How to Clean Composite Decking

Cleaning Tips to Keep Your Composite Deck Pristine

Composite decking is an excellent option for those desiring the aesthetic appeal of wooden decking but wanting to avoid the responsibility that comes with maintaining one. This beautiful and practical option combines the best of both worlds by offering the durability of synthetic materials and the natural charm of real wood. However, like all outdoor spaces, it still requires some level of care to keep it looking its best. 

Cleaning composite decking doesn't have to be a chore. With the right knowledge and a little elbow grease, you can restore your composite deck to its pristine glory.

The Importance of Regular Cleaning for Composite Decking

Differing from traditional wood decks, composite decking is crafted from a mixture of synthetic materials. While it's often resistant to issues like rot and warping, it's not immune to dirt, grime, and the occasional accidental BBQ spill. So, before you grab your deck brush, let's identify the common culprits:

• Weather: Rain, wind, and the relentless sun can leave behind a layer of dust, pollen, and mildew.
   
• Organic matter: Leaves, bird droppings, and spilled food can stain and attract unwanted critters.
   
• Mold and mildew: Shaded areas on your deck may harbor these unwelcome guests, thriving in damp conditions and manifesting as unsightly black or green patches.

Decks made from composite materials offer a much more relaxed approach to outdoor living. While they require less frequent maintenance than traditional wood, keeping them looking their best still involves some TLC. However, don't let "easier" fool you into thinking "never." Even though these boards won't splinter or warp as wood does, regular, thorough cleaning keeps them looking sharp for a long time.

A Guide to Cleaning Composite Decking

1) Pre-Cleaning Prep

No one starts a project without a clean slate, and cleaning your composite deck is no different. Before you dive into the cleaning process, start by giving those deck boards a once-over with a broom or leaf blower. This will get rid of loose dirt and debris like leaves and twigs.

Once the surface is free of debris, relocate any furniture, planters, and grills. Yes, everything needs to come off. Trust us—trying to clean around that patio set will only leave you with frustration and uneven results. When moving items, always lift and carry rather than dragging to avoid scratching your deck surface.

What you'll need for cleaning:

• A 5-gallon bucket
• Soft-bristle brush or deck brush (avoid metal bristles)
• Garden hose with spray nozzle
• Composite deck cleaner or mild dish soap
• Measuring cup for diluting cleaner
• Optional: pressure washer (1,500 PSI maximum with fan tip nozzle)
• Cotton towels or leaf blower for drying

2) Pre-Rinse with a Hose

Before applying any cleaning solution, give the entire surface a thorough rinse with a garden hose. This pre-rinse removes loose grime, pollen, and surface dirt, making your cleaning solution work more effectively on the stubborn stuff.

If you prefer using a pressure washer for rinsing, keep it at 1,500 PSI or lower with a fan tip nozzle. Hold the nozzle at least 6-8 inches from the deck surface and never leave the pressure washer sitting on the deck while it's running. And here's a critical tip: pressure washing is for rinsing only, not for scrubbing or applying cleaner. The high pressure can damage your composite boards if used improperly.

3) Applying Cleaner and Scrubbing

Now it's time to mix your cleaning solution. You have a few options here:

Option 1: Composite Deck Cleaner 

Follow the manufacturer's dilution instructions on the label. Typically, one gallon of diluted cleaner covers about 1,000 square feet of deck surface. Shake the bottle well before diluting.

Option 2: DIY Mild Soap Solution

Mix warm water with a few tablespoons of mild dish soap in your 5-gallon bucket. This works well for regular maintenance cleaning.

Option 3: For Mold and Mildew

Mix one part white vinegar with four parts water for a natural solution that tackles those green or black patches in shaded areas.

If eco-friendliness is as important to you as clean decking, look for biodegradable composite deck cleaners that'll do no harm to your plants or lawn while keeping things spick-and-span.

4) Work in Sections and Scrub

Here's where many DIYers make a mistake: they spray the entire deck with cleaner and then start scrubbing. Don't do this! Instead, divide your deck mentally into manageable sections—roughly 10-15 square feet at a time. Working in sections prevents the cleaner from drying before you can scrub and rinse, which would leave behind a stubborn white film.

The proper technique:

1. Apply your cleaning solution generously to one section
2. Let it sit on the surface for 30-60 seconds (but don't let it dry!)
3. Use your soft-bristle brush to scrub with firm downward pressure
4. Scrub both with the grain and across the grain to work the bristles into the deck's texture
5. Keep the section wet while scrubbing—add more cleaner if needed

Start at one end of the deck and work your way toward an exit point so you're not trapped or walking over freshly cleaned areas. Use a bucket or towel as a moveable marker to help you keep track of which sections you've completed—once everything is wet, it's surprisingly easy to lose your place.

5) Rinse Immediately and Thoroughly

This step is non-negotiable: rinse each section immediately after scrubbing. Seriously, don't scrub three sections and then rinse—do it one by one. Any cleaner left to dry on your deck will create a whitish residue that's a pain to remove.

Use your garden hose with good pressure to rinse in the direction of the board grain when possible. Make sure all soap and loosened dirt are completely washed away. If you're using a pressure washer for rinsing, remember: 1,500 PSI max, fan tip nozzle, and keep it moving.

6) Dry the Deck

Once you've rinsed the entire deck, take the time to dry the surface. This isn't just about preventing water spots—it's your quality control check. As you dry, you'll spot any areas you might have missed or stubborn stains that need a second pass.

Use cotton terry cloth towels, a sponge mop, or even a leaf blower to remove standing water, working in the direction of the grain when possible. Spot-clean any missed areas while the deck is still damp.

Common Cleaning Challenges

Composite decks are a breeze to maintain, but even they can throw you curveballs with stubborn stains and discoloration. We have a few tricks that can help address some of these challenges.

Stubborn stains: Try to clean spills and stains immediately, especially from food, oil, or greasy substances, as these might stain the deck. If sauce or grease has made its mark, whip out the dish soap and mix it into warm water for an easy DIY cleaning solution.

Mold and mildew: These unwelcome guests can appear on shaded areas of your deck. Mix one-part white vinegar with four parts water and scrub affected areas, followed by a thorough rinse.

Pollen and sap: Remove these sticky visitors with a mild dish soap solution and a gentle scrub. Avoid using harsh chemicals.

Winter woes: If you live in a snowy climate, remember to remove snow and ice promptly to prevent damage. When removing snow, use a plastic shovel with rounded edges to minimize the risk of scratching or damaging the composite surface.

Avoid harsh chemicals: Bleach, ammonia, and other harsh chemicals can damage your deck and fade the color. Opt for mild cleaners and natural solutions whenever possible.

What to Avoid When Cleaning Your Deck

• Bleach and chlorine-based cleaners: These can fade your deck's color and damage the material
• Harsh abrasives: Steel wool or abrasive scrub pads can scratch the surface
• Paint strippers and solvents: These are too aggressive for composite materials
• Pressure washing above 1,500 PSI: Higher pressure can damage the boards; always use a fan tip nozzle

If you've tried the appropriate cleaner twice and the stain persists, or if you're dealing with an unknown substance, contact your decking manufacturer's customer service for guidance before experimenting with stronger products.

Regular Preventative Care

To ensure your composite deck stays beautiful and functional, prioritize these simple preventative measures:

Minimize abrasion: Avoid dragging furniture across your deck, as it can scratch the surface. Always lift and move.

Reduce dirt accumulation: Use mats at entry points to minimize the amount of dirt tracked onto the deck.

Regular sweeping: Maintain a clean deck surface by sweeping regularly to prevent dirt and debris buildup.

Gentle rinse: A gentle hosing down is often all it takes to keep your deck looking fresh. Use a garden hose with a spray nozzle to blast away surface dirt and grime.

💡 Tip: Protect your investment: Accessories like deck post caps and fascia boards help shield your deck from the elements and preserve its clean, finished appearance. Explore our selection for a tailored finish.

Tackling Tough Stains and Specific Problems

Composite decks are a breeze to maintain, but even they can throw you curveballs with stubborn stains and discoloration. Here's how to handle the most common issues:

Food & Grease Stains

Try to clean spills immediately, especially from food, oil, or greasy substances. If sauce or grease has made its mark, mix dish soap with warm water and scrub with a soft brush. For set-in oil stains, apply the dish soap directly to the spot, let it sit for 5-10 minutes, then scrub and rinse thoroughly.

Mold and Mildew

These unwelcome guests can appear in shaded areas of your deck. Mix one part white vinegar with four parts water and scrub affected areas, followed by a thorough rinse. Let the solution sit for about 10 minutes before scrubbing for best results. Keep these areas well-ventilated and sweep regularly to prevent regrowth.

Pollen and Sap

Remove these sticky visitors with a mild dish soap solution and a gentle scrub. For sap, you may need to let the soapy water sit for a few minutes to break it down. Avoid using harsh chemicals or solvents, which can damage your deck's finish.

Rust Stains

If you notice rust marks from metal furniture or planters, use a rust remover that's specifically labeled as safe for composite materials. Always follow the product directions carefully and rinse completely. Better yet, prevent rust by using furniture pads or rust-resistant accessories.

Tannin Stains from Leaves

Those dark brownish stains from wet leaves sitting on your deck need prompt attention. Use a composite deck cleaner or oxygen-based cleaner, scrub thoroughly, and rinse. The key is not letting wet leaves pile up—sweep them off regularly, especially in fall.

Snow and Ice Removal

If you live in a snowy climate, remove snow promptly using a plastic shovel with rounded edges to minimize the risk of scratching the composite surface. For ice, use calcium chloride ice melt—never rock salt, which can damage your deck. Apply ice melt before storms when possible to prevent buildup.

Chemical Spills

For any chemical spills (paint, cleaners, pool chemicals, etc.), wipe them up immediately with a dry cloth. Don't let chemicals sit on your deck surface. If you're unsure how to clean a particular chemical, contact your decking manufacturer before attempting removal.

Regular Maintenance Matters

Making the time to clean your composite decking regularly is crucial for maintaining its inviting, vibrant, and durable qualities. Proper care and cleaning are indeed key to extending life and preserving the beauty of your composite deck.

However, if you're ready to take your deck to the next level, The Deck Store is your ultimate resource. Our expert guidance and premium products can help you achieve an outdoor oasis that truly reflects your style. Visit The Deck Store today and discover the endless possibilities for enhancing your outdoor living experience!