Nominal vs. Actual Sizing: Decoding Lumber Dimensions at Niagara Sawmill

Understanding the difference between nominal and actual sizing is crucial when working with lumber for any project. At Niagara Sawmill, we often get questions about lumber dimensions, and we’re here to break it down for you. By understanding how the milling process affects the final size of your lumber, you can plan your project with confidence and precision.

The Milling Process

When logs arrive at a sawmill, they are cut into full-dimension pieces. For example, a 4″ x 8″ timber is initially milled to measure exactly 4 inches thick and 8 inches wide. However, when these timbers reach our mill, they undergo further processing to ensure quality and a smoother finish.

To enhance the lumber’s appearance and remove surface imperfections or discoloration, each side of the timber passes through our bandsaw. This process removes approximately 1/8″ from each side. After milling, the original 4″ x 8″ timber becomes 3-3/4″ x 7-3/4″, which is its actual size.

What Are Nominal and Actual Sizes?

When you visit a lumber yard or supply store, you’ll notice that lumber is sold based on its nominal size, such as 2″ x 4″. However, the actual size of these boards is smaller due to additional processing steps.

Example: Standard Construction Lumber

A nominal 2″ x 4″ board is kiln-dried and surfaced on four sides (S4S), which removes material and rounds the edges (known as “eased edge” or EE). After this process, the actual size of a 2″ x 4″ is 1-1/2″ x 3-1/2″ S4SEE.

At Niagara Sawmill, we also use nominal sizes when quoting projects but always note the actual finished size. For instance, if you order 2″ x 4″ Yellow Cedar decking, you’ll receive kiln-dried, S4SEE boards with an actual size of 1-1/2″ x 3-1/2″.

Bandsawn and Green Lumber

Things can get more complex when working with green (wet) or bandsawn lumber. For example, a nominal 2″ x 4″ board that is bandsawn will finish at 1-3/4″ x 3-3/4″, as our bandsaw process removes less material compared to S4SEE lumber.

Why Does This Matter for Your Project?

The difference between nominal and actual sizing impacts how you plan and build. Whether you’re framing a structure, building a deck, or crafting furniture, precise measurements ensure the success of your project. Here’s how we can help:

• Clear Communication: When you provide details about your project, we’ll guide you in selecting the best lumber size and type for your needs.

• Transparency in Sizing: We’ll always clarify the actual dimensions of the lumber you’ll receive, helping you avoid surprises.

• Custom Milling: Need specific dimensions? Let us know! We can tailor your order to suit your exact requirements.

• 
  

Plan with Confidence

Understanding the nuances of lumber sizing allows you to plan and execute projects more effectively. At Niagara Sawmill, we’re committed to helping you navigate these details and providing high-quality lumber tailored to your needs.

Have questions or need advice on your next project? Reach out to us today! Our team is always ready to assist.

Stay tuned for more tips and insights from Plank Perspective, Niagara Sawmill’s blog!