How Thick Is Composite Decking? A Complete Homeowner’s Guide to Deck Board Sizes

Every strong deck begins with a single detail most homeowners overlook—its thickness. Understanding how thick composite decking should be is the foundation of choosing the right materials, achieving long-lasting strength, and creating an outdoor space designed to withstand the test of time. At Northwest Decks, we believe that great decks are not just built—they’re engineered with precision, purpose, and the right knowledge.

In this guide, we’ll break down composite board thicknesses, board profiles, solid boards, and how leading brands like Trex and TimberTech influence decking thickness. Whether you’re planning a brand-new deck or upgrading your outdoor living space, this complete breakdown will help you make confident, informed decisions.

Understanding the Basics: How Thick Is Composite Decking?

One of the first questions homeowners ask is: how thick is composite decking, really?
Most composite decking boards fall within a standard thickness of 1 inch to 1.25 inches. Some premium or commercial-grade boards stretch slightly beyond this range, especially if a thicker board is needed for unique structural demand.

Brands like Trex, TimberTech, and similar manufacturers typically offer composite boards within this common range, but variations exist depending on the board profile, design, and board size.

At Northwest Decks we help homeowners evaluate which deck board thickness makes the most sense for their joist spacing, deck design, and long-term durability goals.

What Determines Composite Decking Thicknesses?

Composite decking thicknesses are not random—they’re engineered for strength, flexibility, and proper support. Several factors play into board thickness:

• Board profile (solid, scalloped, or grooved)
• Deck board application (ground-level, raised deck, rooftop deck)
• Joist spacing requirements
• Material composition, such as composite, PVC, or hybrid blends 

A thicker composite board often provides enhanced rigidity, particularly useful when joists are spaced at wider intervals. Northwest Decks often recommends reviewing joist spacing first before choosing your deck boards to avoid sagging or structural issues later.

Role of Board Profile in Decking Thickness

The board profile you choose heavily influences decking thickness. There are three common profiles:

Solid Boards

These boards look and feel most like natural timber and typically feature the thickest structure. They offer enhanced strength, ideal for raised decks or high-traffic areas. Many homeowners prefer solid boards for longevity, and Northwest Decks frequently installs solid deck boards for customers seeking maximum durability.

Scalloped Boards

These boards have a lighter interior, reducing material cost without sacrificing performance. Scalloped boards are often slightly thinner due to the curved underside.

Grooved Boards

These are designed for hidden fastener systems and do not necessarily affect overall board thickness, but they do impact installation methods.

Regardless of profile, each board type has a recommended deck board thickness range to ensure safe, long-lasting results.

Standard Composite Decking Thickness vs. Thicker Options

Homeowners often ask whether they should choose a standard board or a thicker board. Standard composite decking is usually around 1 inch thick, which is ideal for most homes. But thicker options offer additional support and resistance.

A thicker composite deck board benefits projects that include:

• Larger joist spacing
• Heavy outdoor furniture
• High foot traffic
• Multi-level decks

At Northwest Decks, we help customers compare board thicknesses to ensure their choice aligns with performance expectations and the structure beneath the deck.

How Leading Brands Like Trex & TimberTech Influence Decking Thickness

Brand matters when determining decking thickness. Composite manufacturers such as Trex, Timbertech, and premium PVC brands create boards with varying sizes, densities, and profiles.

Trex

Trex composite boards generally offer consistent thickness across product lines, typically around 1 inch. Their scalloped options may be slightly lighter but maintain structural reliability.

TimberTech

TimberTech provides both composite and PVC boards, with PVC often featuring a slightly different board thickness due to material structure.

At Northwest Decks, we regularly work with both brands and can help homeowners compare deck board thickness to choose the ideal fit.

Board Size and Decking Thickness: Why It Matters

Board size and decking thickness will affect:

• Overall deck stability
• Joist spacing requirements
• Resistance to flexing and sagging
• How long does your deck last under stress 

For example, a standard thickness board might require joists spaced at 16 inches, while a thicker board could support wider spacing. Proper spacing reduces the risk of bending, especially on larger decks where dead weight (like furniture, grills, or pergolas) adds up.

Northwest Decks always evaluates both board size and thickness during project planning to deliver a safe, durable, and structurally sound deck.

Deck Board Thickness and Joist Spacing: The Relationship You Can’t Ignore

Many homeowners don’t realize the connection between deck board thickness and joist spacing. If joists are too far apart for the thickness of the deck board, the boards may flex or fail over time.

General guidelines:

• Standard composite boards: 16-inch spacing
• Thicker composite boards: up to 24-inch spacing
• PVC boards: typically require closer spacing 

At Northwest Decks, we follow all manufacturer specifications to ensure your deck boards sit securely with zero flexing, warping, or premature damage. The right spacing not only protects your investment but also enhances the overall user experience when walking on your deck.

Composite Boards vs. PVC: Does Material Affect Thickness?

.Composite boards often fall into a predictable thickness range, while PVC boards may vary because PVC is lighter and more flexible. PVC may require either extra support or specific thickness options to match composite performance.

The team at Northwest Decks helps customers compare composite and PVC materials to determine the board thickness that provides optimal strength while achieving the desired look.

Why Choosing the Right Deck Board Thickness Protects Your Investment

The right decking thickness can literally extend the lifespan of your deck by years. A thicker board or a well-engineered standard thickness board can:

• Reduce flexing and movement
• Protect the structural frame
• Provide long-term stability
• Enhance safety
• Support heavy outdoor activities 

With Northwest Decks, you’re not just choosing deck boards—you’re choosing proper engineering, expert guidance, and a team dedicated to creating decks that last for decades.

Final Takeaway: Choosing the Ideal Thickness for Your Composite Deck

So—how thick is composite decking? While typical boards fall between 1 and 1.25 inches, the right thickness depends on your deck’s size, design, joist spacing, and long-term usage.

Whether you’re planning a ground-level deck, a wraparound outdoor living area, or a multi-level structure, Northwest Decks provides expert guidance to ensure you choose the perfect decking thickness, board profile, and material for unmatched performance and peace of mind.

Contact Us

Build your deck with confidence—and the experts who know decking thickness better than anyone. If you want a reliable, long-lasting, and beautifully crafted outdoor space, connect with Northwest Decks today. Let’s create a deck that stands strong, looks stunning, and elevates every moment you spend outdoors.