Grades

Lumber Grades have been developed over the years to help buyers and sellers, as well as different sawmills across the continent to have the same terms of reference Today when describing the lumber products being traded. In the early days of lumber trading, there was no definitive set of rules when describing the quality required. At times, it may have been as simple as “quality same as the previous shipment”. Today, lumber grades are tailored to the eventually end use of the lumber product whether it be for building house frames, floors, cabinets, or musical instruments.

There are many characteristics of lumber that are taken into consideration when lumber is being graded. An understanding of these characteristics is valuable when consulting the National Lumber Grades Authority (NLGA) Rules when selecting the grade for the end use of the wood being purchased. Some of those characteristics are illustrated here so that the individual grades displayed on each specific lumber page for more clarity.

Bow is a curve along the length of a piece. It is a deviation flatwise from a straight line drawn from one end to the other end of a piece measured at the point of greatest deviation.

Checks are small separations of the wood normally occurring across or through annual rings generally caused by the wood drying to quickly.

Crook is a deviation edgewise from a straight line drawn from end to end of a piece and is measured at the point of greatest distance from the straight line.

Cup is a curve across the width of a piece and is measured at the point of greatest distance from a straight line drawn from edge to edge of the piece. It could be caused by uneven drying causing uneven shrinkage of the two faces or it might be caused in a piece of mixed grain where the vertical grain portion of the piece shrinking less than the flat grain on another portion of the piece

There are different types on Knots that are considered when grading lumber. These include the following:

Black Tight Knot

Black Loose Knot

Checked Knot

Encased Knot

Unsound Knot

Knot Hole

Slough Knot Hole

Spike Knot

Shakes are lengthwise separations of the wood which develop in a standing tree and usually occurs between or through the annual rings

Spit is a lengthwise separation of the wood due to the tearing apart of the wood cells. It is commonly caused by severe checking on the ends or by pressure in the planer caused by a board with cup

Wane wood from any is bark or lack of wood on the edge or corner of a piece of lumber.

The Lumber Grades included on this site are not all encompassing.

There are additional grades specified in the NLGA Standard Grading Rules for Canadian Lumber that are intended for more specific end uses or that are meant for further reworking. Detailed information on the lumber grades that we have not included here can be obtained either directly from NLGA or by request through our Contact Us page.

Missing or redundant grades include:

Clear Panelling – All Species (Except Western Red Cedar) may be used for panelling and are graded under the Finish Rules, except that it is graded on one face.

Window Jamb, Door Jamb, Door Sill, Window Sill, Window Stool patterns are to be graded under the Finish Rules, except that they are graded on one face.

Eastern White Pine and Red Pine Boards

Machine Graded Lumber – All Species:

Machine Stress Rated (MSR)

Machine Evaluated Lumber (MEL)

E-Lam Lumber

Glued Lumber – All Species

Specialty Items – All Species:

Ladder Rails

Gutter

Mast, Spar, and Boat Lumber

Flitches for Remanufacturing – All Species

Moulding Stock – All Species

Window Stock – All Species

Factory Lumber and Door Stock:

Stiles, Rails, Top Rails, Narrow Lock Rails and Muntins – All Species

Pine Furniture Grades

Railway and Car Material Grades – All Species

Scaffold Planks – All Species

Structural Laminations

Pickets

Lath

Pipe Stave Stock (Douglas Fir)

Silo Staves (Douglas Fir)

CrossArms (Hen-Fir)

Tank Stock (Douglas Fir, Western Red Cedar, Yellow Cedar)

Stadium Stock (Yellow Cedar)

Structural Laminations (Douglas Fir)

Page updated

Google Sites

Report abuse