The Role of Deck Breaker Boards

When designing and building your deck, it’s all about understanding how each element contributes to the overall look and functionality. A small but impactful feature that I feel deserves more attention is the breaker board. With decades of deck experience under my toolbelt, I can attest that a well-placed breaker board can make a big difference in both design and durability.

So, what exactly is a breaker board? Depending on the deck layout, it runs perpendicular or diagonally to the other decking boards. As the name suggests, the board breaks the surface into sections. Breaker boards can be a design choice, but they also offer practical benefits. In this post, I’ll take you through the ins and outs of breaker boards and explain why they may be a smart addition to your deck project.

Read on to understand breaker boards, how they work, and how to install them to boost your deck’s longevity and visual appeal.

What Are Deck Breaker Boards?

Deck breaker boards are boards installed either perpendicular or at an angle to the field decking boards, serving two primary purposes:

They create a visual break in the decking pattern, defining a separation between deck sections and adding a design element.
Breaker boards provide a practical solution for larger decks to complete long spans of decking while delivering greater stability.

How Breaker Boards Work

Regardless of your reason for using breaker boards—whether for design reasons or to manage the layout of a large deck—they will help manage the natural movement of your decking.

By interrupting long runs of boards, a breaker board provides a strategic break that allows each section to expand and contract independently. This minimizes stress on your decking, preventing pressure buildup that can lead to warping, cupping, or splitting.

Butt Joint Alternative

Debating whether to use a breaker board or traditional butt joints? Here’s why I choose breaker boards for my deck projects:

Increased Durability: Breaker boards help reduce the risk of buckling, warping, or splitting. End-to-end, butt-joined boards are particularly prone to these issues because they lack expansion gaps at their ends.
Easier Installation: Breaker boards make aligning and securing long runs of boards on larger decks simpler. They are particularly useful in areas where precision alignment of traditional butt joints may be difficult.
Cleaner Look: Breaker boards provide a more professional appearance than butt joints, which are prone to unevenness.

Benefits of Deck Breaker Boards

Design Versatility

Breaker boards act as natural transition points, which I find opens up creative possibilities. They make it easy to shift the orientation of your field decking, whether you’re going from a parallel layout to an angled design or even creating a herringbone pattern. Breaker boards support unique patterns without complicating the installation.

I also use breaker boards to separate different areas on the deck, like a lounging and dining areas, or to divide a large deck into smaller zones.

I’ve been asked about using a different material for the breaker board than the rest of the deck. While it’s possible, I recommend the same decking material for uniform expansion and contraction. Using a different colour can create contrast, and pairing it with a matching picture frame edge always looks sharp.

Deck Stability

Breaker boards contribute to the overall stability of your deck by providing a break in the decking to evenly distribute any stress caused by the expansion and contraction of the boards. This is particularly important in Australia’s wet and humid climate. By reducing the pressure on individual boards, breaker boards help prevent issues like cupping or splitting.

Easy Installation

Some homeowners worry that breaker boards would complicate installation, but they actually simplify it in most cases. By breaking up long runs of decking, you can use shorter, more manageable board lengths. This can reduce waste and make the installation process more efficient. Breaker boards are also a practical solution for decks with irregular shapes or obstructions.

Guide to Installing Your Deck Breaker Board

When it comes to breaker board installation, you might wonder whether to install it before or after the field decking. To streamline the process, I recommend installing the breaker board after your deck boards are in place. This allows you to cut the main field boards all at once with your circular saw for easy alignment and a professional finish. Here’s that method:

Step 1: Install Blocking Joists

Decide on the placement of the breaker board. Install blocking joists—short pieces of lumber attached perpendicularly between the joists—beneath the breaker board location for support to prevent sagging or twisting.

Step 2: Cut the First Field Boards

Determine the spacing between the breaker board and your decking boards, ensuring consistent gaps matching your other boards for a uniform look and proper drainage. Add the gaps on either side to the width of the breaker board.

Using that combined width, cut the first field deck boards (those furthest from the house), centred over your blocking joists, to accommodate the breaker board. Trim the boards against the house; your circular saw won’t be able to get close enough to the house to complete the cut later.

Step 3: Install the Field Deck Boards

Install the field decking boards. For boards not cut in Step 2, let them slightly overhang the edge of the blocking joists where the breaker board will be installed. Leave these boards long for now.

Step 4: Trim Field Boards

Snap chalk lines between the ends of the cut boards (Step 2). With your circular saw, follow your line, carefully trimming the overhanging boards to make space for the breaker board.

Step 5: Position and Secure the Breaker Board

Cut the breaker board to length, then position it between the cut ends of your decking boards. Secure it with colour-matched deck screws or a plug system. Predrill holes and install fasteners 25 mm from the board’s edge, spaced about 400 mm apart.

Pro Tip: Be sure that the blocking joists under the breaker board are not shared with the field decking boards. The decking ends should have their own blocking joist for support.

Breaker boards are more than just a design feature—they’re a practical solution that can extend the life of your deck while giving it a polished appearance. Consider integrating breaker boards into your design as you plan your decking project. They’re a simple, smart addition that delivers big in both form and function.

Dave Kile

Dave Kile is the owner of IBP, LLC, the company behind some of the decking industry’s most successful innovations, including Trex® RainEscape®, Trex® Protect™ and Trex® Seal. Over the past three decades, he has achieved incremental success by immersing himself in the industry, listening to customers and bringing new products to market that improve efficiency and effectiveness.