Composite decking has become a popular choice for homeowners looking for a durable, low-maintenance alternative to traditional timber. While the material itself offers many advantages, poor installation can quickly undermine its benefits. Rushing through planning or skipping over essential details can lead to structural issues, visual inconsistencies, or expensive repairs down the line. Since 1999, we’ve seen firsthand how correct installation makes all the difference. Our composite ranges are engineered for Australia’s toughest environments, but like any premium product, they require correct subframes, spacing, and fixings to ensure optimal performance and longevity.Whether you’re a seasoned contractor or a DIY enthusiast, it’s worth understanding the most common mistakes made during installation—so you can steer clear of them. 

Choosing the Wrong Subframe Material

One of the most overlooked decisions in the decking process is the subframe material. Composite decking boards might be built to last, but if they’re laid on an inferior or mismatched frame, that durability can be compromised. Many installers opt for softwood or untreated timber to save on costs, not realising that these materials are prone to rot, warping, and structural failure over time—especially when exposed to moisture.

Supported by an industry-leading structural warranty, our Titanium, HD Pro, and Urban X decking ranges are typically installed over galvanised steel, aluminium or properly treated H3/H4 timber subframes. Using low-grade timber can compromise the structural integrity of your deck and should be avoided.

Using galvanised steel or correctly treated timber ensures your deck’s foundation is just as reliable as the boards above it. These materials offer improved strength, weather resistance, and long-term performance. When building with composite, which can last upwards of 25 years, it makes little sense to pair it with a subframe that may need replacing after only 5 to 10 years. Choosing the right base isn’t just a technicality—it’s a commitment to the lifespan of your entire structure.

Poor Spacing Between Boards

Composite boards may not behave exactly like natural wood, but they still expand and contract depending on the temperature. Failing to leave proper gaps between boards can cause them to press against one another, leading to warping, buckling, or even structural damage over time. Too little space means water and debris can get trapped, creating a breeding ground for mould and mildew.

Equally, spacing that’s too wide not only disrupts the deck’s visual appeal but can also pose safety risks, particularly for children or pets. It’s essential to follow the manufacturer’s guidelines for board spacing—this accounts for thermal expansion and environmental factors. Spacing boards properly ensures airflow, allows for drainage, and maintains the aesthetic and function of your decking.

Inconsistent spacing between composite decking boards can lead to a range of issues—from trapped moisture and mould growth to uneven expansion, visual misalignment, or safety risks. Too little space prevents drainage and airflow, while excessive gaps can compromise comfort and aesthetics.

At Brite Decking, correct board spacing is automatically maintained using our clip systems, provided free with every purchase and tailored to your chosen subframe—whether timber or steel. These systems are designed to create either a 3mm or 5mm consistent gap between boards, depending on the product range.

For projects in bushfire-prone areas, we also offer stainless steel clip systems with 3mm spacing to meet BAL compliance requirements without compromising appearance or performance.

Using the correct fixing system ensures uniform spacing, structural stability, and low-maintenance performance—preserving the look and function of your deck for years to come.

Ignoring Manufacturer Instructions

It’s easy to assume that decking boards are a one-size-fits-all solution, but each composite product comes with its own set of specifications. Ignoring the technical instructions that accompany your boards is a mistake that can unravel even the most well-planned installation. These guidelines aren’t suggestions—they’re carefully tested recommendations based on material behaviour and performance standards.

From fastening systems to joist spacing, cutting methods to board orientation, the manufacturer’s instructions are tailored to help you get the most out of your product. Skipping them can result in premature wear, voided warranties, or structural faults. Investing time upfront to read and understand these instructions is a straightforward way to avoid costly mistakes and guarantee long-term performance.

Incorrect Joist Placement

The strength of your decking boards depends heavily on what’s beneath them. Joist placement plays a critical role in ensuring stability and preventing bounce or sag. When joists are spaced too far apart, boards are left unsupported and can flex or crack under weight. On the other hand, placing them too closely can result in unnecessary material costs without any added benefit.

Most composite decking requires joist spacing of 300mm to 400mm on centre, but this varies by product. It’s also important to install joists perpendicular to board direction to provide consistent support. Taking the time to measure and align joists accurately is essential—not just for structural integrity, but for the overall feel of the deck underfoot. An unstable or uneven surface undermines both comfort and safety, especially on larger installations where misalignments can multiply across the space. Well-aligned joists are the backbone of a solid deck.

Forgetting to Allow for Expansion and Contraction

Unlike traditional timber, composite materials respond more dramatically to temperature changes. When expansion and contraction are not accounted for, issues such as board buckling, joint separation, and screw pop-ups become common. These problems not only reduce the visual appeal of your deck but can also compromise its structural soundness over time.

The solution lies in planning for thermal movement from the start. This includes leaving appropriate gaps at board ends, using expansion joints, and ensuring fasteners are compatible with composite’s movement patterns. Most manufacturers will outline the required tolerances for different climates. Planning for temperature variation is an essential, often underestimated, part of composite decking installation. Watch our quick video on expansion and contraction to see how to get it right from the start.

Overlooking Drainage and Water Run-Off

Composite boards may resist water, but the area around and beneath them must still be able to manage it effectively. Improper drainage can cause water to pool, leading to rot in timber subframes, moss growth, and slippery surfaces. Flat installations with no slope or outlets for water run-off will inevitably collect debris and moisture, especially in high rainfall areas.

Creating a slight gradient—typically around 1%—encourages water to flow away from the decking surface. Installing drainage mats or spacing boards correctly can also improve run-off. In regions prone to heavy rain, water management becomes even more crucial. Building with drainage in mind doesn’t just protect the materials—it enhances safety and reduces long-term maintenance.

While composite boards are highly water-resistant, managing moisture in and around your deck is still essential. Surface water is designed to pass through the gaps between boards – especially when the correct spacing is maintained using manufacturer-supplied clips.

However, if the joists beneath are not properly levelled, water can pool in low points over time. This not only affects timber subframes but can also encourage mould, mildew, or slippery surfaces.

To avoid these issues, it’s important to ensure the deck frame is even and free of dips or hollows that could collect water. Good airflow and correct gap spacing will help keep both the surface and the subframe dry, reducing maintenance and preserving the life of the structure.

Misusing Fasteners or Clips

Using the wrong fasteners can undermine the structural integrity of your decking and interfere with its appearance. Composite-specific fasteners are designed to accommodate movement and avoid surface damage. Yet many installations still rely on standard screws or nails, which can cause splitting, cracking, or uneven board spacing.

Hidden fastening systems are commonly recommended for a clean finish and even spacing, but they must be used exactly as intended. Over-tightening or misalignment can cause boards to sit unevenly or lift at the edges. Ensuring the clips and fasteners match both the board profile and the subframe material is essential. Taking shortcuts here might seem minor, but it will eventually result in visible flaws and functional issues.

Using the Wrong Product for the Wrong Application

Not all composite decking products are created equal—and choosing the wrong board for your environment or use case can lead to poor performance, unnecessary wear, or even non-compliance with safety regulations. For example, installing hollow or uncapped boards in coastal regions, bushfire zones, or high-traffic commercial spaces can result in faster deterioration, safety concerns, or warranty issues.

It’s essential to match your decking choice to the conditions of your project. Brite Decking offers a range of solutions tailored to specific needs—our Titanium range is BAL 29 certified and features ASA capping for extreme weather protection, while our HD PRO range provides a double-sided, UV-stable option perfect for residential decks. For budget-conscious builds, our Urban X range delivers performance without compromising durability.

Taking the time to select the right board for your environment ensures your deck not only looks great, but also performs as intended for years to come.

Rushing the Preparation Phase

It’s tempting to jump straight into laying boards, especially on a sunny weekend, but skimping on preparation almost always leads to regret. Groundworks, base levelling, and layout planning are the foundation of a successful install. If the surface is uneven or poorly compacted, your deck can settle unevenly, causing visible dips and instability.

Similarly, neglecting to plan the board layout can result in awkward cuts or unattractive joins that detract from the overall finish. Proper prep includes marking out joist locations, checking square angles, and deciding where seams or joins will be placed. A couple of extra hours spent planning and measuring can save days of fixing problems later. Laying the groundwork properly is a non-negotiable part of composite decking success. Watch our quick pre-build preparation video to make sure your composite decking project starts off on the right foot

Failing to Checking for Permits and Local Requirementsor Regulations

Every area has different rules about what you can and can’t build, particularly when it comes to raised decks or structures attached to buildings. Skipping local permit checks can lead to fines, forced removals, or complications when selling your property. It’s not just about bureaucracy—it’s about ensuring the structure meets safety standards and zoning rules.

Before you start digging or laying anything down, check with your local council or building authority. They may require drawings, site plans, or inspections depending on your location and the size of your project. While it may feel like a hassle, taking this step ensures you’re covered legally and structurally. Avoiding unauthorised builds is as much about peace of mind as it is about compliance.

While most ground-level residential decks don’t require approval, some projects – such as raised platforms, decks attached to dwellings, or builds in bushfire-prone areas – may be subject to local regulations or building codes.

It’s a good idea to check with your local council if your project involves significant height, structural attachments, or is located in a designated BAL (Bushfire Attack Level) zone. In these cases, you may need to provide site plans or select fire-compliant materials like Brite Decking’s BAL 29-rated Range.

Taking a moment to check requirements early can prevent unnecessary complications and ensure your deck meets both safety and compliance standards.

Neglecting Ongoing Maintenance Needs

Many choose composite for its low maintenance appeal—but that doesn’t mean it’s maintenance-free. Neglecting regular care can lead to surface staining, build-up of dirt, or slow drainage issues. Even though composite is highly resistant to rot and fading, it still benefits from occasional cleaning and inspection.

A simple rinse with water and a soft brush every few months can prevent debris build-up and preserve the deck’s appearance. Clearing leaves and dirt from gaps helps maintain airflow and drainage. Checking fasteners and subframes annually ensures that nothing has shifted or deteriorated. Committing to simple upkeep protects your investment and keeps your decking looking great for years to come.

One of the key advantages of composite decking is its low-maintenance appeal – but low-maintenance doesn’t mean no maintenance. Over time, dirt, leaves, and surface grime can build up, especially in shaded or high-traffic areas. While Brite Decking products are engineered to resist rot, mould, and fading, occasional cleaning helps preserve their appearance and performance.

A simple rinse with a hose and a soft-bristled brush every few months is usually all that’s required. Clearing leaves from the board gaps also supports drainage and airflow – especially important in wet or tree-heavy environments. Once a year, it’s worth checking that fasteners are secure and subframes are clear of debris or pooling water.

Thanks to features like our capped surfaces, stainless steel fixings, and hidden clip systems, Brite decks are designed for minimal upkeep. A small investment in regular care ensures your deck continues to look great and perform reliably for years to come.

Get Started the Right Way

Composite decking is a long-term investment—and when installed correctly, it delivers decades of durability, style, and performance. Avoiding these common mistakes not only saves time and cost, but ensures your deck looks great and functions as it should from day one.

At Brite Decking, we’ve supported thousands of successful installs across Australia, and we’re here to help you do the same. Whether you’re a DIYer or a professional installer, our installation guides, project videos, and friendly team can give you the clarity and confidence to build it right.

Need help getting started? Request a free sample or get in touch with our team to discuss your project today.