What is 5/4 Lumber? (Wood Thickness + More) [2024] (2024)

Are you embarking on a woodworking project with a hint of uncertainty about lumber dimensions? Many craftsmen have encountered the frustration of commencing a project without a clear grasp of lumber terminology, only to discover their creation marred by unevenness or inadequacy, necessitating a fresh start.

Fear not, let me unravel the enigma of 5/4 lumber, and tackling the intricacies of lumber dimensions, paving the way for smoother, more successful woodworking endeavors.

Forcalculating lumber, nominal measurements are sold rather than actual measurements. Furthermore, the standards for hardwoods and softwoods are different.

As a common pre-cut of lumber, the actual nominal size of 5/4 is 1 ¼ inch. This is the rough size or actual thickness, and 1 ⅛ inch is the exact size when surfaced on 1 side. When surfaced on 2 sides, the actual size is 1 1/16 inches.

For instance,4/4 or four-quarters lumberis 1 inch thick in the rough. 5/4 is 1 1/4 inches thick, whereas 12/4 would be 3 inches thick.

Most of the time, you will lose about ¼ inch of material when you smooth out rough lumber. So, as a general rule, 4/4 stock surfaces down to 3/4-inch-thick wood and 5/4 surfaces down to 1-inch-thick wood.

The length of the boards is usually precisely what you want to order, though there are generally only stock pieces of even lengths available.

The most common sizes are 8′, 10′, 12′, 14′, and 16′. Longer lengths up to 24 feet are available in larger timbers, such as 2x8s, 2x10s, and 2x12s.

A 5/4lumber’s actual dimensionis 1” x 5.5”. Thus, you only get two-thirds of a 2×6 board if you use a 5/4 decking.

Decking is one of the most popular projects for 5/4 boards because it is generally a cost-effective and environmentally friendly option.

For example, if building two similar-sized decks, one with 5/4 boards and one with 2×6 boards, the 5/4 board deck will require fewer trees to be cut down to get the same amount of wood as the 2×6 board deck.

Read Next:Actual Size of 2×6 Lumber

When you embark on your next lumber-buying journey, keep in mind that the designation “5/4” pertains to the thickness of the wood.While it may appear to be a straightforward fraction denoting thickness, it’s important to note that 5/4 isn’t an absolute measurement.

It’s more of a rough approximation, serving as a starting point. If precision is your aim, achieving a precise 1 ¼-inch depth may require selecting lumber that’s slightly thicker than the nominal 5/4 designation. This subtle nuance in measurement can make a significant difference in your woodworking projects, ensuring a polished and professional finish.