Key Takeaways -

• Choosing the right deck board thickness ensures durability, safety, and aesthetic appeal for your decking project.
• Thicker boards are ideal for heavy loads, high-traffic areas, and wider joist spacing.
• Material choice, such as wood or composite, impacts thickness requirements and long-term performance.
• Consistency in board thickness prevents uneven surfaces and enhances deck safety and functionality.

Choosing the right decking thickness is essential for creating a safe, durable, and attractive outdoor space. The actual thickness of decking boards affects how strong and long-lasting your deck will be, as well as its overall look and feel.

This article will cover the key factors to consider when selecting the right thickness for your decking, including the differences between wood and composite materials. We’ll also explain how the right thickness can improve safety and enhance the appearance of your deck.

Keep reading to learn how to choose the perfect decking thickness for your needs. Whether it’s for your home or a commercial project, understanding these basics will help you build a deck that looks great and stands the test of time.

Why Deck Board Thickness Matters

Material Strength

The strength of your decking material impacts its required thickness. Softer woods like cedar and pine need thicker boards to maintain structural integrity, as they are less dense and more prone to sagging. Hardwoods like Ipe, being naturally stronger, can use thinner profiles without compromising durability.

Composite materials, on the other hand, offer superior strength and resistance to rot, mould, and weathering, making them a reliable choice with consistent performance across different thicknesses.

Deck Joist Spacing

Joist spacing is crucial in determining the appropriate deck board width. For residential decks with standard 16-inch spacing, 1-inch (5/4) boards are generally sufficient. Commercial decks, often designed for heavier loads and 24-inch spacing, require thicker boards (1.5 inches) to prevent sagging.

In the UK, wider joist spacing combined with thicker boards can also reduce material and labour costs by requiring fewer joists.

Application Type

Residential and commercial decks have different requirements. Residential decks used for light entertainment can typically use the standard deck board size. In contrast, commercial decks that handle high foot traffic or heavy furniture require thicker boards to ensure long-term stability and safety.

Examples include high-traffic areas like public boardwalks versus low-traffic private patios.

Deck Surface Elevation

Consistency in board thickness is essential to maintaining a smooth, safe deck surface. When replacing or upgrading sections, matching the existing thickness prevents uneven surfaces that can create trip hazards.

Phased upgrades, such as transitioning from wood to composite materials, should consider thickness compatibility to avoid height mismatches while ensuring a seamless appearance.

Standard vs. Thicker Decking Boards

Standard Decking Boards

Standard decking boards are typically 1 inch thick, often referred to as 5/4 boards. They are ideal for residential decks designed for light use, such as small patios or private gardens. These boards are best suited for projects with standard joist spacing (16 inches) and lighter loads.

Their thinner profile makes them cost-effective for low-traffic areas, offering a balanced combination of durability and affordability.

Thicker Decking Boards

Thicker decking boards, usually 1.5 inches thick (2x6 boards), provide a sturdier feel underfoot and are designed for heavier loads. They can span wider joist spacing, making them ideal for commercial builds, docks, or high-traffic areas like boardwalks.

Thicker boards are more durable, offering better resistance to warping and sagging, especially in areas exposed to extreme weather or heavy use. These boards ensure long-term reliability for demanding applications (1).

Decking Thickness and Material Choice

Traditional Wood Decking

The type of wood you choose affects the required thickness of your decking boards. Softer woods like cedar or pine often need thicker boards to ensure structural integrity and minimise the risk of warping under pressure.

Hardwoods like Ipe are naturally stronger, allowing thinner profiles without sacrificing durability. Wood decking offers a natural look, but the longevity and resistance to warping vary based on the material's density and quality, making the right choice essential for long-term performance.

Composite Decking

Composite decking offers superior durability and flexibility in thickness options. Many brands, like TimberTech or Oakio, provide boards in both standard and thicker profiles to suit various applications.

These boards are resistant to weather damage, mould, and rot, ensuring a longer lifespan with minimal maintenance. Composite materials also maintain their appearance over time, making them a practical and attractive choice.

Benefits of Non-Wood Materials

Non-wood materials, such as composite or PVC, provide excellent resistance to moisture, insects, and rot, making them ideal for outdoor spaces. They are also eco-friendly, often made from recycled materials, contributing to sustainability.

With options for various thicknesses, non-wood materials can be tailored to match both residential and commercial decking needs, offering reliability and long-term value.

Factors to Consider When Choosing Thickness

Intended Load and Usage

The purpose of your deck plays a major role in selecting the right thickness. If you plan to host large gatherings or use heavy furniture, thicker boards are essential for distributing weight evenly and preventing sagging.

High-traffic areas or commercial decks require 1.5-inch boards to ensure longevity and durability under constant use. For lighter residential applications, standard 1-inch boards are usually sufficient.

Aesthetic Preferences

Thicker boards create a bold, substantial look, adding a premium feel to your deck. For a unique design, consider mixing different board widths and thicknesses to achieve a custom pattern or texture. These choices not only enhance the visual appeal but also help create a deck that reflects your personal style.

Budget Considerations

Although thicker boards may have a higher upfront cost, they can reduce material and labour expenses by allowing for wider joist spacing and fewer joists overall.

Balancing cost with performance is crucial for UK-specific projects, where both durability and affordability are priorities in creating a long-lasting deck.

Frequently Asked Questions

Can I Use Plywood for the Deck Floor?

Plywood is not typically recommended for outdoor deck floors as it is not designed to withstand prolonged exposure to moisture, weather, or heavy loads. While marine-grade plywood can resist water to some extent, it is better suited for temporary or interior applications.

For a durable and long-lasting deck, use wood or composite decking boards specifically designed for outdoor use.

How Do I Know If I Have the Right Deck Board Size?

The right deck board size depends on factors like joist spacing, the deck’s intended use, and material type. Boards that are too thin for wide joist spacing or heavy loads may sag or warp over time.

Always check your local building codes and manufacturer recommendations to ensure the chosen board size is safe and appropriate for your project.

Can Thinner Decking Boards Be Used with Closer Joist Spacing?

Yes, thinner decking boards can be used if the joist spacing is reduced, typically to 12 inches or less. Closer spacing provides additional support and prevents sagging or flexing underfoot.

This can be a cost-effective solution for certain applications, but ensure the substructure is designed to accommodate this adjustment.

Conclusion

Choosing the right deck board thickness is crucial for the success of your decking project. The thickness impacts the safety, durability, and overall appearance of your deck, whether it’s for residential or commercial use.

By considering factors such as material strength, joist spacing, and intended usage, you can make an informed decision that ensures long-lasting results. With the right approach, your decking will not only look great but also stand the test of time.

Sources -

1. https://www.edecks.co.uk/blog/decking-accessories/what-thickness-of-decking-is-best/