The world of lumber has its own unique language and terminology, which can make it confusing if you’re just beginning to get into carpentry. But don’t let the jargon throw you off of your DIY game. This comprehensive guide to lumber terms covers wood types, dimensions, grades, and everything else you need to know about wood. By the end, you’ll be equipped with the knowledge to select the right lumber for your needs.
Types of Wood: Softwood vs. Hardwood
Wood is generally classified into two main categories: softwood and hardwood. Despite their names, these classifications don’t necessarily indicate the wood’s hardness. Some softwoods can be harder than certain hardwoods, so the terms can be somewhat misleading. Instead, they refer to the type of tree the wood comes from and its cellular structure.
Softwood Characteristics and Uses
Softwood comes from coniferous trees, such as pine, spruce, and fir, which typically have needle-like leaves and produce cones. Compared to hardwoods, softwoods are generally less dense, lighter in color, more readily available, less expensive, and have a straight grain pattern. These differences make them a popular choice for framing houses and buildings, furniture making, and outdoor projects, such as decks and fences.
Hardwood Characteristics and Uses
Hardwood comes from deciduous trees, including oak, maple, birch, and walnut, which lose their leaves annually. Hardwoods tend to have more complex grain patterns and come in a wider range of colors compared to softwoods. It’s often used for cabinetry, decorative woodwork like moldings, flooring, and high-end furniture.
Decoding Lumber Dimensions
One of the most confusing aspects of lumber for beginners is understanding dimensions. The size you see on a lumber tag may not match what you measure with your tape.
Nominal vs. Actual Dimensions
Nominal dimensions are the “nickname” sizes used in the lumber industry. For softwoods, these dimensions give thickness and width, such as two-by-four (“2×4”) or one-by-eight (“1×8”). Hardwood dimensions typically only give thickness, expressed as a fraction over four, including 4/4 (“four-quarter”) for 1 inch or 12/4 for 3 inches.
Actual dimensions are always smaller than nominal dimensions. For example, a two-by-four is actually about 1 1/2 inches by 3 1/2 inches. This difference is due to the milling process and has become standard in the industry. When planning your project, always use actual dimensions for accurate measurements.
Board Feet
Board feet is a unit of measurement used to price exotic and other woods not milled to standard sizes. One board foot equals 144 cubic inches of wood, or a piece of wood 1 inch thick, 12 inches wide, and 12 inches long. This measurement should be used when purchasing hardwoods or custom-cut lumber for specific projects.
Common Lumber Grades and Their Meanings
Lumber grading helps categorize wood based on its quality and appearance and can dictate the best lumber for your project.
Hardwood Grades
Hardwood grades are based on the number and size of clear areas (areas free from defects) on the board. The grades are defined by the National Hardwood Lumber Association (NHLA), and common ones include:
- First and Second (FAS) is the highest grade and is 83.34% defect-free over its entire surface. There will be little variation in color. It must be at least 6 inches by 8 feet.
- FAS One Face (F1F) needs to be 83.34% defect-free on its best side and meet the standards of Number 1 Common on its other side. It must also be at least 6 inches by 8 feet.
- Select is similar to F1F, but the board only has to be 4 inches by 6 feet.
- Number 1 Common (No. 1C) are good-quality boards, but they only have to be at least 66.67% defect-free. They’re often called “cabinet grade,” and have to be at least 3 inches by 3 feet or 4 inches by 2 feet.
- Number 2A Common (No. 2AC) boards, often called economy grade, allow for more defects—they only have to be 50% defect free. They need to be at least 3 inches by 4 feet.
- Number 2B Common (No. 2BC) has similar requirements to No. 2AC, but as stated in the American Hardwood Export Council’s guide, “all required cuttings are only required to be sound.”
Softwood Grades
Softwood lumber is graded according to the American Softwood Lumber Standard and the U.S. Department of Commerce. Softwood is broken down into two categories: construction and remanufacture. Most softwood available for purchase falls into the construction category, which can then be further divided into stress-graded, non-stress-graded, and appearance.
Non-Stress Graded Lumber
Non-stress-graded lumber is the most common. These boards need to be structurally sound, but they’re also graded on appearance. There are five grades under this category:
- Construction: Also known as No. 1, these have moderately sized tight knots. It’s ideal for painting and is often found in siding, shelving, and furniture.
- Standard: These boards, also referred to as No. 2, will have more knots than Construction. While it may not accept paint as well as Construction, it’s often used for similar projects.
- Utility: In No. 3 boards, there will be several knots and splits. These tend to be used for crates and small furniture parts.
- Economy: Economy boards will have many more defects and are usually used for subflooring and similar projects. No. 4 Economy can take paint, but not well. However, No. 5 Economy can’t be painted.
Appearance Graded
Appearance graded softwoods take the look of the wood into account first and structural integrity second. These grades can get confusing as there are different grades for different types of wood species.
There are two main grades for Appearance: finish grade and select grade. Finish grade is the highest quality, but most homeowners and woodworkers will come across Select more often for their projects.
Select includes these grades:
- A boards have no defects and are used for fine pieces and projects.
- B boards can have slight defects, but are used in the same projects as A.
- C boards may have small knots, and tend to have a best side. They can be used for most furniture pieces.
- D boards have more defects, but they’re still used in some furniture projects.
Stress-Graded
Stress-graded construction lumber is usually used for posts, beams, decks, timbers, and other situations where stress on the lumber occurs. These pieces are rated on stiffness, structural integrity, and uniformity. The exact grade used depends on the size of the board and the wood type.
Specialized Lumber Types
Beyond standard lumber, there are specialized types designed for specific uses or to enhance wood properties, including pressure-treated lumber and engineered wood.
Pressure-Treated Lumber
Pressure-treated lumber is wood that has been treated with chemical preservatives to resist rot, decay, and insect infestation, making it ideal for outdoor projects and ground contact applications.
There are different types of treated lumber, each with specific uses. For projects in the home, you’ll likely run into above ground lumber, which should be used in projects that will never come into direct contact with soul, or ground contact, which can be used on the ground and can come in contact with freshwater environments.
Engineered Wood
Engineered wood is manufactured by binding wood fibers, veneers, or strands together with adhesives. These products offer consistent quality and are a very common building material. They are particularly popular in flooring, cabinetry, and construction applications, offering reliability and ease of use.
Common types of engineered wood include:
- Plywood: Made from thin layers of wood veneer
- Medium Density Fiberboard (MDF): Made from wood fibers compressed with resin
- Oriented Strand Board (OSB): Made from wood strands arranged in layers
- Laminated Veneer Lumber (LVL): Made from thin wood veneers bonded together
Lumber Seasoning Methods
Seasoning is the process of drying lumber to reduce its moisture content, making it more stable and less likely to warp or shrink. There are several methods of seasoning lumber:
Kiln Dried Lumber
Kiln drying is a controlled process where lumber is dried in a large oven-like chamber. This method allows for precise control of temperature and humidity, resulting in lumber with a consistent moisture content. Kiln dried lumber is less likely to warp or shrink after installation.
Air-Dried Lumber
Air drying is a natural seasoning method where lumber is stacked outdoors and allowed to dry naturally. This process can take several months to a year, depending on the wood species and local climate. Air-dried lumber may retain more of its natural characteristics but can be less consistent in moisture content.
Heat Treated Lumber
Heat treating involves heating the wood to a specific core temperature to kill insects and their eggs. This process is often used for lumber intended for international shipping to prevent the spread of pests.
Lumber Abbreviations and Markings
Lumber often comes with various stamps and markings that provide important information about its grade, moisture content, quality, and treatment. Some abbreviations you might see include:
- AD: Air-dried
- HT: Heat treated
- KD: Kiln dried
- MC: Moisture content
- PT: Pressure-treated
- S4S: Surfaced four sides
- SPF: Spruce-Pine-Fir (a common lumber grouping)
How to Read a Lumber Quote
Reading a lumber quote correctly is necessary for budgeting and ordering materials. A typical lumber quote will include:
- Dimensions (nominal and sometimes actual)
- Grade
- Price per unit
- Quantity (often in board feet for hardwoods or piece count for dimensional lumber)
- Total price
- Wood species
When reading a quote, pay attention to whether the dimensions are nominal or actual, and make sure you understand the grading system being used. Don’t hesitate to ask for clarification if any part of the quote is unclear.
Sustainable Lumber Practices
Sustainability is an important consideration when selecting lumber. Sustainable lumber practices make sure that forests are managed responsibly, preserving ecosystems and minimizing environmental impact. Various certifications and initiatives help promote sustainable forestry, making it easier for consumers to choose environmentally friendly options.
Forest Stewardship Council (FSC) Certification
The Forest Stewardship Council (FSC) is a global organization that certifies responsibly managed forests. Lumber that is FSC-certified comes from forests that prioritize environmental conservation, social responsibility, and economic viability.
Alternative Sustainable Wood Sources
There are also alternative sustainable wood sources that can reduce reliance on traditional lumber. Bamboo, for example, is a rapidly renewable resource that can be used in various woodworking and construction applications. Reclaimed wood is another sustainable option as repurposed old wood from buildings, barns, and other structures can be used for new projects.
Tips for Choosing the Right Lumber
Selecting the right lumber for your project involves understanding the specific needs and requirements of the task at hand. Here are some tips to help you make the best choice:
- Know your project’s requirements: Identify the specific characteristics needed, such as strength, appearance, and durability.
- Understand wood species: Different wood species have varying properties. Research the wood type best suited for your project.
- Inspect lumber quality: Look for defects, such as knots, warping, and splits. High-quality lumber will have fewer defects.
- Consider moisture content: Make sure the lumber has been properly seasoned to avoid issues with warping and shrinking.
- Check sustainability certifications: Choose lumber with sustainability certifications to support responsible forestry practices.
Our Conclusion
By familiarizing yourself with wood types, dimensions, grades, and specialized products, you can make informed decisions about the lumber you use in your projects. While this guide provides a comprehensive overview, lumber standards can vary by region and supplier. Always consult with the knowledgeable staff at your local lumber yard or home improvement store if you have specific questions about your project needs.