Brief Guide to Lumber and Plywood Grading
(Also See - A Brief Guide to American Hardwoods.)
Most hardwood lumber is sold under the
"quarter" (1/4) system: Four - 1/4" to an
In other words "4/4 rough" equals 1" thick,
5/4 equals 1-1/4" thick, 8/4 equals 2" thick, etc.
BOARD FOOT CALCULATION
Most hardwood is sold by the board foot
(1bf. = 144 cubic inches).
To calculate board feet, multiply length in inches by width
in inches by thickness and divide by 144" (i.e.
96"L x 6"W x I "T = 576" divided by
144" = 4 bf.).
Board footage is calculated on lumber prior to surfacing,
and often prior to drying. Material less than one inch
is tallied by the square foot.
FAS ( First and Seconds)
Provides long, wide, clear cuttings. Best suited for high
quality work. Must yield 83 1/3% to 100% clear wood in
cuttings at least 3" x 7' or 4" to 5'.
Select & Better
Both faces of the board are used in determining the grade.
Best face must meet FAS, reverse must essentially grade No.
No. 1 Common
Provides clear cuttings of medium length and width. Includes
a range of boards which will yield from 66 2/3% to 83 1/3%
clear wood in minimum sized cuttings at least 3" x 3'
or 4" x 2'.
Grading Standards for Hardwood Plywood
Plywood is graded
with a two-character stamp, such as A-1, B2, etc.
The grades reflect the quality of the face veneer
and back veneer respectively.
Here are the descriptions of the ANSI grading
Where excellent appearance is very important as in
cabinets and furniture.
Provide sound surfaces with all openings in the
veneer repaired except for vertical worm holes not
larger than 1/16".
Where the natural characteristics and appearance
of the species are desirable.
Some open defects. Repaired splits, joints, bark
pockets, laps and knotholes can achieve a sound
surface if specified by the buyer.
Provide sound surfaces but allow unlimited color
variation. Repairs in increasing size ranges allowed
respectively from C to D. Applications - where
surface will be hidden or a more natural appearance
Some open defects. Knotholes up to 4" in
diameter are permitted. open splits, and joints
limited by width and length.