The 2×4 refers to the rough-cut green wood: it shrinks during drying, then the dried wood is planed smooth, so the finished lumber is supposed to end up at 1.5″x3. 5″. While it doesn’t really shrink that much, the mills get more usable finished 2×4’s from a given tree if they cut them slightly smaller to begin with.

Why is a 2×4 actually smaller?

The simple reason why 2×4 is not 2 inches by 4 inches is that lumber mills trim off rough or warped surfaces of a 2×4 to give it a more polished and finished look. By planning the lumber on all four sides, the original 2×4 is now reduced to 1 ½ inches by 3 1/2 inches.

When did 2×4 change size?





This pressured further compromise because thinner 2x4s were a way to compete in price with wood alternatives. Size standards, maximum moisture content, and nomenclature were agreed upon only as recently as 1964. The nominal 2×4 thus became the actual 1½ x 3½, imperceptibly, a fraction of an inch at a time.

Why are wood measurements off?

The “nominal” cross-section dimensions of a piece of lumber, such as 2 X 4 or 1 X 6, are always somewhat larger than the actual, or dressed, dimensions. The reason is that dressed lumber has been surfaced or planed smooth on four sides (called S4S). The nominal measurement is made before the lumber is surfaced.

Why isn’t a 2×4 actually 2×4?

Now, most timber is milled and planed to give it a little more of a finished look, and a little more of a consistent size and profile. Because of this extra milling, a 2×4 no longer measures a full 2 inches by four inches. Instead, a 2×4 is really only 1 1/2″ by 3 1/2″.

When did lumber dimensions change from actual to nominal?

Early concepts called for rough lumber to be of full nominal size, often in the dry condition. After World War I, the increasing demand for construction lumber led to the first national size standard in 1924. This was revised in 1926, 1928, 1939, and 1953, while still another revision is proposed for adoption in 1964.

Why did lumber get smaller?





Through the drying process, the boards naturally shrink, as moisture leaves the beams. The real shrinkage, however, comes when the “rough-sawn material” is sent to a planer, which rubs the surface of the wood down into the smooth shapes you can purchase at a hardware store.

Why is a 4×4 actually 3.5×3 5?

no, it is just a bit over 3.5″x3. 5″ for clearance. 2×4 and 4×4 boards are no longer the actual number, but as you state–they are 1/2″ LESS. the base fits nicely to a standard 4×4.

When did they stop using dimensional lumber?

The answer to your question varies from location to location. In general, homes built before World War II were likely to be built with rough-sawn full-dimension 2x4s. During the late 1940s or early 1950s, builders in many areas of North America switched to planed 2x4s that measure 1.5″ x 3.5″.

What does it mean when someone calls you 2 by 4?

2. That measures two inches by four inches, two feet by four feet, etc.

Why do two by fours have rounded edges?



2×4 have rounded edges as it’s very beneficial to the wood itself and those working with it. They reduce the number of injuries like unwanted splinters during the handling and manufacturing process and also ensure that the lumber stays looking its best all throughout until the customer sees it.

What is the difference between framing lumber and dimensional lumber?

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.

What type of 2×4 is used for framing?

For framing, choosing grade 2 or better is recommended. Moisture content – dry wood provides the best lumber for framing and the best way to ensure dryness is to look for wood labelled KD-HT, which means kiln dried and heat treated (to eliminate any possible pests).

What wood is 2×4?



One of the most commonly used two-by-fours for framing is made from softwood known as Douglas fir, with hemlock a close competitor. The two species share similar qualities of strength, appearance and durability and are often marketed together and sold as Hem-fir.

Which wood is most commonly used for house construction?

Standard SPF (spruce-pine-fir) lumber – Softwood wood choices: Light structural lumber is mainly used in the residential construction of single family homes. This timber is milled from softwood trees (spruce, fir and pine) that are sawn and machine-planed to standard dimensions (2×4″, 2×6″, 2×8″, etc.).

What is the best grade of 2×4?

2 Lumber. No. 2 lumber is the most common grade for framing. Lumber of this grade contains few defects, but knots are allowed of any quality as long as they are well spaced and do not exceed the size regulations.

What wood do builders use?

Hardwoods include ash, elm, maple, and oak. Softwood trees include cedar, fir, and pine. Hardwood construction is often used for walls, ceilings, and floors. Softwood woodworking is commonly used to make doors, furniture, and window frames projects.

What type of wood is best for framing a house?



The most popular softwoods are cedar, fir, pine and spruce. Softwood trees grow faster, and their wood has straighter grain, making it ideal for framing, construction and outdoor projects.

What is cheaper to buy typically hardwood or softwood?

Hardwood is typically more expensive than softwood. Softwood is typically less expensive compared to hardwood. Hardwood has a slower growth rate. Softwood has a faster rate of growth.

What is the difference between #1 and #2 grade lumber?

Typically wood that is two or more inches thick is graded only for strength, denoted by #1, #2 and so on. And because stronger lumber has fewer and smaller knots, it’s typically more attractive. So the general rule of thumb for lumber grades is this: the lower the number, the more strength and better appearance.