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Types of Lumber

When it comes to buying lumber, there are a lot of choices to make. Choosing lumber means understanding grain patterns, grades, types of wood and more. Which type of lumber you end up using for a project depends on its purpose. 

For structural needs such as joists or beams, the look of the lumber isn’t a top priority. However, if the wood is going to be visible, you may want a higher grade of lumber. Use this guide to learn lumber terms, measurements and grades so you can understand how to choose the right lumber for your next project. 


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Whether you are taking on a smaller DIY project like shiplapping a bedroom wall, or you're tackling a big job like new construction, these common terms will help you determine to how to choose lumber. 

Lumber Features

  • Texture is the feel and condition of the wood’s surface. Wood’s texture is a key part of its stability and its ability to be finished or stained.
  • The color of wood determines the look and style of your project. If the wood won’t be visible, as in the case of a structural project, color won’t matter much to your selection process.
  • Density is a wood’s weight and strength. The denser the wood, the sturdier the result of your project. This is why the best wood for structural or supporting projects such as beams tends to be denser.
  • Grain is a tree’s unique growth pattern. No two boards will look the same. It’s important to consider grain when working on projects, specifically decor, to ensure you achieve the look you want. Aesthetic appeal matters most if the wood of your project will be visible.

Hardwood vs. Softwood

There are two categories of wood: hardwood and softwood. The lumber industry uses a scale called the Janka Rating System to measure and rank the relative hardness of wood. Hickory is the hardest, commercially available common wood. Next in line are pecan, hard maple and white oak.

Hardwood includes wood like hickory, oak, mahogany, maple and walnut. If you’re unsure what wood you’re working with, perform a quick test by pressing your fingernail into the wood. If it is  hardwood, it will not dent easily. The types of hardwood you choose will ultimately depend on your project and the look you are trying to achieve. Typically used in cabinetry, flooring and woodworking. Usually requires more upfront investment than softwood.

Lumber Types

While terms like boards, studs and plywood all refer to types of lumber, they should not be used interchangeably. Each type of lumber is designed to be used for specific building purposes. Read on for a breakdown of the most commonly used types of wood as well as their features and benefits. 

Framing and Structural Lumber

The most commonly used lumber, structural lumber, are the 2-foot x 4-foot and 4-foot x 4-foot boards used in everyday DIY and construction projects.

Framing and structural lumber follows standard building dimensions (thickness and width). Standard dimensions allow for faster building as less cutting is needed on site.

Structural lumber can be broken down into seven categories:

  • Light framing lumber is 2-inches to 4-inches thick and 4-inches wide.
  • Structural light framing is 2-inches to 4-inches thick and 2-inches to 4-inches wide.
  • Dimensional lumber and studs are 2-inches to 4-inches thick and 2-inches to 4-inches wide.
  • Structural joists and planks are 2-inches to 4-inches thick and 6-inches wide.
  • Beams and stringers are at least 5-inches wide and 2-inches thick.
  • Posts and timbers are usually 5-inch x 5-inch boards.
  • Appearance framing lumber is 2-inches wide and 1-inch thick.

Appearance Boards

Appearance boards are chosen primarily based on how they look rather than their strength. They must be at least 1-inch thick and 2-inches wide. There are two grades of appearance boards, “Finish” (a higher grade) and “Select”. Appearance boards are ideal for shiplap projects, DIY crafts, interior furniture and decor.

Appearance boards can be used untreated or painted/stained. They are available in hardwoods, softwoods, reclaimed wood and barn wood boards.


Plywood is made from layers of thin sheets of wood and cured under heat and pressure. It’s ideal for DIY crafts, shelving and subfloors. Plywood can be used untreated, painted or stained. It’s available in hardwood and softwood veneers.


MDF, or Medium-Density Fiberboard, is a combination of hardwood and softwood bound with resin. It’s denser than plywood but is not very moisture resistant. MDF is ideal for the unseen parts of cabinets, interior furniture or shelving.

Decking and Fencing

Deck and fencing lumber includes railings, floor boards, posts and balusters. It is available with above-ground contact or ground contact treatment.

  • Composite deck lumber is made of a combination of wood and plastic, making it dense and durable.
  • Wood decking boards are durable and budget-friendly.
  • Composite decking boards are available in a range of colors and won’t warp or crack.
  • Deck tiles create custom patterns on deck surfaces with an interlocking tile system.

Pressure-Treated and Untreated Lumber

Pressure-treated lumber is wood that has been processed with preservatives to last longer. It is available with above-ground contact or ground contact treatment.

  • Choose from wood decking boards, composite decking boards and deck tiles.
  • Wood decking boards are durable and budget-friendly.
  • Composite decking boards are available in a range of colors and won’t warp or crack.
  • Great for exterior use and projects that come in contact with cement. It is rot-resistant and can be painted or stained easily.
  • Heavier than untreated lumber, so it tends to require more upfront investment.
  • Many of the chemicals used in pressure treating lumber contain pesticides.

Untreated lumber is great for projects involving animals, children or plants. Some types of lumber, like cypress and redwood, are naturally rot-resistant. Untreated lumber is also lighter, easier to cut and budget-friendly. 

Lumber Grades

Grade refers to both the appearance and strength of the lumber. Hardwood and softwood have their own grading systems. Lumber grading determines both price and how the wood will be used. Strong lumber with fewer knots or cosmetic blemishes gets a higher grade and price. Some types of lumber may be marked as “premium” by the manufacturer, but this is not a standard grade. “Premium” refers to the clean appearance of the board but doesn’t verify the strength or physical quality.


Hardwood is graded by the National Hardwood Lumber Association. Hardwood grades are:

  • FAS (First and Second) is the highest grade of hardwood lumber. It’s usually 6-inches x 8-inches and is 83 percent defect-free on its best side.
  • Select is 4-inches x 6-inches and 83 percent defect free on its best side.
  • No. 1 Common is 3-inches x 4-inches and 66 perfect defect free on its best side.
  • No. 2 Common is 3-inches x 4-inches and 50 percent defect free on its best side.

Softwood grades typically fall into two categories: dimensional lumber (based on the wood’s strength) and appearance boards (most commonly used for woodwork).

  • C Select has little to no defects and is used for cabinets and trim.
  • D Select has a few more defects than C select. It’s great for projects that will be painted.
  • No. 1 Common is a standard grade lumber with a knotty look.
  • No. 2 Common has larger knots. It’s good for paneling and shelving.
  • No. 3 Common has larger knots than No. 2 Common. It’s best for shelving, paneling, pallets and fences. 

Tip: If “prime” is listed with the grade, such as “prime FAS grade,” the lumber has both the qualities of the FAS grade and a fine appearance. Search for prime lumber when the look of the wood is particularly important for a project. 

Lumber Measurements

Lumber is identified by its nominal or named size. The nominal size is the lumber’s rough dimension before it is trimmed to its finished size at the lumber mill. This is the size that appears on the tag in store. Actual lumber sizes are approximate dimensions after trimming. 

For example, for the dimensions of lumber, a tag that says “2-inches x 4-inches” doesn’t actually mean lumber that’s two inches by four inches in measure. Rather “2-inches x 4-inches” is in actuality 1-1/2-inches x 3-1/2-inches.

Nominal size is usually the size quoted in DIY project instructions. If actual lumber sizes are required, that will be noted. These measurements clarify what you’ll see on the tag in stores (nominal size) versus the actual measurements of the lumber (actual size).

Common Lumber Defects

All wood has natural defects that can add character. There are, however, some defects in structural lumber that you shouldn’t overlook.

Here are the most common lumber defects:

  • Bow is a warp on the face of a board from end to end.
  • Cup is a hollow across the face of a board.
  • Crook or crown is a warp along the edge line.
  • Knots are a part of the wood’s grain. A tight knot is usually fine. A loose or dead knot, surrounded by a dark ring, can fall out and leave a hole.
  • Twists are multiple bends or warped spots in a board.
  • Splits are cracks going all the way through the piece of wood. They’re commonly at the ends and are usually caused by mechanical processing.
  • Check is a crack along the wood’s annual growth rings. It usually doesn’t not pass through the entire thickness of the wood.
  • Shake is a crack that splits the wood along the grain. It can pass through the wood’s entire thickness. A shake differs from a split because it’s usually caused by natural growth.
  • Wane is bark or missing wood on the sides or edges of lumber. 

Choosing the lumber for your next project just got easier. Now you know which types of wood work best for which jobs. Whether you’re building a home or starting a renovation project, the right lumber makes all the difference. Find the plywood, MDF, pressure-treated lumber and all the tools and supplies you need to complete your woodworking project. Ready to get started today? Reach out to our truck rental department for pickups, vans or moving trucks to haul lumber and more.