Understanding Basic Types of Lumber

Bundles of lumber.

You have many varieties of lumber to choose from, and some are more appropriate than others depending on the project at hand. When you're at the home improvement center or lumberyard, know what you're looking for and why.

Western Lumber

Known for its ease of workmanship and nailing as well as strength and dimensional stability, Western lumber includes more than 15 commercially important Western softwood species. The most common species are Douglas fir and Hem-fir. This can be classified as High-Quality Appearance, General Purpose Board or Radius-Edged Patio Decking Grade.

The Western Wood Products Association (WWPA) has a rigorous inspection and quality control process. Lumber with the WWPA logo indicates the lumber has passed that quality control process. Lumber with only the “WWPA Rules” stamp indicates the lumber has been graded according to the WWPA rules, but not been inspected by WWPA. Use this lumber for basic building projects and framing.


Most redwood sold is heartwood and sapwood grade. Each type comes in several grades, from a fine finish appearance to a rougher, less attractive finish. Heartwood contains natural barriers to termites and decay and is suited for applications that come into contact with the ground. Sapwood contains cream-colored streaks. It should not be used in contact with the ground. Architectural redwood is the strongest redwood. It is normally kiln-dried and used for structural and finish applications. Garden redwood comprises lower grades that are not kiln-dried and are commonly used for decks, fences, and other outdoor garden uses.

Southern Pine

Southern pine has high strength, resistance to wear, and holds fasteners well. It is often used in homes and other structures. The characteristics of this type of wood range from one through four.

No. 1 has the highest quality and best appearance

No. 2 is characterized by tight knots and is generally free of holes

No. 3 is good, serviceable sheathing, usable for many applications without waste

No. 4 contains usable portions at least 24 inches long

Treated Lumber

Treated lumber undergoes a process to resist weather, termites, and fungus. The treatment involves chemical preservatives forced deep into the cells in the wood under pressure. The wood is used for decks and for various other outdoor consumer use is generally treated with an inorganic chemical. In 2004, the EPA outlawed the use of arsenic as a method of treating wood. ACQ and copper azole are the current popular chemicals used.

Treated wood still absorbs water, and the treatment is not considered waterproof, but rather decay-proof. Wood species typically used include Ponderosa pine, Lodgepole pine, Douglas fir, and Southern yellow pine. You must wear respiratory protection when cutting treated lumber.

Pine Shelving

This lumber is 1-inch thick and of varying widths and lengths. Most consumer inventories range from 1 x 1-inch to 1 x 12-inch, up to 12' long. From 1 x 1 to 1 x 6, increments increase by one inch. Then, lengths increase in 2" increments from 1 x 8 to 1 x 10 and 1 x 12. Most consumer sales will be in 4 and 6-foot lengths. No. 4-grade pine is commonly called “garage shelving.” Many people use it for basements and garages where looks are not important.

This guide to understanding the basics types of lumber will help you with your next project. Now, you'll be able to walk into the hardware store with confidence.