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Learn how to install composite decking with this comprehensive guide. Discover the benefits, necessary tools, site preparation, and what to put under composite decking.


At ALU Installations, we pride ourselves on transforming outdoor spaces with high-quality composite decking. Known for its durability, low maintenance, and aesthetic appeal, composite decking is an excellent choice for enhancing your garden or patio. This guide walks you through our meticulous process of installing composite decking, ensuring a beautiful and lasting result.

Benefits of Composite Decking

Composite decking offers numerous advantages over traditional wood decking. It resists warping, splintering, and rotting, ensuring longevity and minimal upkeep. Made from a blend of wood fibres and plastic, composite decking is also eco-friendly and available in various colours and finishes, allowing for a customised look that complements your home.

Planning Your Composite Decking Project

The first step in any decking project is thorough planning. We begin by discussing your vision and requirements, considering deck size, shape, and location factors. Our team assesses the site to ensure it’s suitable for decking and helps you choose the right materials and design to match your needs.

Tools and Materials Needed

To achieve a professional finish, we use high-quality tools and materials. Our essential tools include tape measures, levels, circular saws, drills, and decking screws. We also recommend using high-grade composite decking boards, joists, and appropriate fasteners to ensure durability and stability.

Preparing the Site

Site preparation is crucial for a successful decking installation. We start by clearing the designated area of any grass, rocks, or debris. The ground must be levelled to create a stable foundation. This might involve adding or removing soil and compacting the ground to provide a firm base for the decking structure.

What Do You Put Under Composite Decking?

A solid foundation is vital for the longevity of your deck. We emphasise the importance of a well-prepared substructure, which typically involves pressure-treated wood or metal frames. We often lay a moisture barrier, such as landscaping fabric or gravel, under the decking to prevent moisture damage. This helps in water drainage and reduces the risk of mould and mildew.

Laying the Foundation

The next step is building a robust frame. We construct the frame using joists and ledger boards, ensuring it’s square and level. Joists are installed at regular intervals, usually 16 inches apart, to support the decking boards strongly. This meticulous framing ensures that the deck remains stable and secure over time.

Installing the Composite Decking Boards

Once the frame is complete, we install the composite decking boards. Each board is measured and cut to fit perfectly. We use precise cutting tools to ensure clean edges. Fastening techniques are crucial; we prefer hidden fasteners for a seamless look, although traditional screws are also used for added security. Proper spacing between boards allows for expansion and contraction, vital for maintaining the deck’s integrity.

Finishing Touches

The final steps involve adding finishing touches that enhance the deck’s functionality and appearance. We trim any excess material and add edging for a polished finish. Installing railings and steps is also essential for safety and accessibility. These elements are carefully chosen to complement the overall design of your composite decking.

Maintenance and Care Tips

Composite decking requires minimal maintenance, but regular cleaning is necessary to keep it looking its best. We recommend using a mild detergent and water to remove dirt and debris. To prevent scratches, avoid dragging heavy objects across the deck. Promptly cleaning any spills will help prevent stains and maintain the deck’s pristine condition.

Common Mistakes to Avoid

Proper installation is key to ensuring the longevity of your deck. We emphasise the importance of accurate measurements and correct fastening techniques. Mistakes such as incorrect measurements can lead to wasted materials and added costs. At the same time, improper fastening can result in loose boards and structural issues.

Cost Considerations

Budgeting for your decking project is essential. We help you plan your budget by considering the costs of materials, tools, and labour. While composite decking may have a higher initial cost than wood, its long-term benefits and low maintenance requirements offer significant savings over time.


What is composite decking made of?

Composite decking is made from wood fibres and plastic, creating a durable and low-maintenance material.

How long does composite decking last?

Compound decking can last 25-30 years or more with proper care.

Can composite decking be installed over existing decks?

Yes, if the underlying structure is sound and level.

Is composite decking eco-friendly?

Many composite decking products are made from recycled materials, making them an environmentally friendly option.

How do you maintain composite decking?

Regular cleaning with mild detergent and water is recommended. Avoid using harsh chemicals or pressure washers.


At ALU Installations, we are committed to delivering exceptional composite decking installations. Following this comprehensive guide ensures a successful project from start to finish. Our attention to detail, from site preparation to finishing touches, guarantees a beautiful and durable deck, providing you with a perfect outdoor space for years to come.

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