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Your Complete Guide to Lumber Grades

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Learn more about lumber grades before you purchase lumber.

The average person has only a general idea of lumber, a piece of wood sawn and cut in different sizes for woodworking or property building. However, each wood features various characteristics, including hardiness, appearance, compression strength, and density. Eventually, these factors will define the lumber grades.

Common Defects that Impact Lumber Grades

A piece of wood is stress graded to assess the level of consistency of the final product. The assessment provides an invaluable guide for buyers to manage their expectations. Naturally, higher grades will fetch better prices since the number of defects is relatively low compared to commonly graded products.

The U.S. Department of Commerce supervises the grading of hardwood and softwood lumber. The government also revises the policies and rules covering the industry.

Here are some typical deformities that impact the grades for lumber:

  • Crook — This defect refers to the warping shape of the edge of the lumber. The cause of the deformity could be the location of the pith (the soft core of the tree) or uneven drying.
  • Bow — As opposed to the crook, the bow refers to the curve on the wood’s face. The bend typically extends from one end of the lumber to the other. You can see the arc when the wood is placed flat on the ground.
  • Cup — A cup refers to the concave shape of the wood’s face. If you pour liquid on the material, it will result in a pool of water on the surface.
  • Wane — It’s easy to spot this deformity due to the lack of material at the lumber’s edge. Hardwood lumber grading depends on the amount of wane. The wane results from improper removal of the material by the surfacing machines.
  • Split — The defect refers to the noticeable crack along the face of the wood. The damage can be natural or a result of improper handling. The gap could be large is small, which severely impacts the grade.
  • Shake — The natural defect refers to the natural split in the lumber across the grain. A slight shake won’t affect the grades FAS (first and second), especially if it only appears on one side of the surface.
  • Check — A check can result from the tree’s seasoning, and it refers to the crack on the wood through or across the growth rings. The separation can also be the result of the lumber surface drying up too quickly due to humidity.
  • Knot — As the name suggests, the knot is a concentric deformity on the wood where the tree’s branch broke off. When the trunk is cut into pieces of lumber, these sections will show up as knots. Tight knots should be nothing to worry about regarding structural integrity, but they will affect the lumber grade.
  • Twist — The twist refers to the multiple curves and bends of the wood. Softwood lumber tends to exhibit more twists due to moisture loss. While the twist does not impact the structural integrity of the wood, it is not an ideal material for building unless you are cutting it into smaller pieces.

A lumber company can help explain the different defects and how to select the perfect material for your build.

Lumber Grades According to Dimensions

Dimension grades have multiple levels, and they should serve as a guide for you when estimating costs.

  • Prime Grade – You have the prime grade when the wood features virtually no wanes and is defect-free. Prime grade materials are perfect for framing lumber.
  • No. 1 Grade – The wood attains this classification when the surface contains little knots and wanes. Buyers choose this grade when the final product’s appearance is a significant factor. However, higher grades now refer to prime than this category.
  • No. 2 Grade – The classification refers to wood featuring knots with moderate sizes (also referred to as occasionally sound). It can also have noticeable wane. A No. 2 Grade is sufficient if you are trying to build a wood deck.
  • No. 3 Grade – This construction grading classification is perfect for you when you are not concerned about appearance. The price is relatively low due to the significant amount of wane.

You also have the Dense Grade, branded as Platinum and Premier. You can be assured that the wood features superior tensile properties when you have those classifications. You may find some wane like the No. 1 Grade, but the knots are fewer, and the growth rings are tighter.

Finally, you have the Clear Grade. As the name implies, the wood is free from knots and wanes.

Hardwood vs. Softwood Lumber Grades

As mentioned, there are different grades for hardwood and softwood. But the lumber supply company is not the one assigning the grade.

For instance, the American Hardwood Export Council has a more straightforward process for grading hardwood.

The primary factor for hardwood lumber grading is appearance. The higher grades refer to the number of clear wood products with each cut. Lower grade occurs when more cut is needed to produce clear wood.

The grades FAS determines the highest grades for hardwood. Therefore, they are the best materials for furniture or if the final product is for display.

Meanwhile, American Lumber Standard Committee is responsible for softwood grading, and the appraisal is more complex.

The appearance determines the outcome and whether the lumber is stress graded or non-stress graded.

Stress-graded lumber is perfect if you aim to select structural wood for posts, rafters, beams, and ceiling joints. The capacity to absorb the load is the last determinant for the wood.

Non-stressed grade lumber usually goes for shelving, subflooring, sheathing, and crate construction. The material classification ranges from 1 through 5.

Appearance highlights the overlook of the lumber, considering that the surface might be exposed to the buyer’s eye once installed. The grade classification ranges from A through D for Select and 1 and 2 for Common.

Need Help with Lumber? Peninsular Lumber is Here for You

If you need more information about the lumber grade, call your one-stop shop for lumber, Peninsular Lumber! We have the most extensive collection of building materials to fit your needs. Call our team at 813-875-8805 today, and our friendly personnel is on standby to answer all your questions or visit our lumber company in Tampa Bay today!