Lumber is wood that’s used for building purposes like framing walls. It’s often affordable and easy to work with.
Lumber is graded for appearance and strength. Stronger lumber gets a higher price and is preferred in DIY projects. Other characteristics to look out for include bow, cup, crook or shake and wane.
What Makes a Piece of Lumber High Quality?
If you ask for a price on a certain type of lumber, the answer will depend on several factors. These include the natural properties of the wood, market demand and how you’ll use it.
Softwood lumber that will be exposed to the elements is often pressure treated with chemicals to preserve it for life. This is especially true for cypress and redwood.
Select appearance lumber is great for visible projects, like shelving and paneling. It has fewer defects than common, tighter knots and is a bit stronger than FAS grade.
Texture
Lumber texture is determined by the size, arrangement and variation of a wood species’s cell walls. Open grained woods typically have coarse textures, while closed grained woods produce fine textures.
The cellular arrangement also determines the appearance of a piece of lumber, such as fiddleback — a wavy, flame-like pattern caused by ray cells — ribbon curl — curving patterns seen in maple and other species, or a silver grain that appears on quarter-sawn oak, which is prized for its sheen.
Color
When it comes to color, some lumber species show more change than others. For instance, Purpleheart is a vivid purple when freshly milled, but mellows to brown in the air and light.
Other woods display figured grain patterns such as curly, wavy or birds-eye. Wood figure doesn’t affect quality, but it does add visual interest. The figured grain is caused by the wood’s growth rings. This is visible as flecks on the surface of the wood.
Lumber Grade
In the United States, softwood lumber is graded by a number of inspection agencies that follow guidelines established by the American Softwood Lumber Standard. Appearance grades such as finish and selects are often nonstress-graded because the emphasis is on appearance and end use rather than strength.
Visually graded dimensional lumber is aggregated into several categories such as structural light framing, structural joists and planks, and stud. The higher the grade, the better quality. Knots must be sound, firm and encased, and there are strict limits on defects.
Splits
A split is a crack or separation in wood usually caused by moisture. It can be a normal characteristic of logs or timbers as they dry, or can occur as a result of damage to the lumber.
Checks and splits occurring in log homes or timbers are generally regarded as a non-structural concern by structural design professionals. This is because they are accounted for in the derivation of design values and handled in lumber grade rules.
Checks
Lumber splitting and checking is a common concern for homeowners and contractors. It is important to understand what checks and splits are, why they happen, and when you need to worry about them.
A wood check is a separation in the fibers lengthwise across growth rings while a wood split is a crack that goes through a piece of timber. Both occur in timbers due to the natural seasoning or drying process. This is especially true for circle sawn timbers.
Shakes
Shakes are separations on the surface of lumber that run parallel to or between the annual growth rings. They can be confined to definite sections, as in cup shake, or they can extend across the entire piece as in ring shake. Although grading rules allow for a certain amount of splits and checks, the presence of shake reduces the resistance of shear stresses in wood members.
Star shake and frost shake propagate from the outside of timbers, following the lines of medullary rays. These cracks weaken the timbers.
Wane
A wane is a missing area on the lumber. Typically this occurs on the end of the board but can run anywhere across it’s length. Often this is the result of bark that remains on a piece of wood after it’s been milled. Regardless, it does not impact durability and can be easily removed by running it through your planer or surfacing machine. This is one of the benefits to purchasing your lumber from a professional woodworking shop.
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