So you’ve got yourself the deck of your dreams. The last thing you want is to ruin it with a stain. Whether it’s red wine from that big party the other night, a build-up of mould after a bout of bad weather or a potted plant that’s left its mark, it’s important to get onto a stain on your composite decking as soon as possible.

Here’s what to do to make the mark disappear before it becomes a stain.

Common stains on composite decking

Composite decking is stain resistant but it’s not stain proof. If you barbecue or dine on your deck, it’s more likely to become stained by greasy oil, food or wine.

If it’s positioned under trees, your deck boards can become stained by fruits, tree sap and bird droppings, or leaves and pollen can cause mildew and mould.

If you don’t have special deck cleaner, bleach or strong chemicals on hand, a mixture of dish soap and warm water plus a bit of elbow grease will do the trick.

Tips for removing stains from composite decking boards

When you notice marks and blemishes on your composite decking boards, you should act quickly before the stain sets in. Here are some steps to help you get great results when removing stains from your decking boards.


  • Bucket
  • Sponge or soft cloth
  • Soft-bristled broom

Tip 1 – Use the right method for your stain type

When trying to remove marks from oils, grease and grime, wine, food, dirt, or bird droppings, start by sweeping off debris with a soft broom.

In most cases, your decking surface can be cleaned with a simple mixture of dish soap or dish detergent and warm water mixed in a bucket. Use a sponge and follow the direction of the grain of the decking boards. Use a hard-bristled broom to remove anything that’s left and use your garden hose to give the area a spray with fresh, cool water afterwards.

The best method to use for mildew, mould spots and algae stains is to use a solution made up of baking soda and vinegar to remove it. Use about half a litre of white vingear mixed with half a cup of baking soda in about 4 litres of warm water.

Tip 2 – Tackle tough stains with a pressure washer

If it’s a tough stain, you can use a pressure washer. However, to avoid damaging your deck, only use high-pressure washers with the nozzle at least 30cm away from the decking. You could also try using a sodium carbonate solution, like Selley’s sugar soap.

For rust and ink stains, use oxalic acid. It’s an organic compound that is readily available at hardware stores.

Tip 3 – Keep on top of maintenance issues

Move furniture and accessories such as pot plants and give your deck a brush off once a week to remove dust and debris. This also gives you the chance to inspect the boards for any issues which may cause permanent stains. Give your deck a sponge off every now and again and use the prevention methods listed below to keep stains at bay.

Here are some more great tips on how to clean and care for your composite decking.

Tip 4 – Deal with mould right away

Mould is another issue that often occurs on composite decking that may occur alongside stains, or even be mistaken for a stain.

The good news is that composite decking is much less impacted by mould in comparison to timber decking. Simple mould cleaning tips are all you need to deal with mould on a composite deck, whereas a timber deck can easily suffer rot from the same mould and mildew. Cleaning involves using warm soapy water and soft brush to remove the mould. For more stubborn mould, you may need to use more force or a small amount of mould cleaning solution.

The best way to avoid mould is to remove the source of moisture that has caused its growth. Make sure water is draining properly from your deck, that the gabs between boards aren’t clogged and can drain and put pots and plants on holders with feet so they don’t trap moisture.

Here are some more tips on how to deal with mould on your composite decking.

Ways to prevent future stains

Unlike a wood deck which would usually require sanding to remove a stubborn stain, a small amount of regular maintenance can keep composite decks looking like new for many years.

Here are some simple maintenance tips for homeowners to prevent damage and staining on composite decking.

  • Keep the appearance of your decking in good order by giving it a weekly sweep with a soft broom
  • Prevent potted plants from staining decking materials by using pot feet or stands
  • Use barbecue mats to prevent oil and grease stains from cooking
  • Use an outdoor rug under dining tables to catch any spills, but be sure to remove them for cleaning

For more ways to keep your decking looking brand new, read our Ultimate guide to clean and maintain your composite decking.

Top 3 Stain Removal Products for Composite Decking

While warm water and a gentle household detergent are normally enough to do the job, you might require something more for tougher stains. These cleaners can give you a professional-looking finish without compromising the integrity of your deck surface.

  1. Selley’s Sugar Soap Liquid

$4.60 from Woolworths

  1. Diggers Rust and Stain Cleaner

$32.75 from Bunnings Warehouse

  1. Oates Deck Scrub Brush

$43.39 from Bunnings Warehouse

While you should always follow the advice of your manufacturer when cleaning composite decking, it is engineered to be low maintenance and easily cleaned. You don’t need a variety of products to keep it looking good. Just some basic up-keep and an occasional wash.

To learn more about the advantages of composite decking, visit Brite Composite Decking Solutions.