How to Properly Clean a Composite Deck in 5 Easy Steps

Homeowners choose composite decking for its durability, long lifespan and stylish appearance. It instantly enhances outdoor areas, adds value to your property and offers an excellent long-term investment with minimal fuss. With regular maintenance and proper care, composite decks will continue to look great and perform well for many years.

Unlike traditional timber decks, composite decking is made from a blend of wood fibres and recycled plastics. This hybrid composition is designed to reduce maintenance, saving you time on sanding, staining and oiling. However, it still requires routine cleaning to protect it from dirt, mould, and weather-related damage.

If you are unsure where to begin, you are not alone. Cleaning composite decking is straightforward once you know what to do. The following is a handy guide to help you through the process step by step. 

This article explains how to clean composite decking effectively so you can protect your investment and enjoy a beautiful outdoor space year-round.

What is Composite Decking Made of?

Sydney composite decking combines wood fibres and plastic materials, making it stronger and longer lasting than standard timber. With proper care, it can last up to 50 years. It replicates the natural look of timber without the heavy maintenance, making it a popular, low-maintenance solution for Australian homes and commercial properties.

There are three main types of composite decking:

Solid composite deck boards

Dense and durable, solid boards resemble natural timber and are ideal for high-traffic areas such as pool decks, pathways and outdoor dining spaces. However, they can expand and contract in extreme temperatures.

Hollow boards composite deck boards

Lightweight and economical, hollow boards require end caps for support. They are more prone to damage and don’t look as natural as solid boards, making them better suited to light-use areas.

Capped boards composite deck boards

These boards feature a protective polymer shell that improves resistance to stains, scratches and fading. They are a stylish, long-lasting choice for outdoor living areas, patios and pool surrounds.

Benefits of Composite Decking

• Highly durable
• Low maintenance
• Attractive appearance
• Slip and weather resistant
• Adds value to your property

Drawbacks to Consider

• Higher upfront cost
• Limited refinishing options
• Can expand or contract in harsh climates
• Not easily recyclable

Even though composite decking is resilient, it still needs to be cleaned regularly to prevent mould, mildew, stains and weather damage. With consistent maintenance, you can protect its surface and extend its lifespan.

Why Cleaning and Sealing Matters

Australia’s harsh climate can take a toll on outdoor surfaces. Sun exposure, rain, humidity and debris can all impact the appearance and integrity of your deck over time. 

Regular cleaning and sealing prevents damage, protects your investment and keeps your decking safe and slip-resistant. Well-maintained composite decks from quality decking suppliers can last 30–50 years when properly cared for.

How to Clean a Composite Deck: Step-by-Step

Step 1: Gather Your Cleaning Materials

You will need:

• A pH-neutral or mild composite deck cleaner
• Soft-bristle brush
• Garden hose
• UV and moisture-resistant deck sealant
• Paint roller or brush
• Gloves and safety goggles

You can find these products at most hardware stores. If you are unsure which cleaner or sealant suits your deck, ask your composite deck board specialist for advice.

Step 2: Clear the Area

Remove furniture, plants, mats and outdoor items from the deck. Sweep away loose debris such as leaves, dirt and pollen using a broom or blower. This helps prevent debris from getting trapped during cleaning and ensures even sealing later.

Inspect your deck for signs of damage, such as cracks or loose fixings, and address issues before cleaning.

Step 3: Clean the Surface

Apply your composite decking cleaner and scrub gently with a soft-bristle brush. Test a small section first to ensure compatibility. Work in sections and give extra attention to stained or mouldy areas. Avoid harsh chemicals or metal brushes, as these can damage the surface.

Rinse thoroughly with a hose. If using a pressure washer, use a low setting and keep the nozzle at least 30cm from the surface to prevent damage.

Step 4: Use a High Quality Deck Sealant

Once the deck is completely dry, apply a quality composite deck sealant to protect against moisture, UV damage and stains. Use a paint roller or brush for even coverage. Follow the drying time recommended by the manufacturer. If you have a large deck, hiring a professional can save time and ensure a flawless result.

Step 5: Maintain Regularly

Clean your deck at least once a year and more often if it is exposed to heavy use, trees or wet weather. Avoid placing rubber-backed mats or using harsh cleaners. Regular inspections can help you spot issues early and avoid costly repairs.