Mostly heartwood--the oldest, densest and hardest wood of a tree that extends from the center of a log to the edge, or the sapwood--with a minimum number of character marks (knots and milling imperfections) and discoloration so it has a uniform appearance while allowing for natural color variations.
Select oak: Natural heartwood and sapwood with color variations and slight surface imperfections from milling as well as tight knots every 3 inches, pin-worm holes, burls and a reasonable amount of open checks, which are separations of the fiber along the grain.
No. 1 common oak: Prominent variations in color and characteristics, such as flag-worm holes, heavy streaks and checks. Open character marks, such as checks and knotholes, are present but must be sound, which means the wood must be intact. Minor imperfections in machining are permitted. Extremely dark pieces are not included.
No. 2 common oak: Might contain natural variations and manufacturing imperfections as long as they're sound. This grade is for general residential and utility use, and character marks and contrasting appearance are desired.
