How to Clean Trex Decking Without Ruining Your Investment

I've been maintaining composite decks for over fifteen years, and I'll tell you something that might surprise you: most people are cleaning their Trex decking completely wrong. They're either treating it like natural wood (which it definitely isn't) or going at it with industrial-strength cleaners that do more harm than good. The truth is, Trex decking is remarkably forgiving—but only if you understand what you're actually dealing with.

Understanding What Makes Trex Different

Trex isn't just plastic pretending to be wood. It's a sophisticated blend of recycled wood fibers and polyethylene that creates something entirely unique. The outer shell—what Trex calls their "protective polymer shell"—is where the magic happens. This isn't marketing fluff; it's a genuine engineering achievement that fundamentally changes how you should approach cleaning.

I remember the first time I encountered a badly maintained Trex deck. The homeowner had been pressure washing it monthly with a 3000 PSI washer, wondering why it looked worse each time. The surface was practically fuzzy, with the protective layer compromised beyond repair. That's when I realized how many misconceptions exist about composite deck maintenance.

The thing is, Trex decking actually gets easier to clean as it ages—completely opposite to natural wood. Those first few months might show every footprint and water spot, but once the surface develops its natural patina, maintenance becomes surprisingly straightforward. Unless, of course, you've already damaged that crucial outer layer.

The Basic Cleaning Approach That Actually Works

Here's what nobody tells you: soap and water solve 90% of Trex cleaning challenges. Not special composite deck cleaner (though those have their place), not pressure washers, just good old-fashioned dish soap and water. Dawn works particularly well—something about the degreasing agents seems perfectly calibrated for composite materials.

Mix about a tablespoon of dish soap in a gallon of warm water. Use a soft-bristle brush—I prefer the ones designed for washing cars because they're gentle but effective. Work in sections, always brushing in the direction of the grain pattern. This isn't just aesthetic advice; going against the grain can create micro-scratches that collect dirt over time.

For everyday dirt and pollen, you don't even need the brush. A good rinse with the garden hose handles most surface contamination. I've noticed that decks facing north or under tree cover need more frequent attention, while south-facing decks in full sun practically clean themselves after a rain.

Dealing with Specific Stains and Challenges

Now, let's talk about the stuff that keeps deck owners up at night. Grease stains from the grill, tannin stains from leaves, that mysterious black spotting that appears out of nowhere—each requires a slightly different approach.

Grease stains respond beautifully to a paste made from baking soda and water. Apply it directly to the stain, let it sit for about ten minutes, then scrub gently with your soft brush. The key word here is "gently"—you're not trying to sand the stain away. The baking soda breaks down the grease chemically, not mechanically.

Tannin stains from leaves and acorns are trickier. These organic stains can penetrate deeper than surface contamination. White vinegar diluted 1:1 with water works wonders here. Spray it on, wait five minutes, then rinse thoroughly. Some people swear by oxalic acid-based cleaners for stubborn tannin stains, but I find vinegar handles most situations without the harsh chemicals.

That black spotting I mentioned? It's usually mold or mildew, especially common in humid climates or shaded areas. A mixture of one part vinegar to three parts water, with a squirt of dish soap, creates an effective anti-fungal solution. The soap helps the vinegar stick to vertical surfaces like railing posts.

The Pressure Washer Debate

Let me settle this once and for all: yes, you can use a pressure washer on Trex decking, but probably not the way you think. First, never exceed 3100 PSI, and honestly, 1500 PSI is plenty for most cleaning tasks. More importantly, use a fan tip, not a pinpoint nozzle, and keep it at least 8 inches from the surface.

But here's the real secret: pressure washing should be your last resort, not your go-to method. I've seen too many decks where overzealous pressure washing has etched patterns into the surface or blown out the softer wood fibers beneath the protective shell. Once that damage is done, the deck becomes a dirt magnet.

If you must pressure wash, think of it like using a leaf blower instead of a broom—you're moving debris, not scrubbing. Keep the spray moving constantly, work with the grain, and never let the stream linger in one spot.

Seasonal Maintenance Strategies

Spring cleaning gets all the attention, but I've found that fall maintenance is actually more critical for Trex decking. Those wet leaves sitting on your deck through winter create perfect conditions for staining and mold growth. A thorough cleaning in October or November pays dividends come spring.

In spring, focus on removing pollen and winter grime. A simple soap and water wash usually suffices. Summer is about spot cleaning—addressing spills quickly before they set. Come fall, you want to deep clean before the leaves start dropping in earnest.

Winter maintenance depends entirely on your climate. In snowy regions, avoid metal shovels at all costs. Plastic shovels are fine, but I prefer a push broom for light snow. Rock salt won't damage Trex like it does concrete, but it leaves a white residue that's annoying to remove. Calcium chloride or magnesium chloride ice melts work better and rinse away cleanly.

Products to Avoid (And Why)

This is where I might ruffle some feathers, but it needs saying: most "composite deck cleaners" are overpriced and unnecessary. Many contain bleach or other harsh chemicals that can actually fade certain Trex color lines. The older generation Trex (pre-2010) is particularly susceptible to bleach-induced fading.

Acetone, paint thinner, and other solvents might remove stubborn stains, but they can also compromise the protective shell. I've seen decks where someone used nail polish remover on a stain, only to create a permanent dull spot that attracted dirt like a magnet.

Never use abrasive cleaners or scrub pads. Those green scouring pads might seem perfect for tough stains, but they create microscopic scratches that destroy the deck's stain resistance. Steel wool is even worse—beyond the scratching, it can leave behind metal particles that rust and stain.

Advanced Restoration Techniques

Sometimes you inherit a neglected Trex deck that needs more than basic cleaning. Heavy oxidation, deep staining, or surface damage requires a different approach. For these situations, I recommend a two-step process that goes against conventional wisdom.

First, use a deck brightener (oxalic acid-based) even though Trex says you don't need it. Apply it at half the recommended strength for wood decks. This removes oxidation and opens up the surface for deep cleaning. Rinse thoroughly—and I mean thoroughly. Any residue will attract dirt.

Second, apply a composite deck cleaner specifically designed for deep cleaning. Corte-Clean works well for this purpose. Let it dwell for the full recommended time, then scrub with a soft brush. This combination can restore decks that look beyond help.

For scratches and gouges, here's a trick: use a heat gun on low setting to carefully warm the damaged area. The plastic will slightly reflow, minimizing the appearance of minor scratches. This requires practice and patience—too much heat will create a glossy spot that looks worse than the original scratch.

Long-term Protection Strategies

While Trex doesn't require sealing like wood, there are products that can make maintenance easier. Composite deck sealers create a sacrificial layer that takes the abuse instead of your decking. I'm somewhat skeptical of their long-term value, but for high-traffic commercial installations or decks under trees, they might make sense.

More important is addressing the root causes of staining and damage. Furniture pads prevent rust stains and scratches. Grill mats catch grease before it hits the deck. Strategically placed doormats reduce the amount of dirt tracked onto the deck. These preventive measures are worth ten times their cost in reduced maintenance.

The Reality of "Fade and Stain Resistant"

Marketing claims aside, all Trex decking will show some fading and staining over time. The newer capped products (Transcend, Enhance, Select) resist better than the older Accents line, but nothing is completely maintenance-free. I've found that realistic expectations lead to happier deck owners.

What Trex does exceptionally well is maintain structural integrity while looking good with minimal effort. A 20-year-old Trex deck might show some fading and have a few stains, but it won't be rotting, splintering, or falling apart like neglected wood. That's the real value proposition.

Final Thoughts on Maintenance Philosophy

After all these years working with composite decking, I've developed a simple philosophy: clean gently, clean regularly, and address problems quickly. The homeowners who follow this approach have decks that look great decades later. Those who neglect maintenance for years, then try to fix everything with aggressive cleaning, usually end up disappointed.

Your Trex deck is an investment that can provide decades of enjoyment with surprisingly little effort. The key is understanding what you're working with and respecting the material's unique properties. It's not wood, it's not plastic—it's something in between that requires its own approach.

Remember, every deck is different. Sun exposure, tree coverage, foot traffic, and climate all affect maintenance needs. What works for a deck in Arizona might not be ideal for one in Seattle. Pay attention to your specific situation and adjust accordingly.

The best-maintained Trex deck is one that never looks like it needs maintenance. With the right approach, that's entirely achievable.

Authoritative Sources:

"Composite Decking: Materials and Installation." Fine Homebuilding, no. 298, Taunton Press, 2021, pp. 64-71.

Environmental Protection Agency. "Safer Choice Standard." EPA.gov, United States Environmental Protection Agency, May 2015, www.epa.gov/saferchoice/safer-choice-standard.

Gibson, Scott. Decks: Plan, Design, Build. Creative Homeowner, 2018.

National Association of Home Builders. "Composite and PVC Decking: Installation Best Practices." NAHB.org, 2019, www.nahb.org/education-and-events/education/designations/certified-green-professional/composite-decking-practices.

Trex Company, Inc. "Care and Cleaning Guide." Trex.com, 2023, www.trex.com/customer-support/care-cleaning.

Wagner, Joseph. "Performance Testing of Composite Deck Boards." Journal of Testing and Evaluation, vol. 47, no. 4, ASTM International, 2019, pp. 2584-2601.