Board feet is
a unit of measure. A single board foot is one foot wide, one foot long
and one inch thick or equivalent. To determine a board footage,
multiply its width in inches by the length in inches and by its
thickness in inches and divide by 144. This will give you the total
board footage in a piece of lumber.
Sapwood and Heartwood Sapwood and heartwood are allowed in any
ratio. Any lumber order not specifically mentioning sapwood or
heartwood, unless specified by a particular grade, may have any amount
of heartwood and sapwood. For example, a board entirely of heartwood,
a board entirely of sapwood and a board half of each are identical.
Stain Unless a grade specifically mentions stain, no stain is
admitted in surfaced stock. If stain is admitted in a grading, the
stain cannot change the hardness of the wood.
Streaks and Spots Mineral streaks and spots are admitted. Color
variation may be the result of mineral streaks and spots. Mineral
streaks range from olive to brown to black.
Cutting A board is made up of clear and sound portions and
defects. During grading, the grader visualizes the maximum clear yield
of a board. A portion of a board's surface that is clear is measured.
The sum of each of these clear portions is tallied and used towards
grading a board. A clear portion is an imaginary rectangle extended as
far as possible between defects. For example, a clear portion, a clear
cut, is bordered by four knots or four edges or a combination thereof.
A clear cut may be bordered by two knots and two edges. The remaining
surface area of a board that is not classified as clear may be either
sound or defect.
Clear Face Cutting A cutting with no defects is classified as a
clear face cutting. The reverse face must be sound for a clear face
grading. If the back is worse than sound the face is not classified as
clear. For example, a board with no defects on its face cannot be
classified as clear if the back is riddled with unsound knots. The
clear face grading relies on the back to be sound.
Sound Cutting A sound cutting is a board that is free of rot,
pith, shake and wane. A board is sound if it contains sound knots,
bird pecks, stain and streaks. Soundness means the board's strength is
not impaired by anything on its surface. Holes are admitted in a sound
board, unless they are the entire thickness of the board, up to two
1/4" holes or one 1/2" hole per 12 cutting units.
Cutting Units A cutting unit is an imaginary rectangle
one inch wide by a foot long, exactly 1/12th of a board foot. Cutting
units are used to determine the extent of surface features on a board
during grading. A grader cuts the board in their imagination;
different grades allow a minimum number of cutting units. For example,
a board 9 3/8" wide by 16' long contains defects. A clear portion
8 1/2" x 6' yields 51 cutting units, a 3" x 9 1/2' portion
yields 28 1/2, 4" x 2 3/4' yields 11 and 3" x 3 1/3' yields
10. The sum of the cutting units is 100 1/2, about 67% of the board. A
board containing 67% clear cutting units is at best #1 Common. A board
would never be cut this many times; it is just a method to calculate
the clear portions of the board.
FAS An FAS board must be at least 6" wide and 8'
long. 83 1/3% of the board must be clear. To determine cutting units
the maximum number of imaginary cuts is one-quarter of the board
measure. For example, a 6" x 8' board is 4 board measure. The
board can be cut only once, 1/4th of 4. After this single imaginary
cut the board must be 83 1/3% clear. The area of each imaginary cut
must leave at least 4" x 5' or 3" x 7' sections. If a board
is 8 board measure then two cuts are allowed, yielding 83 1/3% clear,
each cut at least 4" x 5' or 3" x 7'. If a single cut in a
6" x 8' board does not yield an FAS grade there are additional
rules. One additional cut is allowed in boards between 6 and 15 board
measure if the resulting clear portion of the board is 91 2/3%. The
reverse face of a board must also be FAS for the entire board to be
graded as FAS.
F1F (FAS One Face) If a board face is graded to FAS but the
reverse face is not, the board drops in grade. If the reverse face of
a board can be graded as #1 Common, the entire board is graded as F1F.
For example, if a board face grades to FAS but the reverse face only
yields 82% clear the entire board is graded to at best F1F. If a board
reverse face cannot be graded to #1 Common the board is not F1F.
Select A select board is graded exactly like FAS. The only
difference is that the minimum size of a Select board is 4" x 6'
(whereas an FAS board must be at least 6" x 8'). The reverse face
of a Select board can be either Select or #1 Common.
#1 Common A #1 Common board must be at least 3" wide and
4' long. 66 2/3% of the board must be clear. The maximum number of
imaginary cuts is one-third of the board measure plus one. Surface
area after each imaginary cut must be at least 4" x 2' or 3"
x 3'. For example, a board 6" x 8' is 4 board measure. One third
of 4 + 1 is 1. If a single imaginary cut in the board yields 66 2/3%
clear where the uncut area is at least 4" x 2' or 3" x 3',
the board is graded as #1 Common. An additional cut in the board is
allowed if the resulting clear yield is at least 75%. This applies to
boards between 3 and 10 board measure. The reverse face of a #1 Common
board is always #1 Common.
#2 Common A #2 Common board must be at least 3" wide and
4' long, just like #1 Common. The clear yield of a board can be as low
as 50% after cuts equal to half of the board measure. Surface area
after each imaginary cut must be at least 3" x 2'. For example, a
board 6" x 8 is 4 board measure and can be cut twice, half of
four. The resulting clear area of the board must be at least 3" x
2' and at least 50% clear. An additional cut is allowed in boards
between 2 and 7 board measure if the yield is 66 2/3% clear. The
reverse face of a #2 Common board can be #2 Common or better. If the
reverse face of a board is #3 Common then the entire board becomes #3
#3A Common #3A Common boards must be at least 3" x 4' but
yield as much as 33 1/3% clear. There are unlimited imaginary cuts as
long as the resulting uncut area is 3" x 2'. A board may be
graded as #3A Common if the face is #2 Common and the reverse face is
#3B Common Boards at least 3" wide and 4' long with 25%
clear are classified as #3B Common. There are an unlimited number of
imaginary cuts with the resulting area at least 36 square inches no
narrower than 1 1/2".
Special Hardwood Grading Considerations
Cherry An unlimited number of pin knots are allowed in
all grades of cherry. Each knot must be sound and no larger than
1/8" in diameter. Gum spots and streaks are also admitted in any
grade without limit.
Red Oak, White Oak Mineral streaks and spots, and streaks and
spots of a similar nature, are allowed in cuttings. The total area of
these streaks and spots can be no more than 8 1/3% of cuttings.
Streaks and spots outside of the cuttings are allowed to any degree.
Poplar Mineral is allowed in cuttings of Poplar up to 16 2/3%
of cuttings. The limit of 16 2/3% is limited to FAS, F1F and Select
faces. Faces graded #1 Common or lower there is no limit to the amount
of mineral in cuttings.
Black Walnut, Butternut In Black Walnut and Butternut graded as
Select&Better the minimum cuttings sizes are 4" x 3' or
3" x 6'.
Book Matching Bookmatch is a set of boards that mirror
one another. They have been cut from a single log and the two faces
match in grain pattern and color.
Bow Distortion of a board lengthwise. A bowed board will not be
flat across its length.
Check A crack in the surface of a board. The check does not go
through the entire thickness of the board. It is a result of uneven
drying, particularly by the sun, and many times from too aggressive
kiln drying schedule.
Crook Distortion of a board across its width.
Cup Distortion of a board across its width.
Heartwood Heartwood is the dead portion of the tree. It extends
from the pith (center) to the sapwood. It is usually a slightly darker
shade than sapwood. The center of the tree is where the heartwood is
Knot Discolored wood resulting from a branch. Red knots are
living branches which the tree has overgrown. In Pine, red knots are
usually sound and fixed since it grew until the tree was cut down.
Black knots are dead wood, from dead branches, which are not
necessarily fixed. Fixed knots are those which will only fall out of a
board when under direct pressure.
Mineral Streak Discoloration of hardwoods ranging from olive
green to brown to black.
Pin Knot Knots up to 1/8" in diameter are considered pin
knots. Pin knots in Pine are up to 1/2" in diameter.
Pith A portion of wood usually softer than the surrounding
board. It occurs more often in heartwood at the center of trees. Pith
that is equal hardness to the surrounding board is not a defect.
Sapwood The living portion of the tree extending from the
heartwood to the bark. Sapwood tends to be more pale than heartwood.
Sequence Match Adjacent components of plywood are of lateral
layers from the same log. Features are nearly identical across a sheet
with grain lining up almost perfectly.
Shake Separation along the grain. It occurs most often between
rings of annual growth.
Stain Discoloration in a board. This discoloration is different
than sapwood, heartwood or natural variation. It ranges from pink to
gray to brown.
Twist Distortion of a board both lengthwise and/or widthwise.
Wane A lack of wood on the edge of a board. Wane may include
bark. Wane is the result of a board being cut too close to the outside
of a tree.
Warp A term for any variation in the flatness of a board. It
can include bow, crook, cup and/or twist.