Look, we get it. You opted for composite decking because you were sold on the fact that it was “maintenance-free”. And while that's largely true in contrast to timber, it's not like you can forget about your deck altogether. The best composite needs some TLC to maintain its looks.

Our Perth climate is a tough one; our incessant sun, sporadic heavy rain and that dusty stuff just lying around make for some wearisome conditions on your deck year in, year out.

No matter whether you have Trex or Millboard, reading the rest of this article will ensure it is clean for many years to come.

So, let’s take a closer look at the down and dirty of the composite deck cleaning Perth homeowners need to know.

So let's dive into the nitty-gritty of composite deck cleaning Perth homeowners need to know.

Why Bother Cleaning Composite Decking?

Fair question. After all, you didn’t decide on composite so that you would be scrubbing it every weekend, did you?

After all, while composite decking is designed to resist rotting and warping due to it’s weather-resistant nature, it can still become dirty and stained with leaves. Perth's climate is particularly challenging.

“In the summer we can experience UV index levels of 11-12 and 145 mm of rainfall at its peak in July,” the Australian Bureau of Meteorology explains. The WA Department of Health says this is the perfect scenario for the growth of mould spores.

Mould can cause respiratory symptoms, particularly in asthma and allergy sufferers, health authorities warn. Routine sanitation helps keep spore counts in check.

And most composite decking warranties can be voided if you don’t maintain it according to the manufacturer’s instructions. Nobody wants that.

The Basics: What You'll Need

Before I give you brand-specific advice, let’s talk about your cleaning arsenal.

Here’s what works for most composite decking:

A good broom (stiff bristles work best)
Garden hose with spray nozzle
Soft-bristle brush or deck brush
Bucket
Gentle dish soap or specific composite deck cleaner
White vinegar (your secret weapon)
Baking soda for stubborn stains

Hmm, and what is not on that list? Aggressive pressure washers, metal brushes and strong chemicals. We'll get to why later.

General Cleaning Method for Composite Decks

Okay, so where do you begin with your regular maintenance? This is the case for most composite decking – it’s something you’ll need to do every few weeks (during summer in Perth, less often in winter).

First, sweep: Get rid of leaves, dirt and spiderwebs. Boring but necessary.
Hose it off: Get rid of surface dirt with a good spray setting. Nothing too aggressive.
Soap and scrub: Mix warm water with dish soap, then scrub sections in the direction of the grain.
Rinse well: Dirt sticks to soap, so wash all of it off.

That's it for regular cleaning. Easy.

How to Clean Trex Decking: The Complete Method

Now let's talk about Trex specifically. As Trex PRO certified installers, there are some things we’ve picked up about how to maintain these decking projects.

If you are thinking about using Trex on your home, be sure to take a look at our full guide on Trex composite decking in Perth.

Trex is coated with a protective shell that will never stain or attract mould. But that doesn’t mean the iPhone is invincible.

Regular Maintenance

Vacuum regularly to prevent staining from tannins in leaves of gums.
Clean monthly with soap and water (dish soap is okay – don’t waste money on special cleaners).

Tougher Stains

Got stubborn marks? Here's what works:

Organic stains: One part vinegar to one part water. Let it remain for 10-15 minutes and then scour.
Grease marks: A paste of baking soda (mix with a little water) and scrub.
Mould spots: A solution of one part bleach to three parts water. Test on an inconspicuous area first, as some of the colours for Trex can be finicky.

What NOT to Do

Never, ever use acetone, straight bleach or deck “strippers”—they will damage the protective cap layer. Pressure washers are risky too. If you need to keep them under 3100 psi, fine, but a garden hose and elbow grease is truly safer.

What NOT to Do with Trex

Never apply acetone, full-strength chlorine bleach or a deck “stripper”. These can erode the protective cap layer that makes Trex so strong.

The jury is also very much still in session for pressure washers. The company says it’s allowed to use one, but at less than 3100 psi and with the spray nozzle held at least 20 cm away from the deck surface.

Honestly though? It’s no more effective and pales in comparison to a garden hose with a little elbow grease.

Millboard Cleaning Guide: Keeping It Pristine

Millboard is a different animal – it's more plastic than wood fibre. The non-porous surface also means spills sit on top rather than penetrate, which makes cleaning easier but can be slick when wet.

Regular Care:

Sweep weekly (dirt doesn’t adhere the way it does on Trex).
Clean monthly with a good scrub using warm, soapy water and a stiff-bristled brush.
Focus extra on textured grain details where dirt can hide.
After rinsing, squeegee off the standing water.

Specific Stains:

Red wine, coffee, food: it’s quick action with soapy water. They don’t pierce, so they’re simple.
Mould or algae: 50 ml bleach to a bucket of water. Use, wait 10 minutes, scrub, rinse. Millboard handles bleach well.
Oil and grease: Spray the deck with a spray-on deck degreaser purchased at the hardware store.

Millboard's Quirk

A chalky look can be the result of abrasive cleaners or hard water deposits. Fix it with water-vinegar (50/50 mix). Mop on, leave it for about a second and then rinse.

Common Mistakes That'll Wreck Your Composite Deck

Which brings us to what not to do, all of which is strangely popular.

Mistake #1: The Wire Brush

Somebody will swear by a wire brush to scrub away particularly challenging stains. That person is wrong.

Wire brushes scratch the protective shell that seal in composite decking, leading to open pores and rough patches where dirt can collect readily. Use nylon-bristle brushes only.

Mistake #2: Letting Stuff Sit

That pot plant that died, the firewood you have stacked and stored for ages, everything the kids left in one spot for a few weeks – they’re all choking on moisture underneath.

This is an ideal environment for mould and can also be discoloured. Move things around regularly.

Mistake 3: Using The Wrong Cleaners

Anything containing petroleum distillates, mineral spirits or harsh solvents is a no. Those “miracle” deck cleaners that supposedly breathe life back into wood?

Those are made for wood, not composite, and are more likely to damage than renew it.

Mistake #4: Ignoring the Gaps

The gaps between your deck boards are also worth the attention. Debris gets in there, and moisture becomes trapped, which helps spur the growth of mould.

Scrape between your deck boards with a putty knife every few months.

Mistake #5: Overdoing it on Pressure Washing

We’ve already been through this, but let’s go ahead and revisit it. Excess pressure can ruin the texture on the surface of your composite decking by causing rough, fuzzy or cloudy patches and possibly breaking down the fibres in your decking, which can void its manufacturer’s warranty.

Avoid using it, but if you have no choice, keep the pressure low and the nozzle constantly in motion.

Seasonal Maintenance Tips for Perth Conditions

Both gravel driveways and concrete driveways in Perth take some serious punishment from the weather, so use these tips to adapt your cleaning routine.

Summer: Brush two times per week to get rid of the fine dust. Hose down quickly to prevent staining after barbecues. Check shaded corners for mould.
In the fall: Don’t leave a leaf pile out too long, or tannin stains will follow. Organise and deep clean before the winter rains come.
Winter: Monthly checks for mould are adequate. Our hot, humid environment is the perfect place for spores to proliferate.
Spring: Proper deep clean time. Tackle any stains now, ahead of summer entertaining.

Follow that seasonal rhythm, and your deck will be in tip-top shape all year without requiring heroic cleaning efforts.

When to Call in the Professionals

But DIY cleaning won’t always cut it, and that’s O.K.

If you have broad-ranging discolouration that just doesn’t seem to be coming off as well as you think it should, invest in professional plastic deck cleaning Perth services. We have access to commercial-grade cleaners that are composite-safe but pack more punch than household products.

See some structural problems during cleaning? Popped fasteners, loose boards or movement to the deck structure require professional eyes. In our climate little problems grow really, really fast, and catching them early saves money down the track.

On the other hand, if you’re getting major fading or discolouration in large areas, get an expert to weigh in. What may look like stubborn dirt could actually be UV damage or a manufacturing defect that’s covered by warranty.

We’ve seen our fair share of trex decks and Millboard decks in Perth here at Eco Carpentry, so we know what to look (and listen) for, and can fill you in.

Keep It Simple, Keep It Clean

When it comes to keeping a composite deck clean, you don’t have to make it a big job. Whether you’re rocking Trex decking or Millboard, it should just take a regular sweep and an occasional wash-down to keep things looking good.

The key is consistency. A little and often is better than leaving it for months at a stretch and then facing a mammoth cleaning project. Your deck is a lifestyle investment, and taking care of it can ensure you enjoy it for many years without any drama.

Do you have questions about your composite decking scenarios? Contact us at Eco Carpentry. We’ve built and maintained a fair few decks throughout Perth and, as such, have seen it all. We're always happy to help.

Now go out there and enjoy the thing – you deserve it after all that cleaning!

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How to clean your composite deck: step-by-step guide