DEFINITIONS & GRADES

Board Measure
Board feet is a unit of measure. A single board foot is one foot wide, one foot long and one inch thick or equivalent. For example, a six-inches wide, two feet long and one inch thick is also a board foot. To determine a board surface measure multiply its width in inches by the length in feet and divide by twelve, rounded to the nearest foot. Lumber one inch thick or less are counted at surface measure. If a board is thicker than one inch the, surface measure (board measure of the surface) is multiplied by the thickness, in fractions of an inch, to calculate the true board measure.

Sapwood and Heartwood
Sapwood and heartwood are allowed in any ratio. Any lumber order not specifically mentioning sapwood or heartwood, unless specificed 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. Colour variation may be the result of mineral streaks and spots. Mineral streaks range from olive to brown to black.

Hardwoods

Cutting
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.

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.

Hardwood Grades

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 Common.

#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 structurally sound.

#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

Sap Birch
If sapwood is specified each cutting must have one clear sapwood face. A board surface outside of the required cuttings and the reverse face may be any ratio of heartwood.

Sap Hard Maple
If sapwood is specified each cutting must have one clear sapwood face. A board surface outside of the required cuttings and the reverse face may be any ratio of heartwood.

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.

Walnut, Butternut
In Walnut and Butternut graded as Select&Better the minimum cuttings sizes are 4" x 3' or 3" x 6'.

Pine

Pine Grades

D Select
D Select boards are at least 6' long. These boards have minimal checks and splits. A D Select board may have any one of pitch or knots. Pitch can be no more than 66 2/3% of the face or a single streak. Up to four small, fixed knots are allowed. Shake is allowed only on the reverse face.

Stained Select
Identical in every way to D Select. The only difference is unlimited stain on the face. There is no limitation on the degree of stain.

#1&2 Common
Boards must be 6' and longer. Up to two season checks are admitted. Firm pith up to half the length of the board is allowed. Holes are limited, restricted to pin holes or a single hole. Light stain is allowed only if the board is otherwise of high quality. Stain may cover usually only 33 1/3% of a board unless it is light, very light stain is unlimited. Knots are generally limited in size to about a quarter of the boards width. Red knots can be up to 1/4 " wider than black knots. Boards over 10" wide can have up to 3/4" difference between red and black knots. In either case, the knots must be fixed and sound. There is no limit on the number of knots on a board.

#3 Common
Boards must be longer than 6'. Only a single check is allowed but it can as long as 2' of the face. Pitch is allowed up to half of the boards surface. Pin holes are allowed on the face up to fifteen per square foot. Red knots are allowed up to half the width of the board. Black knots are generally about one third of the board width. Both red and black knots must be sound.

#4 Common
Boards must be longer than 6'. Checks are allowed the full length of the board on the reverse face. There is no limit to pin holes, larger holes are limited to the size restriction of knots. The board may be heavily stained both in colour and coverage. Unsound wood is allowed up to 20% of the face but not extending to any edge. The edges must remain sound. Knots are allowed up to 66 2/3% of the boards width. This includes only firm, fixed knots. Unsound knots and knot holes are limited to 16 2/3% of the boards width. There is no limit to the number of knots on a board.

Hardwood Plywoods

Hardwood Plywood Face Grades

AA Face
The best plywood faces available are graded AA. Colour is most consistent on AA faces, all of the boards are matched for colour. If the face is made up of sapwood veneer then the entire face is sapwood, there is no heartwood. An exception is Knotty Pine, the sapwood and heartwood are mostly indistinguishable. The components are up to 6 ", depending on species, with little to no contrast at the joints. Knots are limited to 1/4" maximum while some species provide for no knots.

A Face
Components of 5" are average across the face with minimal contrast at the joints. Colour matching is close, with almost no sapwood on heartwood faces and almost no heartwood on sapwood faces. Knot allowance up to 1/4" diameter with no repaired knots. Repairs to the veneer are inconspicuous. Bark and work tracks are not admitted but vine marks may be, depending on the species.

B Face
Colour variation is apparent over 4 " components. Sapwood and heartwood are limited but possible on all boards. Knots are admitted up to 1/4" with a single repaired knot up to 1/8". Repairs to the veneer are still inconspicuous but there is no limit on the size of repairs. Mineral streaks are apparent, but limited to 8" at most. Bark is allowed no longer than 1". Vine and worm tracks are visible but limited.

C Face
The lowest grade in most species of plywood. Sapwood and heartwood are mostly unlimited in variation. Colour may vary quite a bit across a sheet. C faces are not available in all species. There is no limit to burls, pin knots, and knots. Repaired knots are limited to a single 3/8" per sheet, 1 1/2" in Knotty Pine. Repairs are overt.

Hardwood Plywood Reverse Face Grades

1 Reverse Face
Colour variation and stain are admitted without limit. Sapwood and heartwood are admitted in any ratio. The reverse face is sound, containing no repaired knots. Splits may be repaired. Knots are allowed up to 3/8 ". The species is identical to the face.

2 Reverse Face
The species is identical to the face. Knots, limited to 3/8" diameter, must be sound or repaired. Sound knots are limited to 3/4" in diameter while repaired knot holes are limited to 3/8" in diameter.

3 Reverse Face
The two faces of a plywood with a 3 back do not necessarily match. Any species is allowed as long as it is solid. Repairs are widespread. Knot holes up to 3/8 " are unlimited but repaired holes can be no larger than 1" across.

4 Reverse Face
The worst reverse face available. It is a reject back, not matching the face species but must be structurally sound. There is no limit to repairs. Bark and ruptured grain do not need to be repaired.

Special Hardwood Plywood Grading Considerations

Ash
Worm tracks are allowed in Ash. In A face graces the work tracks are limited but there is no limit in B faces and lower.

Ash, Birch and Maple
Sheets may be ordered entirely of sapwood, heartwood or natural. Natural boards have no limit on the ratio of sapwood and heartwood. Colour varies widely in natural boards, even in A face grades.

Cherry
Gum spots are admitted in all grades of Cherry. Streaks are admitted in B grade.

Cherry and Walnut
Knot allowances are higher in both Cherry and Walnut. 24 knots are admitted in A grade whereas this limit is admitted in B grade of other species.

Definitions

Book Matching
Plywood components that mirror adjacent components. All components are from the same log with grain matching nearly perfectly along the joints.

Bow
Distortion of a board lengthwise. A bowed board is no longer flat across its length.

Check
A crack in the surface of a board. The crack does not go through the entire thickness of the board. It is a result of uneven drying, particularly by the sun.

Crook
Distortion of a board widthwise. A crooked board is no longer flat across its edge.

Cup
Distortion of a board widthwise. A cupped board is no longer flat across its width.

Heartwood
Heartwood is the dead portion of the tree. It extends from the pith to the sapwood. It is usually a slightly darker shade than sapwood. The centre of the tree holds the heartwood.

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.

Match
The comparison of components on a sheet of plywood. Some boards have unmatched components which may cause variations in colour and grain. Matching includes book, swing and sequence matching.

Mineral Streak
Discoloration of hardwoods ranging from olive green to brown to black.

Pin Knot
Knots upto 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
Seperation 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.

Swing Match
Adjacent components of plywood flipped end-for-end. Knots do not match across a board but stagger.

Twist
Distortion of a board both lengthwise and/or widthwise. A twisted board is no longer flat across its face.

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 collective term for any variation in the flatness of a board. It can include bow, crook, cup and/or twist.