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Lumber Glossary

When it comes to wood, there's a lot to know. Learn to talk the talk with our easy to understand glossary of lumber terms, the perfect tool for ensuring you choose the right materials for your next project.


Grade #2 or better


Canadian Softwood Plywood

Dimensional Lumber

Lumber that is finished/planed and cut to a standardized width and depth specified in inches is referred to as dimensional lumber. Solid dimensional lumber typically is only available up to lengths of 24 feet.

Engineered Wood

Composite wood, "man made wood" or "manufactured wood", includes a range of derivative wood products which are manufactured by binding together the strands, particles, fibres, or veneers of wood, together with adhesives, to form composite materials. These products are engineered to precise design specifications which are tested to meet national or international standards

Finger Joint

Solid dimensional lumber lengths are made longer by the technique of "finger-jointing" lumber; using small solid pieces and joining them together using finger-joints and glue to produce additional lengths. Finger-jointing is used predominantly in pre-cut wall studs.


Good on one side


Lumber from deciduous trees which shed their leaves each year such as oak, maple, poplar, gum, walnut, etc. It is used primarily for furniture and flooring. The term does not refer to the physical hardness of the wood; some softwood varieties are actually harder than hardwood.

KD (Kiln Dried)

Lumber that is installed in homes too "wet" will shrink as it dries out causing problems. Therefore lumber will be placed in large temperature controlled buildings called kilns. Heat is added, much like a giant oven, to drive the moisture out faster and more evenly. All kiln dried lumber is dried to a moisture content of less than 19%.


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OSB (Oriented Strand Board)

Wood strands are laid in three or more directionally oriented layers and then bonded together with wax and resins and formed into panels under heat and pressure. OSB is used mainly for roof, wall and floor sheathing and is approximately twice as strong as wafer board, or equal to engineered plywood.


Wood particles (approximately sawdust size) are bonded with resins and formed into panels under heat and pressure. These smooth dimensionally stable panels are used primarily for floor underlayment.


lywood sheets or panels are composed of wood veneer, which is made by rotating logs at high speed against a knife edge. The log is peeled in a continuous sheet of thin veneer. This veneer is then dried and cut into pieces and glued together.


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PT (Pressure Treated)

Lumber that has been treated with a preservative to provide long-term resistance to organisms that cause deterioration. This preservation process generally involves vacuum and pressure treatment. The amount of penetration achieved by the pressure treatment is important as it must be deep enough to treat any cracks, checks or cuts in the wood. When applied correctly, it can extend the productive life of lumber by five to ten times.


Sanded on four sides


Lumber where one or both sides have been filled and sanded. It is used predominantly in projects where appearance is important.


Select Grade or Grade #1


Plywood lumber that has been manufactured and graded for strength and stiffness is commonly called sheathing. It is engineered for use in roof, wall and floor applications.


Wood from coniferous (evergreen) trees such as pine, fir, spruce, hemlock, cedar and larch. This is the most common wood used in construction. The term does not refer to the physical hardness of the wood; some softwood varieties are actually harder than hardwood.

SPF (Spruce, Pine, Fir)

Also known as white woods, these are the most common western softwoods used in construction. They are abundant and possess excellent qualities for building. Since these species have similar characteristics they have been combined into one grade for buying, selling and design standards.


Standard Grade or Grade #2


Studs are pre-cut by the manufacturer to be used in 8', 9' & 10' ceiling applications. Their lengths allow for the height of both the sill plate and the double top plate.

T&G (Tongue and Groove)

T&G is a method of fitting similar objects together, edge to edge. It is used mainly for flooring, parquetry, panelling, and similar constructions. Tongue and groove joints allow two flat pieces to be joined strongly together to make a single flat surface.

Wafer Board

Wood wafers (approximately 3" square) are formed into sheets and bonded with wax and resins under heat and pressure. Wafer size and random orientation result in enough strength to use as roof, wall or floor sheathing