5/4 Decking vs 2x6: What’s the Difference? Which Is Better? (2024)

Building or resurfacing a deck provides an outdoor living area and enhances the value of a home. Selecting the best decking, 5/4 decking vs 2×6, can be a challenge. Which is better and what are the differences?

Today, 5/4 decking is more widely used than 2×6 decking. Although the same width, 2x6s are 1/2″ thicker, making them stronger and less bouncy than 5/4 decking spanning the same joist spacing. However, 2x6s cost 30% to 50% more for similar quality and appearance decking.

In this article, we’ll explain what 5/4 and 2×6 decking are, look at their key points and difference, and whether you can use 2×4 or 1×6 boards instead. Our goal is to help you identify which is better for your project, 5/4 or 2×6 decking.

What Is 5/4 Decking?

The main purpose of 5/4×6 planks is to finish the surface of a deck upon which people walk, sit, or recline, so they are typically high-quality appearance-grade lumber. They provide the surface that covers the deck framework of joists and beams to prevent slipping or falling between the joists. When selecting 5/4 deck boards there are a number of options ranging from softwoods and hardwoods – treated or untreated, composite, PVC, and even metal decking.

Softwoods such as spruce, pine, and fir are typically pressure-treated with chemicals to prevent rot and protect from insects, mold, and UV rays. Softwoods like cedar and redwoods, and hardwoods like teak, mahogany, and Ipe, have a natural resistance to rot and insects, so aren’t usually treated before installation. The type of decking material affects the budget line and aesthetics of the deck build.

A 5/4 x 6 plank is nominally 1-1/4” thick and 6-inches wide. The actual measurements though, are closer to 1” to 1-1/16” by 5-1/2”. Hard and softwood boards are planed and sanded with rounded corners or edges, and typically come in lengths of 8’, 10’, 12’, and 16’, but longer 20’ and 24’ are available at a premium. The thinner depth makes the planks lighter and more economical than thicker dimensions. They are the more common decking choice in much of North America.

The distance 5/4 deck boards can span depends on their orientation to the joists. Typically, they can span up to 16” O.C. when laid perpendicular to joists, and 12” when run diagonally to the joists. The diagonal span is reduced to 12” O.C. to minimize bounce. Greater distances in either orientation generate bounce or spring in the decking, which can lead to other issues.

2×6 Deck Boards

2×6 lumber has many purposes from floor, wall, and roof framing to furniture. They are also used as deck boards, railings, and even deck joists. Typically, when used as decking, pine, spruce, and fir planks are pressure-treated to prevent rot and protect from insects, mold, and UV rays. However, 2×6 decking may also be untreated softwoods, cedar, redwood, Ipe, teak, mahogany, PVC, composite, or extruded aluminum.

A 2×6 is nominally 2” by 6”, but after planing and sanding, its actual dimensions are closer to 1-1/2” by 5-1/2”. Deck boards are commonly available in 8’, 10’, 12’, and 16’ lengths with longer boards available as special orders.

The type of wood or material, as well as the length, affects the cost of the deck board. Softwood 2×6 decking should be high-quality appearance-grade lumber so it is more visually appealing.

The thickness of a 2×6 plank allows it to span 24” O.C. when placed perpendicular to joists, and 16” O.C. when laid diagonally. The greater thickness makes the planks more solid or less springy, and less likely to cup. The planks are thicker than most other deck boards, making them more expensive, plus they are heavier and may require a stronger substructure framing, which also increases the cost of a deck.

5/4 decking vs 2×6: Key Points

Here are a number of key points to consider when choosing between 5/4 or 2×6 decking.

What’s the Difference Between 5/4 Decking and 2×6?

Selecting the type of decking, whether it’s pressure-treated, cedar, hardwood, PVC, composite, or metal, is usually a matter of preference and budget. However, it is necessary to choose between 5/4 and 2×6 lumber for outdoor decking prior to designing and building a deck.

The thickness of the decking can affect the spacing of the joist and the elevation of the support structure. Being aware of the differences between 5/4 and 2×6 may make the decking selection easier.

Dimensions

A 2×6 is actually 1-1/2” by 5-1/2” and a 5/4 is 1” to 1-1/16” by 5-1/2”. Both types of decking are available in 8’, 10’, 12’, and 16’ lengths, and 20’ and 24’ lengths are available as special orders.

Thickness

The thickness is a key difference between 5/4 and 2×6 lumber as it affects the distance they can span, also referred to as the joist spacing, and how solid they feel. A 2×6 is 1-1/2” thick whereas a 5/4 is between 1” and 1-1/16” thick. The thicker lumber dries slower but doesn’t cup or twist as easily as the thinner planks.

Material

When referring to 2×6 or 5/4 decking, many think of pressure-treated softwoods like pine, spruce, and fir, or cedar, cypress, and redwoods. Hardwoods like mahogany, teak, Ipe, and even oak are also used for outdoor decking, as are PVC, composite, and even fiberglass and metal planks. The selection of decking greatly depends on the budget and the purpose the deck will serve.

Shape

Both 5/4 and 2×6 decking have wide, flat, 5-1/2” surfaces on the top and bottom. It is the sides or edges that may differ. Rounding the corners where the top or bottom meet the sides decreases the risk of splinters or splitting, improves water-shedding capabilities, and makes it easier to remove leaves and other debris from between the planks.

2x6s are thicker, so the sides are still square looking with rounded corners, while thinner 5/4 lumber often has a bullnose look. Harwood and manufactured 2×6 and 5/4 planks often have squared edges or corners, or smaller radial corners, giving it a smoother, more solid-looking surface.

Appearance

The appearance of the decking differs depending on the type of decking used. When looking at the profile of 2×6 and 5/4 of the same wood or material, the coloring, texture, and look are similar. However, the rounded edges do make a difference with some preferring the rounded edges and others the squared edges. The rounded edges produce more shadowing while the squared edge makes for a more solid look.

It should be noted, though, that 5/4 lumber is manufactured specifically for finishing deck surfaces. The lumber selected usually has fewer flaws so it looks better on the deck. Untreated and pressure-treated 2×6 softwood lumber is commonly used for indoor or outdoor framing and may not be as visually appealing unless it is sorted for visual appearance. High-quality appearance-grade lumber often has a greater price tag than general-purpose #1 and #2-grade lumber.

Strength

A 2×6 has a greater cross-sectional dimension and is typically a third thicker than 5/4 lumber. It is stronger and more solid, making 2x6s safer as they can support more, plus they can span further than 5/4 decking of the same material.

Weight

The weight of decking depends on the type of material used, PVC is lighter than wood, and composite is heavier than wood. Additionally, the species of wood, treatment, moisture content, and dimensions all affect the weight. 2×6 pressure-treated SPF (spruce-pine-fir) decking weighs approximately 2.36lbs per linear foot, and 5/4 lumber of the same material weighs about 1.59lbs per linear foot.

Span

The thickness of the wood affects the spacing between the joists, and vice-versa. Joists are typically spaced 12”, 16”, and 24” on-center (O.C.) apart, which not only affects the deck board choices but also the lumber size used in joists and beams, and their placement. The spacing is usually a standard measurement that factors into 48, a common construction material dimension.

Most 2×6 lumber can span up to 24” when laid perpendicular to the joists, while 5/4 usually only spans to 16”, so 2x6s require fewer joists. Greater distances result in springy or spongy feeling decking. When laid diagonally to the joists, 2x6s can span up to 16” and 5/4s are to 12” or less. Most building codes specify spacing of different dimensional lumber.

Spacing

The spacing between deck boards is important and often difficult to judge as new or wet wood will shrink as it dries. Narrow 1/8” gaps prevent debris from falling through, which can lead to dirt build-up and rot, mold, and other moisture-based damage.

Gaps that are 1/4″ allow better airflow which can reduce moisture damage but can be a hazard to fingers and toes, plus it’s easier for items and debris to fall through. Gaps between seasoned wood should be between 1/8” and 1/4″.

Cost

Decking, like all lumber, is a commodity, so the price often fluctuates from month to month, day to day, and sometimes even morning to afternoon. It also varies from location to location and the type of treatment. Availability and length of the material also affect the price. In my area, pressure-treated SPF 2x6s range from $2.31 to $2.44 per linear foot (PLF) and 5/4 range from $1.52 to $1.50 PLF.

Can I Use 2×4 for Deck Boards?

The quick answer is “YES”. However, untreated 2x4s will require yearly maintenance or they won’t last, but pressure-treated 2×4 lumber or cedar planks will. 2x4s can span joists at 24” O.C. when laid perpendicular and 16” O.C. when diagonal. They are nominally 2”x4” but actually 1-1/2” thick by 3-1/2” wide, so stronger and less bouncy than thinner lumber, and often less expensive than other options.

Can You Use 1×6 for Deck Boards?

Using 1×6 lumber for deck boards is becoming more common as they are less expensive and considered by some to be more environmentally friendly – more planks per tree. 1×6 planks are typically 12/16” or 3/4” to 13/16” thick by 5-1/2” wide. The boards aren’t normally pressure treated unless sold as fence boards, which are often thinner than 1x6s – 10/16” to 12/16” thick.

Prior to plywood and OSB, square-cut and T&G 1x6s were the common planks used for decking. They were often run diagonally across joists at 16” O.C. or 24” O.C. However, modern building codes typically limit 1×6 softwood lumber to spans of 8” on the diagonal and 12” when perpendicular to the joists, while hardwoods like mahogany can span 12” on the diagonal and 16” when perpendicular.

Airflow is important when using thinner wood, so ensure the deck is 16” or more off the ground. It is also important to read the manufacturer’s literature as some claim their products can span 16” O.C. It is also recommended that the local codes be checked before you build to be on the safe side.

2×4 or 2×6 Deck Boards?

The choice between 2×4 or 2×6 deck boards is a matter of aesthetics, budget, and time. While both 2×4 and 2×6 decking can span the same joist spacing, the width of the boards isn’t the same. A 2×4 is 3-1/2” wide and a 2×6 is 5-1/2” wide, so the 2×6 is about 40% wider. Some decks may also look better with fewer plank lines, and others with more, it’s often a matter of preference.

The real impact occurs at the budget line – a pressure-treated 2×4 ranges from $1.37 to $1.43 PLF and a similar 2×6 between $2.31 and $2.44 PLF, so the 2×4 is about 40% cheaper. The 40% cheaper, though, is offset by the 2×6 being 40% wider, which means the big difference comes down to the cost of labor and fastening hardware. Overall, 2x6s are easier on the budget line and quicker to install than 2x4s, which is why most people choose them over 2x4s.

Is It Better to Use 2×6 or 5/4 Decking?

The choice between 2×6 and 5/4 decking is one of personal preference. They are the same width, so cover the same area, require the same number of fasteners and time to install. However, 5/4 decking is lighter than 2×6, so may not require joists to be as deep as those for 2x6s. The main pull for 2x6s is strength, especially if they span joists at 16” O.C. spacing.

The cost of 5/4 decking is 30% to 50% less per linear foot than 2×6 decking of the same material and of similar quality. 5/4 decking is manufactured for decks, so the quality and appearance are often better than regular 2×6 lumber which has a multitude of uses. Since 2x6s can span joists spaced up to 24” and 5/4 (usually) only 16”, there is a cost-saving on the number of joists required with the thicker boards, but not enough to make the overall 2×6 decking cost less.

For example:

An 8’x12’ deck will require 10 joists spaced at 16” O.C. and 7 when spaced at 24” O.C. The 8-foot width will require eighteen 12-foot long 5-1/2” wide planks for decking. If 2x8x8 joists cost $16.78, that’s an extra $50.34 (3 x $16.78) for joists spaced at 16” O.C. Eighteen 12-foot 5/4 deck boards at $18.24 cost $328.32, adding the 3 joists and the total 5/4 decking cost is $378.66. By comparison, eighteen equivalent quality 12-foot 2×6, spanning joists at 24” O.C. and each costing $23.38, add up to $429.84.

The overall cost savings of 5/4 in this example would be $51.18 – not a budget-breaking decision. If spanning joists at 16” O.C. with 2x6s for a more solid and stronger deck, the overall cost would be $101.52 greater than if using 5/4 decking.

Many professional deck builders prefer to use 5/4 decking as it is lighter, less expensive, and typically of better quality and appearance than 2×6 decking. Additionally, they also prefer joists spaced at 16” O.C. for strength and durability, regardless of lumber dimensions.

Having personally spent hours going through racks of both 5/4 and 2×6 lumber for decking use, I can say it’s much easier to find quality-looking 5/4 decking than 2×6 decking, so my personal preference is 5/4 decking.