When many of us think about lumber, we think of uniform planks of wood, separated by wood type. However, the process of milling felled trees into the lumber we recognize today is much more complicated than simply sorting felled trees by type. In fact, there’s a process called grading that helps to categorize wood into much more than just species or appearance.
In this guide, we’ll break down the basics of lumber grading, helping you understand how the quality of lumber influences the quality of solid wood furniture.
What Is Lumber Grading?
Lumber grading is the process of categorizing wood based on its quality and strength. The grade of lumber indicates its structural integrity and appearance, which are critical factors in determining its best use moving forward. Grading is typically done by visual inspection, although there are more precise methods, like machine stress rating, used for certain applications.
Why Is Lumber Grading Important?
Selecting the correct grade of lumber for your project ensures safety, durability, and longevity over time. For example, high-grade lumber is ideal for structural components, where strength is the most important quality, while lower-grade lumber might be best used for non-structural applications.
Lumber Grading Basics
1. Softwood Lumber Grading
Softwood lumber, commonly used in construction, is graded by the American Lumber Standard Committee (ALSC) based on visual inspection. Here’s a quick rundown of the main softwood grades:
- Select Structural (SS): This is the highest grade, offering the best combination of strength and appearance. It’s often used in critical structural applications where both aesthetics and strength are important.
- No. 1 and No. 2: These grades are slightly lower than Select Structural. No. 1 is still very strong and often used in load-bearing structures, while No. 2 may have more knots or imperfections, making it suitable for something like framing.
- No. 3 (Utility): This grade has more defects and is typically used where strength is less critical, such as in temporary structures or for non-load-bearing walls.
- Construction Grade: This is a broad category that includes No. 1 and No. 2 grades but is specifically marked for general construction purposes.
2. Hardwood Lumber Grading
Hardwood lumber is typically used for furniture, flooring, and cabinetry. The National Hardwood Lumber Association (NHLA) governs hardwood grading, focusing on the usable wood yield from a board.
- FAS (Firsts and Seconds): This is the highest grade of hardwood, offering a high percentage of clear, defect-free wood. It’s ideal for fine furniture and cabinetry because it provides large, clean pieces of wood that’s both strong and aesthetically pleasing.
- Select: Slightly lower in quality than FAS, Select grade lumber may have more knots or imperfections, but it still offers good yield and is suitable for most furniture projects.
- No. 1 Common and No. 2 Common: These grades allow for more defects, such as knots and cracks. They’re often used in less visible parts of furniture or in applications where the appearance of the wood is not as critical.
Factors Affecting Lumber Grades
Several factors influence the grade of lumber, including:
- Knots: Knots are natural imperfections in the wood where branches were once connected to the tree. The size, location, and frequency of knots impact the wood’s strength and grade.
- Grain: The straightness, tightness, and evenness of the grain affect both the strength and aesthetic appeal of the lumber.
- Splits and Checks: These are cracks in the wood that occur during drying. Large or numerous splits can weaken the wood and lower its grade.
- Wane: This is the presence of bark or the absence of wood along the edge of a board. Wane reduces the usable portion of the wood and can lower its grade.
Understanding Lumber Grade Stamps
When purchasing lumber, you’ll often see grade stamps on the wood. These stamps provide key information about the wood, including:
- Mill Identification: The mill that produced the lumber is often identified by a number or name.
- Grade: The grade of the lumber is clearly marked, such as No. 2 or Select Structural.
- Species: The type of wood is often indicated by an abbreviation, like DF for Douglas Fir or SPF for Spruce-Pine-Fir.
- Moisture Content: The stamp may also indicate whether the wood is kiln-dried (KD) or air-dried (AD). Moisture content is important because it affects the wood’s stability, strength, and resistance to warping or shrinking after installation.
How Lumber Grade Affects Solid Wood Furniture
So, why is the grade of lumber used to build furniture important?
Overall, the grade of lumber plays a role in the quality, appearance, and longevity of solid wood furniture. Higher-grade lumber, such as FAS (Firsts and Seconds) or Select, offers a greater yield of clear, defect-free wood– ideal for visible surfaces like tabletops, chair legs, and cabinetry fronts. These grades make sure that your furniture has a smooth, uniform appearance with minimal knots, warping, or imperfections.
On the other hand, using lower-grade lumber can introduce more natural variations and character into the piece, such as knots and grain irregularities. While these imperfections add a sense of uniqueness or charm to a piece, they may also require more careful selection and cutting to make sure the piece is visually pleasing.
At Vermont Woods Studios, the local craftsmen we partner with are able to source the highest-grade lumber to create the heirloom pieces you know and love. This is because unlike larger manufacturers that can’t source the highest quality of wood due to the large quantity needed, the Vermont craftsmen we work with are able to carefully select smaller, premium batches of wood.
For solid wood furniture crafted from the highest quality wood, be sure to take a look at our collection of hand-crafted wood furniture built to the highest standards of quality, longevity, and beauty.