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What plastic is used in composite decking?

By 10/09/2021September 13th, 2021Blog

When you’re looking for the best composite decking in South Africa, then you want to make sure that you’re getting the best quality of product. To that end, however, you might need to know what, exactly, is in your composite decking.

Having worked in carpentry and decking for over six decades, we at Timber Construction have a good understanding of what makes great composite decking and the complicated process of installation. Just take a look at the portfolio on our site to see why we’re qualified to tell you more about which plastic is used for composite decking and how you can make sure that you’re getting a better product.

Composite decking materials

Though there are different varieties available, the basics of composite decking are the same across the board. They all use a combination of real wood fibers alongside plastic, which helps them to maintain a realistic wood look and feel while making them more durable, long-lasting, and resistant to various environmental elements, like heat, moisture, and so on.

Composite decking has gone through many names through the years, including synthetic decking, recycled decking, and wood polymer composite decking. If you see a service offering decking by any of these names, just know that it is, indeed, offering composite decking.

How composite decking is made

When making composite decking, all of the raw materials are first put together and put through a machine called an extruder. What the extruder does is introduce extreme temperatures to melt the mix of wood fibres and plastics. The mix is then pressed through a “die” that shapes it into a traditional lumber shape. When the moulded mix cools, it can then be made into decking or used for any other application.

There are various styles that different composite decking producers can take during this process to further strengthen or enhance the materials, such as capping it with protective shells once the boards of the composite decking are fully shaped, which helps them last longer and resist damage, such as stains and scratches.

Which plastic is used for composite decking?

There are a few different types of composite decking that you can get. The materials that are used, for instance, can be broken down into three categories: polyethylene-based, polypropylene-based or non-wood plastics.

Polyethylene is perhaps the most widely used plastic in the world, right now. For instance, most packaging that uses plastic uses polyethylene, so much so that packaging accounts for roughly 70% of the world’s supply of the material. Polyethylene has a better resistance to wear and tear and is more resistant to lower temperatures. It’s also more elastic, making it easier to work with, which typically reduces the cost of polyethylene decking, as well.

While polyethylene might be a little cheaper, more composite decking manufacturers have been moving to work with polypropylene as the basis of their composite material. This is due to a few reasons. While polyethylene might be a little more resistant to general wear and tear, polypropylene is typically stronger and more resistant to expansion or compression. It’s also more durable, able to withstand the use of chemicals and high temperatures. This means that it’s used in much more industrial and high performance demanding applications than polyethylene, such as being used in the automobile industry as well as for food packaging of all kinds.

Non-wood plastics are far rarer than other types of composites for a few reasons. Primarily, they’re the one type of composite that tends to be more expensive than real wood, meaning that you need to set a high budget if you want to work with non-wood plastics.

Which type of composite decking should you get?

When looking at the types of composite decking out there, it’s important that you look at all the factors behind its construction, not just the material. Many teams that work with composites will agree that polypropylene-based composites tend to be a better investment for the reasons we’ve discussed.

Polypropylene affords composite decking better structural strength, as well as boards that don’t warp as easily due to the fact that it absorbs and retains less heat. Furthermore, it also allows for less sagging and flex around the joints, which improves the structural integrity of the decking overall. However, it’s worth noting that the type of wood that the plastic is blended with will also play a significant role in the properties of the decking.

Another of the other properties that determine the quality of the decking is whether it’s uncapped or capped. Composite boards can be capped with plastics. The outer surfaces of the boards are coated in this material because it affords it extra protection, such as: preventing stains, stopping the boards from absorbing water, and protecting against UV light. This can be useful for any decking that is to be used in areas around water or that might be exposed to rain.

Yet another difference in decking is where or not it is hollow or solid. Hollow composite boards have holes inside them, which is primarily done to reduce the weight of the boards. Aside from making it easier to expand and contract, which can be useful in outdoor environments, it also reduces the overall cost of the decking. Meanwhile, solid decking is heavier and somewhat more expensive, but it’s also stronger and tends to have less potential for flex.

Get the best composite decking in South Africa

Now that you hopefully know a little more about which plastic is used for composite decking and the different varieties available, you might want to get started with your project. To that end, get in touch with the team at Timber Construction in South Africa today. Tell us about your plans and we can work with you to get the project started as soon as possible.

When you work with Timber Construction, you can ensure that you’re relying on a professional opinion that has the experience and expertise to help you make the choices best suited to your needs. We bring with us the highest carpentry qualifications available in the UK, where we first started working.