|Every time you look at a board you will automatically give
it a grade. Most times this will be an unconscious process
and you will say to yourself "Wow this is a beautiful board"
or maybe "This board is no good". The following
information will help to put a grade to your observations
Definition of Grades
First and seconds
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.
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
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.
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 Common.
Special Hardwood Grading Considerations
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, Black 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
In Black Walnut graded as Select & Better the minimum cuttings sizes are 4" x 3'
or 3" x 6'.
A board is made up of clear and sound portions and defects. During grading,
the grader visualises 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.
Cutting to Grade
This is a more time consuming proses of specialty cutting in order to produce a
number of types of lumber grades such as quarter sawn, vertical grain or figured
patterns that would not be found in plane sawn lumber.
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.
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.
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.
Definitions of common terms
Book Match 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.
Boards cut with one or more natural edges (live edge).
Boards cut with the natural edge left on, with or without the bark
Distortion of a board lengthwise. A bowed board will not be flat across its length.
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.
Distortion of a board across its width.
Distortion of a board across its width.
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 located.
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.
Discoloration of hardwoods ranging from olive green to brown to black.
Knots up to 1/8" in diameter are considered pin knots. Pin knots in Pine are up
to 1/2" in diameter.
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.
The living portion of the tree extending from the heartwood to the bark. Sapwood
tends to be more pale than heartwood.
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.
Seperation along the grain. It occurs most often between rings of annual growth.
Discoloration in a board. This discoloration is different than sapwood, heartwood
or natural variation. It ranges from pink to gray to brown.
Distortion of a board both lengthwise and/or widthwise.
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.
A term for any variation in the flatness of a board. It can include bow, crook, cup
RGH Rough sawn lumber.
SLR1E Straight line ripped one edge.
SLR2E Straight line ripped two edges.
S2S Surface planed on both sides of the board.
S1S Surface planed on one side of the board.
Resawn A board split in half from a thicker board.
4/4 1" rough thickness.
5/4 1-1/4" rough thickness.
6/4 1-1/2" rough thickness.
8/4 2" rough thickness.
10/4 2-1/2" rough thickness.
12/4 3" rough thickness.
16/4 4" rough thickness.
FAS First and Seconds, the top grade for hardwoods.
Sel&Btr Select & Better. Includes Select & FAS boards.
#1Com Number one common grade.
#2Com Number two common grade.
The lumber grades in this list are the most common grades you will
use. There are many more grades but I will not cover them all on this
I am not able to provide a grading stamp and most lumber graders in
California are prohibited from grading on the side by the mills they work
for. Other States have different polices and you should check with your
sawyer about the regulations in your area. Most of the species of trees in
my area of California do not qualify for structural grading, Douglas Fir is
one of the few trees that do qualify and we don't have many around.
Pine and Cedar do have grades but are not structural grades that can be
used for framing and weight bearing loads. However you do not need
any type of grading stamps for siding, trim cabinets and many other
applications. Building departments vary greatly from county to county on
what they will except as far as ungraded structural lumber. Sometimes
you can sign a waver or they will allow you to oversize structural
members and use them without a grading stamp.
For example: using a 6X6 instead of a 4X4.
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