How to Clean Trex Decking

Trex decking is a top choice for homeowners who want a low-maintenance, long-lasting outdoor space. But low maintenance doesn’t mean no maintenance. Like anything exposed to the elements year-round, Trex decking still needs occasional cleaning to look its best and last as long as it should.

Whether you’re dealing with dirt, mould, or stains, here’s everything you need to know about cleaning Trex decking the right way.

Related Article: How to Resurface a Deck with Trex

Why Trex Decking Is Worth Maintaining

Trex decking is made from composite materials—wood fibres and recycled plastic—so it doesn’t rot, splinter, or warp like traditional wood. It’s resistant to insects, fading, and most weather conditions. But that doesn’t make it bulletproof.

Pollen, dirt, mildew, food spills, and even barbecue grease can all build up on the surface over time. Regular cleaning protects your investment, keeps your deck safe to walk on, and maintains its curb appeal.

Neglecting your Trex deck won’t just make it look weathered. Built-up grime can make it slippery, especially after rain. Mould can spread if not cleaned. And stains can set in, becoming harder to remove later. Routine care keeps small problems from becoming expensive repairs.

Basic Tools You’ll Need

Cleaning Trex doesn’t require expensive equipment. You’ll just need:

A soft-bristle brush or broom
Bucket of warm water
Mild dish soap or a composite deck cleaner (approved by Trex)
Garden hose with spray nozzle
Optional: pressure washer (max 3100 psi, fan tip)

Avoid harsh chemicals like bleach or chlorine. They can damage the surface and void your Trex warranty. If you’re unsure about a product, always test it in a small, hidden area first or consult with a professional.

Related Article: How to Clean Composite Decking

Step-by-Step Guide to Cleaning Trex Decking

Cleaning your Trex deck doesn’t need to be complicated. With the right tools and a bit of time, you can restore your deck’s appearance and performance. Here’s how to do it right, step by step.

1. Clear the Surface

Start by removing all furniture, planters, and accessories. Sweep the deck to get rid of loose dirt, leaves, and debris. Pay extra attention to corners, gaps, and edges where dirt tends to collect.

2. Rinse Thoroughly

Use a garden hose or pressure washer on a low setting to rinse the surface. This helps loosen any stuck-on grime and prevents you from scrubbing dirt deeper into the deck. If using a pressure washer, make sure you use a fan tip and keep it at least 8 inches from the surface.

3. Scrub with Soap Solution

Mix mild dish soap with warm water in a bucket. Dip your brush into the soapy water and gently scrub in the direction of the grain. Focus on high-traffic areas and spots with visible stains or build-up. For textured surfaces, make sure to reach into the grooves where dirt can hide.

For deeper cleans, use a Trex-approved composite deck cleaner. Follow the product instructions carefully, and allow the cleaner to sit on the surface for the recommended amount of time before rinsing.

4. Rinse Again

Once you’ve scrubbed all areas, rinse the deck thoroughly to remove all soap and residue. Leaving soap behind can create a slippery surface and attract more dirt.

5. Let It Dry

Allow the deck to air dry completely before putting furniture or rugs back in place. This helps prevent mildew growth and keeps the surface looking clean. On a sunny day, most decks dry within a few hours.

How Often Should You Clean Trex Decking?

Twice a year is a good rule of thumb—once in the spring to wash away winter grime and again in the fall to prep for colder months. If your deck is under trees, used frequently for grilling, or prone to dampness, you may need to clean it more often.

In high-use settings or shady, damp areas, consider monthly spot cleaning to prevent buildup of mould or debris. Even a light sweep and rinse can go a long way.

Dealing with Specific Problems

Even with regular care, your Trex deck may occasionally face specific issues like stains, mildew, or weather damage. Knowing how to handle these quickly and safely can extend your deck’s life and keep it looking great. Here’s how to deal with the most common problems:

Mould or Mildew

Use a composite deck cleaner specifically designed to remove mould and mildew. Scrub the affected area gently, rinse thoroughly, and dry completely. Don’t use bleach or ammonia—they may cause discolouration.

Oil and Grease Stains

Act fast. The longer oil sits, the harder it is to remove. Use warm, soapy water and a degreasing composite-safe cleaner. Avoid wire brushes—they’ll scratch the surface.

Rust or Leaf Stains

Use a soft brush with white vinegar or a cleaner approved for rust stains on composite decking. Don’t use bleach—it can fade the colour.

Ice and Snow

Use a plastic shovel, not metal. For ice, calcium chloride (safe for composite decks) works well. Sweep up any leftover residue in the spring.

What to Avoid When Cleaning Trex

Pressure washing with high PSI or a narrow tip: Too much pressure can damage the surface.
Using bleach, chlorine, or acetone: These chemicals can cause permanent discolouration.
Letting debris accumulate: Trapped moisture under leaves or rugs can encourage mould growth.
Not rinsing thoroughly: Soap residue can cause the deck to become slippery or sticky.
Skipping routine care: Putting it off only makes the job harder later.

Related Article: Top Tips for Waterproofing Your Deck

Extra Tips to Keep Your Trex Deck in Top Shape

Place mats under grills and planters to catch spills and moisture.
Don’t use rubber-backed rugs—they can leave marks on composite decking.
Trim nearby trees and bushes to reduce debris.
Clean up spills (especially greasy ones) as soon as they happen.
Keep your deck shaded but ventilated—airflow helps prevent moisture buildup.
Inspect your deck seasonally for any signs of damage, wear, or mildew.

Related Article: When Is the Best Time to Install a Deck?

Trust the Experts at Green Side Up Contracting

At Green Side Up, we don’t just build decks—we help you keep them looking their best. With over 24 years of experience and 11 HomeStars awards, we’re trusted by homeowners across the GTA and York Region for high-quality outdoor construction and care.

We specialize in using premium materials like Trex, and we know how to care for them the right way. From deck builds to seasonal maintenance, we’re equipped to handle it all.

Whether you’re looking for seasonal maintenance advice or a full deck renovation, we’re here to help. Our work is backed by years of expertise, a commitment to quality, and a customer-first approach that puts your outdoor living goals at the centre of everything we do.

Need Help With Your Deck?

If your Trex deck needs more than a seasonal cleaning or if you’re thinking about building one, reach out to Green Side Up Contracting. We offer custom decking solutions that are built to last—and look good doing it.

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