Dimensional Lumber: What You Need to Know

When it comes to building materials, there is a vast market of options to choose from. However, none can truly compare to the versatility and durability provided by dimensional lumber. Here’s what you need to know about dimensional lumber, including what it is, what it’s used for, and how it’s graded.

What Is Dimensional Lumber?

Dimensional lumber is a type of wood that is milled and cut to a specific thickness and width based on predefined, standardized sizes. For ease of use, length is not factored into the sizing. You can, for example, order a 2x4 board that is twelve feet long, which can you then cut as needed. When shopping for building materials at a lumberyard or home center, any lumber you purchase would be considered dimensional lumber.

Often made from softwood trees like Southern yellow pine, spruce-pine fir, Douglas fir, and hem fir, dimensional lumber is most often used in wood-frame and platform-frame construction. By developing standard sizes and grades for dimensional lumber, the building materials industry can control costs and minimize waste for more efficient lumber sales and construction.

What Is The Actual Size of Dimensional Lumber?

Dimensional lumber sizing can be somewhat confusing, as there is a difference between the nominal and actual dimensions of the lumber. The nominal dimensions exist in name only. The actual size of dimensional lumber is determined by using a tape measure or straight edge to measure the dimensions of the wood. A 2x4, for example, is an example of a nominal size. You can think of it as a nickname used to categorize lumber. The actual size of a 2x4 is 1 ½ inches by 3 ½ inches.

How To Determine the Actual Dimensions of Dimensional Lumber?

While measuring dimensional lumber or using a reference table is the best way to determine the actual dimensions of your lumber, there is a simple rule you can use to figure it out for yourself.

• For lumber with a nominal size smaller than 1”: Subtract ¼”

• For lumber with a nominal size larger than 2” but smaller than 8”: Subtract ½”

• For lumber with a nominal size of 8” or larger: Subtract ¾”

What Dimensional Lumber Grades are Available?

• Select Structural Lumber: Highest dimensional lumber grade available

• No. 1 & BTR Lumber: Similar to select structural lumber.

• No 2. Lumber: Most common grade for framing

• Construction Grade Lumber: Used for light framing

• No.3 Lumber: Allows more defects and knots

• Stud Grade Lumber: High strength and stiffness values

• Utility Grade Lumber: Lowest grade of dimensional lumber

What Are the Uses of Dimensional Lumber?

Dimensional lumber can be used for a wide range of construction, manufacturing, and industrial applications. While it is most often used for wood frame construction, including for walls, floors, and roofs, it can also be used in decking, fencing, crating and packaging, trusses, and concrete forms.

Where To Buy Dimensional Lumber?

It depends on the size of the project. If you’re an individual working on a DIY home renovation or woodworking project or a contractor looking for larger quantities of lumber for a big project, you can likely find dimensional lumber at Home Depot, Lowe’s, or a local lumberyard near you. If you’re a lumber supplier, managing a large scale construction project, or a manufacturer who needs a larger shipment of lumber, you can work with a wholesale lumber supplier like AIFP who can leverage their relationship with mills across the country to get you better prices and facilitate the delivery of the lumber.