How to Clean Composite Decking: A Complete Australian Guide
Composite decking is one of the lowest-maintenance outdoor surfaces available. A quick weekly sweep and a full wash twice a year keep most decks looking close to new. Unlike timber, composite never needs sanding, oiling, or sealing, which is the main reason homeowners choose it.
In projects located in the humid coastal regions of Queensland, if floor gaps are not kept clear, mold can return within a single rainy season. A quarterly wash with soapy water and a firm sweep of the gaps prevents almost all of it. The method below works for any capped composite board and takes one afternoon.
This guide covers the five-step cleaning process, a problem-by-problem stain reference, cleaners to avoid, and how often to clean in Australian conditions.
Table of Contents
How Do You Clean Composite Decking in Five Steps?
A full composite deck clean takes one afternoon and needs only a broom, a soft to medium nylon brush, a bucket of warm soapy water, and a garden hose. Follow these five steps in order.
Step 1: Clear the deck. Remove all furniture, pots, and planters so you can reach every board. Sweep off leaves, dirt, and debris, and clear the board gaps with a stiff broom or a putty knife. Protect nearby plants that may be sensitive to cleaning runoff.
Step 2: Prepare the cleaner. Fill a 10-litre bucket with warm water and a composite deck cleaner or mild soap. Keep a spray bottle for spot treating individual stains and a soft bristle brush within reach. Avoid harsh solvents and bleach-based products, which can damage the cap layer.
Step 3: Work in sections. Clean one small section at a time so the cleaner does not dry before you scrub. Apply the diluted cleaner and leave it for 30 to 60 seconds. Clean in the morning or late afternoon to avoid the cleaner evaporating in direct sun.
Step 4: Scrub with the grain. Use a soft to medium nylon brush and scrub along the grain of the board first, then across. The Ultra Grain texture on EVODEK boards holds dirt in the grain channels, so scrubbing with the grain lifts it most effectively. Give edges and board ends extra attention.
Step 5: Rinse thoroughly. Rinse each section with a garden hose before the cleaner dries. Remove standing water with a sponge mop, then let the boards air dry. Repeat section by section until the whole deck is done.
How Do You Remove Specific Stains from Composite Decking?
The seven most common composite deck stains each need a specific method, from immediate wiping for food spills to diluted vinegar for hard water marks. The table below covers each stain type found in Australian homes and the safest way to remove it.
| Stain type | How to remove it | Note |
| Food and drink spills | Wipe immediately, then wash with warm soapy water | Act fast to prevent setting |
| Grease and oil | Blot with paper towel, then use a degreasing dish soap | Common near BBQ areas |
| Mould and mildew | Soapy water and a nylon brush; rinse well | Keep gaps clear to prevent return |
| Hard water marks | White vinegar diluted 1:1 with water, then rinse | From sprinklers or tank water |
| Tannin from leaves | Composite deck cleaner; fades over several weeks | Common under eucalyptus and gum trees |
| Ice and frost | Plastic shovel only, never metal edged tools | Metal scratches the cap layer |
| Rust marks | Mild cleaner or diluted vinegar, then rinse | From metal furniture feet |
Which Cleaning Methods Damage Composite Decking?
Three common cleaning mistakes damage the protective cap layer that keeps composite decking looking good: abrasive tools, harsh chemicals, and high pressure washing. Avoiding these protects your warranty and the board surface.
Avoid metal tools and wire brushes. Steel wool, wire brushes, and metal edged scrapers scratch the cap layer and expose the core. Use only soft to medium nylon brushes and plastic shovels.
Avoid bleach and strong solvents. Undiluted bleach, acetone, and acid based cleaners can discolour the cap and void warranty coverage. A composite deck cleaner or mild soap handles almost all cleaning safely.
Limit pressure washer force. A pressure washer can be used carefully but should stay below 10,000 kPa (around 1,500 PSI) with a fan tip held at least 200 mm from the surface. Always spray with the grain. Too much pressure erodes the surface and can leave permanent marks.
How Often Should You Clean Composite Decking in Australia?
Composite decking needs a full clean twice a year, ideally in early autumn (March) and early spring (September), plus a weekly sweep to remove debris. Decks in humid or coastal regions may need quarterly washing to prevent mould.
Clean the deck when the temperature is above 13°C so the cleaner works properly and dries evenly. A quick clean is also worthwhile after storms, heavy leaf fall, or a period of the deck being covered by sand, mud, or debris. Regular small efforts prevent the buildup that makes deep cleaning harder.
Keeping board gaps clear is the single most important habit for long term deck health. Blocked gaps trap moisture, which encourages mould and interferes with drainage and ventilation. For more on why this matters, see our guide on why composite decking lasts longer than wood.
How to Keep EVODEK Composite Decking Looking New
EVODEK CPD-05 and CPD-08 boards are fully capped with an Ultra Grain surface and carry a 25 year residential warranty. The capping resists staining and moisture, but a few simple habits keep the boards looking their best for the full warranty period.
Sweep regularly to remove leaves, pollen, and dirt before they stain. Clean spills quickly, especially grease near barbecue areas. Remove mould as soon as it appears. When doing nearby building work with cement, render, or paint, cover the deck to protect the surface.
If you are still deciding on a board colour or want to see the Ultra Grain texture in person, use the EVODEK Colour Selector or order free samples. For a broader look at choosing a durable board, see what is the best composite decking in Australia.
Conclusion
Cleaning composite decking is a simple twice yearly job: clear the deck, apply a mild cleaner, scrub with the grain using a nylon brush, and rinse. Avoid metal tools, bleach, and excessive pressure washing to protect the cap layer. Keep board gaps clear and sweep weekly to prevent mould and staining, especially in humid or coastal Australian climates.
EVODEK capped composite decking makes this routine even easier because the sealed surface resists stains and moisture. Use the EVODEK Colour Selector to preview colours, order free samples to compare, or request a quote from your nearest Australian distributor.
FAQ
Can I use a pressure washer on composite decking?
Yes, but keep the pressure below 10,000 kPa (around 1,500 PSI) and hold a fan tip nozzle at least 200 mm from the surface. Always spray with the grain. Excessive pressure can erode the cap layer and leave permanent marks. A garden hose is safer for routine rinsing.
Can I clean composite decking with soap and water?
Yes. Warm water with a mild soap or a dedicated composite deck cleaner handles almost all routine cleaning. Mix the soap into warm water rather than applying it neat. Avoid bleach and strong solvents, which can discolour the cap layer.
How do I remove mould from composite decking?
Rinse the affected area, then scrub with warm soapy water and a soft to medium nylon brush. Rinse thoroughly afterwards. Keeping board gaps clear of leaves and debris prevents mould from returning, which is especially important in humid and coastal Australian regions.
How often should I clean my composite deck?
Clean composite decking fully twice a year, in early autumn and early spring, with a weekly sweep in between. Humid or coastal decks may need quarterly washing. Clean after storms or heavy leaf fall, and always when the temperature is above 13°C.
Will composite decking fade or stain over time?
Capped composite resists staining and fading far better than uncapped boards. Some gradual UV colour change occurs over the first 12 to 24 months before stabilising. Regular cleaning keeps the surface looking its best. Grey tones show the least visible change over time.
What should I not use to clean composite decking?
Avoid steel wool, wire brushes, metal scrapers, undiluted bleach, and acid based cleaners. These damage the protective cap layer and can void your warranty. Use soft to medium nylon brushes, plastic shovels for ice, and mild soap or a composite deck cleaner.
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