Does Composite Decking Get Mouldy?

M. John
Learn Decking

Does composite decking get mouldy like wood decking? If you install a decking from Ultradecking in your home, you might wonder whether mould won’t attack your decking board. Like wood, mould can grow on your composite decking only if you fail to maintain it. Composite decking also contains traces of wood, making it susceptible to mould growth. However, to prevent your plastic wood decking from getting mouldy, maintaining it is important.

Why Composite Decking Can Get Mouldy

As mentioned earlier, composite decking can get mouldy if you don’t maintain it. A lot of people thought that mould could only attack wood decking. But mould can also grow on composite boards since it’s made from both wood and plastic. When dead leaves fall on your deck, you need to sweep the leaves away with a broom. But some people tend to ignore the leaves that fall on their decking and allow them to decay. If you fail to sweep the dead leaves away from your decking surface, the leaves will trap in moisture, making the surface of your decking moist or wet. 

Moisture can cause mould and mildew to grow on any surface. Mould can grow on the wall of a building, on fences, on wood and even composite decking. If the surface of your decking is dry, it will not be possible for mould or mildew to grow on it. Mould and mildew growth is only possible when moisture is present. When you let leaves stay on your decking for long, the leaves will trap in moisture, making your decking surface wet. The leaves might even start to decay from beneath. All these can cause mould and mildew to grow on your composite decking. And since composite decking also contains wood, it makes it susceptible to mould growth. 

But if you maintain your decking by sweeping the debris away from the surface, mould will not grow on it. What if your composite decking is mouldy? How can you get rid of the mould? 

How To Clean a Mouldy Decking

Can composite decking get mouldy

If your composite decking is mouldy, you can clean the decking and remove the mould. You can use natural substances like bicarbonate of soda and vinegar to kill the mould on the surface. While some people also use bleach to kill mould and mildew on their decking, you should avoid using bleach because it can cause more harm than good. Chlorine bleach or deck cleaners that contain sodium hypochlorite should not be used on composite decking. Here are steps in how to clean a mouldy composite decking.

 Step 1

The first step in cleaning mouldy composite decking is to clear the surface. Clear your decking by removing anything that is on its surface. Remove your couch, side table, potted plants, and other objects on your composite decking. Ensure that the decking surface is free before proceeding to the next step. 

Step 2

 After you have cleared your decking, rinse it. You can use a water hose to make the job easier. If you don’t have a hose, get a bucket full of water and pour the water on your decking. Use the water to rinse your decking so that some moulds will come off. 

Step 3

Get your vinegar and baking soda ready when you have finished rinsing your decking. Dilute the vinegar with water inside a bucket, then add the baking soda to the diluted vinegar. Mix and pour it on your composite decking. Ensure you pour the mixture on the affected part where you have the mould. Let the vinegar mixture stay for a while on your decking before you start scrubbing.

Step 4

Use a long bristle brush to scrub the entire decking and focus more on the mouldy area. Scrub the decking well so that the mould and mildew will come off. The vinegar and bicarbonate of soda will kill the mould, while scrubbing will remove the mould stains on your composite decking.

Step 5

When the mould stains are gone, use clean water to rinse your decking and let it dry. It would help let the decking dry well before returning the furniture and other objects.


Composite decking can get mouldy if you leave debris on its surface for a long time. However, to prevent mouldy decking, ensure you maintain it by sweeping it regularly.



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