How To Clean Composite Decking

Composite decking, renowned for its durability and low maintenance, has revolutionised outdoor living spaces.

Unlike traditional timber decking, it resists rotting and warping and doesn't require yearly treatments or painting.

However, to maximize its lifespan and maintain its aesthetic appeal, regular cleaning is essential.

This guide will walk you through the process of cleaning your composite decking efficiently, ensuring it remains attractive and safe throughout the year.

Recognising Common Issues with Composite Decking

Understanding and identifying common issues with composite decking is crucial for effective maintenance and longevity.

  • Algae Issues:

    • Common in wet conditions, causing the decking to become slippery and potentially damaging the material over time.
    • Cleaning is necessary to prevent algae accumulation.

  • Moss Growth:

    • Thrives in moist, mild conditions and often found in less trafficked areas of the decking.
    • Like algae, moss retains moisture, posing a risk to the decking's integrity.

  • Water Stains:

    • Occur in areas where water tends to pool, leading to unsightly marks.
    • Regular evaporation can minimise these stains, but they still require attention.

Key Takeaway: 💡 Regular inspection for algae, moss, and water stains is essential for maintaining composite decking. Prompt attention to these issues prevents long-term damage and preserves the decking's appearance and safety.


Step-by-Step Guide to Cleaning Composite Decking

A systematic approach to cleaning ensures your composite decking remains in pristine condition.

  • Initial Cleaning:

  • The first step in maintaining your composite decking is the removal of loose debris and surface dirt. This step is crucial for preventing the build-up of materials that can lead to more significant issues like staining, mold growth, or surface damage.

Removal of Loose Debris:

  • Begin by sweeping off leaves, twigs, and other organic matter that may have accumulated on the decking. Pay special attention to the gaps between the decking boards, as debris tends to accumulate in these spaces.
  • For areas under outdoor furniture or plant pots, lift or move these items to ensure a thorough cleaning.

Choosing the Right Brush:

  • Use a soft-bristle brush to sweep the decking. Soft bristles are effective in removing debris without causing any harm to the surface of your composite decking.
  • Brushes with harder bristles, while tempting for their scrubbing power, should be avoided as they can scratch and damage the protective coating of the composite material.

Gentle Approach:
  • When sweeping, use gentle, consistent strokes. This helps to effectively clear the surface without applying excessive pressure that could harm the decking.
  • If dealing with stubborn dirt or material stuck to the decking, avoid the temptation to scrub forcefully. Instead, this can be addressed during the deep cleaning process with appropriate cleaning solutions.

Choosing and Preparing the Right Cleaner:

  • Use a specially designed cleaner like the Owatrol Composite Decking Cleaner for tough dirt, algae, and mildew.
  • For a DIY solution, mix ammonia-free dishwashing liquid with warm water, or dilute apple cider vinegar with warm water.
Deep Cleaning Process:
  • Scrub the decking with the cleaner using a soft-bristled brush, following the grain of the decking.
  • Pay special attention to grubby areas like steps and around furniture, scrubbing multiple times if necessary.

Rinsing and Drying:

  • Rinse the decking with a hosepipe or buckets of water to remove any cleaning residue.
  • Use a sponge or towel to soak up standing water to prevent residue spots, then allow the decking to air dry completely.

Key Takeaway: 💡 A thorough yet gentle cleaning process, involving the right tools and cleaners, is crucial for maintaining the integrity and appearance of composite decking. Regular cleaning not only enhances its longevity but also keeps it safe and attractive.

Additional Cleaning Tips and FAQ

Addressing frequently asked questions and offering additional tips can further simplify the maintenance of your composite decking.

  • Using a Power Washer:

    • Safe for use on composite decking with a PSI not exceeding 3100.
    • Avoid on uncapped composite decking to prevent potential damage.

  • Selecting a Deck Cleaner:

    • Choose cleaners free from harsh chemicals like bleach to avoid damage or discoloration.
    • Ammonia-free dish soap or diluted apple cider vinegar can be effective alternatives.

  • Cleaning Frequency:

    • Perform a deep clean at least once a year, ideally after winter.
    • Regularly brush off dirt and debris to minimize damage.

  • Dealing with Damaged Decking and Subframe:

    • Replace structurally damaged decking boards to prevent exacerbating the issue.
    • Address any degradation in the subframe promptly to maintain the decking's foundation.


Maintaining your composite decking doesn't have to be a daunting task. By understanding common issues, following a systematic cleaning process, and adhering to our additional tips and FAQs, you can ensure your decking remains a pristine and enjoyable part of your outdoor living space for years to come.

If you're still planning your decking project, remember to explore our decking ideas and fitting guides for more insights.

Remember: Regular maintenance is key to the longevity and appearance of your composite decking, making it a worthwhile investment in your home's outdoor space.

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