4 Disadvantages of Composite Decking

Composite decking is now available in just about every DIY store or Builders Merchant in many styles and colours. Timber decking is now widely seen as a last-resort cheap option which is very short-lived as it rots rapidly. However, before purchasing composite decking for your next decking installation you should first understand the disadvantages of composite decking.

The four disadvantages of composite decking are that it fades with sunlight, warps in hot weather, wears down in high-traffic areas, and, worst of all, causes timber subframes to rot and become unsafe. Interestingly, all these issues can be solved by choosing an aluminium decking board that has an integral gutter.

Read more on these problems:

  1. Composite Decking fades with sunlight
  2. Composite Decking Boards Warp in Hot Weather
  3. Composite Decking Wear Down in High Traffic Areas
  4. Causes Timber Subframes To Rot and Become Unsafe (The Most Concerning)

So, you might be asking, why is composite decking still sold? – well let’s go back to the beginning of the decking story and we’ll explain how all this came about…

Where the Decking Story Began:

The use of Timber Decking as a low-cost and effective way of making a clean and tidy outdoor seating area started back in the early 1980s. Inspired by similar uses on boats and marine areas, house owners started a new trend of using the same style of wooden decking planks for residential use.

The traditional paving-slab-style patio was costly and messy to install and had added complications when dealing with drains and ground that was not level.

The then-new idea of installing a timber deck over the top of all these irregularities and challenges meant a fast solution could be installed very quickly that was perfectly flat and looked very clean and neat. Not only that, but the relative cost was a fraction of the traditional patio installation.

However, despite ever-improving pressure treatment to help preserve the wooden decking boards, it quickly became clear that installations were rotting quickly. This not only made the installation and property look tired and shabby but also caused a safety risk as boards became weak.

Stop your decking rotting with Alupave decking

Over time a deeper problem became increasingly apparent. As the water dripped through the gaps between the decking and down onto the timber joists, they too started to rot. This meant that the whole structure could become unsafe, and typically would have to be replaced within a few years.

This unexpected expense still catches out many today who understandably try and make initial savings by opting for a cheaper wooden-type decking, only to find the hidden costs of maintenance and replacement come quicker and are greater than expected!

Does Composite Decking Solve these Issues?

Well, no. Composite decking only solves a fraction of these problems, leaving the more important problems with decking unsolved. These are now becoming increasingly apparent.

Composite (partially plastic) decking is generally made from a mixture of wood and plastic pulp (Sometimes called WPC = Wood Plastic Composite) and shaped into decking boards.

If you are considering using composite decking, then it’s no small investment and you want to make sure it will last!

Of course, most manufacturers will tell you it has a long lifespan and won’t rot etc…which is true. However, you should also be aware of the following significant issues that users are increasingly realising.

Below we have set out each of the four problems of composite decking, and what you can do to avoid them.

  1. Composite Decking fades with sunlight:

Many coloured plastic products will have issues with discolouration in the sunlight. This means your composite plastic decking area may begin to look tired and jaded after only a few years.

This can drag down the overall look of the property. However, powder-coated aluminium decking has a much longer-lasting colour fastness in nearly all climates and environments.  

  1. Composite Decking Boards Warp in Hot Weather:

As you’d expect, any plastic material will become softer when the weather gets hotter. Whilst it is waterproof, this means that composite plastic decking can warp and become distorted during hot weather and direct sunlight.

Using a structured but single-skin aluminium decking board means that the ventilated aluminium decking board will remain cooler and as it is aluminium it is unlikely to warp even in extreme temperatures.

  1. Composite Decking Wear Down in High Traffic Areas:

There is often a pattern on the surface of composite decking boards, but as you can imagine plastic is generally soft and wears down.

Even when plastic is mixed into a WPC (Wood Plastic Composite) compound, the surface is generally plastic. This means any higher traffic areas will show worn-down patches which look very unsightly.

So, it’s important you check that you check the wear resistance of the decking you are planning to use.

Alternatively, it’s a much better idea to use an aluminium decking system with an anti-wear design, which will stay looking the same for a long time.

  1. Causes Timber Subframes To Rot and Become Unsafe: (The Most Concerning)

Think about it, all the rain falling on your decking must go somewhere. – Yes, it drips down between the decking boards, which are supported on timber joists which in turn slowly rot!

This is a silent, unseen but very dangerous and costly decking mistake which you can easily avoid.

Waterproof decking should be secured to an expensive aluminium joist then, right? – Wrong. The costs of the aluminium joists are very high and completely unnecessary.

Simply buy the right decking system and you can save money by using traditional low-cost timber decking joists. It’s a far lower cost to use normal timber decking joists but also using a decking board that has an integral gutter. Overall, it’s a lower cost and will last far longer.

What to do with the Water from your Decking?

If you use a decking board that has an integral gutter as described above, then it’s easy. All the water will travel in the internal gutter to the end of your decking area. Then you can attach a Decking Gutter that allows you to route all the rainwater in any direction you wish. You an use Internal Decking Gutter Connectors or the External Decking Gutter Connectors to easily route the water around the sides of your decking. 

The added benefit is that you can harvest mineral-rich rainwater and reuse it for gardening or other home and gardening purposes.

Now, as users become increasingly aware of the problems with composite decking, they are also realising that all is not lost. All the issues with Composite decking can be solved by choosing aluminium decking. – Sound too simple? – it is simple… choose the right decking and you’ll eliminate all the problems of decking in one go.

Final Decking Tips:
In addition to all the above advantages of aluminium decking boards, you also get the benefit of fire safety that you get with metal decking. This makes aluminium decking an excellent option for high-rise balcony decking where an A1 fire-rated decking board is required. You should not use combustible materials for high rise construction. Also, the Aluminium decking is available in any RAL colour.

Need further advice on your Decking Projects?

Our Teams are very happy to assist on our Live Chat or you can email shop@clearamber.com where our super-friendly Teams will provide you with all the advice and support you require for your projects.

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Clear Amber Shop

Clear Amber Shop

Yes that right, Virginia. Composite decking and plastic decking can become very hot on the surface which may affect how much you can use your deck in summer. On the other hand, Aluminium Decking is very good at dissipating heat as it has excellent thermal conductivity properties.



We are facing west, out backyard deck can become extremely hot. I have heard that composite decking will be hotter to the touch than wood?

Clear Amber Shop Team

Clear Amber Shop Team

Thanks Molly. Yes, our Alupave Aluminium Decking would be great for that application. You are best to run the decking boards short to allow space for the drainage gutters. Most installers cut down on site to get accurate.
Remember you only need gutters on the draining edge and can use Endstop bar on all other sides if you wish.

Molly Fleming

Molly Fleming

Can the aluminum decking be used for a porch floor? Would there need to be a gap on the sides to allow for the drainage gutters

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