What is Composite Decking Made of?


It would be pretty simple to lump every type of composite decking into the same basic category – aka “not wood.” However, a closer look reveals that the actual ingredients that go into producing one brand of composite decking will often vary greatly from another.

It’s like comparing Cheerios and Wheaties. Sure, both are in the same category – cereal – but they’re made from entirely different stuff. Cheerios are made from Whole Grain Oats. Wheaties are made from Whole Grain Wheat. While the main ingredient in both cereals is good for you, each one promises to deliver a slightly different combination of benefits. It’s the same way with composite decking.

The Good, Better, Best of Composite Decks

Most composite decking options are going to deliver better results than traditional pressure treated (PT) wood decking. However, a closer look at how different types of composites are made – and what they are made from – can help consumers determine which one is right for them.

What Are the Primary Ingredients of Composite Decking?

The primary ingredients of all composite decking are plastic and wood. Many times, both the plastic and the wood used to make composite decking have been sourced from recycled materials, making composite decking a particularly eco-friendly choice.

For example, DuraLife composite decking is made with up to 90% recycled content sourced from both post-industrial and post-consumer material. All of the raw material - the sawdust, wood chips and wood fiber – used to create the hardwood “flour” that DuraLife mixes into its composites is sourced from within 500 miles of its manufacturing facility in Biddeford, Maine.

How Are Composite Decking Boards Made?

Composite decking is made using a co-extrusion process where all of the raw materials are combined and then introduced into an extruder that melts the mixture and forces it through a “die” to form the dimensional lumber shape. While all composites are designed to hold up over time better than traditional lumber, some manufacturers go even further. For example, DuraLife decking is produced using a unique co-extrusion process that places a tough, capped composite polypropylene shell around three sides of the board. The capped layer is fully bonded to the substrate to prevent delamination. This process not only adds a seamless, integrated layer of protection against stains, spills and everyday foot traffic, the hard shell also contains UV inhibitors that help protect the decking from fading over time.

Although heavier than wood, composites offer many advantages, including resistance to rot, and the ability to never warp or splinter. Paint? Sealer? Stains? Nope. Never. 

The Difference Between Polyethylene and Polypropylene 

Using a blend of reclaimed hardwood fiber and rugged, UV-stabilized polypropylene plastic (PP), DuraLife® composite decking’s unique formula provides more stability and better performance than composites made with other types of plastic, such as polyethylene (PE) and PVC.

Polyethylene is the most commonly used plastic in the world. Over 70% of the polyethylene produced is used in the packaging industry. From plastic milk jugs to shampoo bottles, motor oil containers to cutting boards, high density polyethylene (HDPE) provides a strong, easily recyclable material. Incidentally, many plastic recycling bins are themselves made from recycled HDPE. 

Polypropylene (PP) is also used extensively in food packaging. However, it is much less brittle than HDPE, offering very good resistance to fatigue. Because of PPs superior resistance to chemicals and high melting point, it is also used to make plastic components used in the automobile industry.

Why Polypropylene Makes a Better Composite Decking

Both polyethylene and polypropylene plastics are commonly used in the manufacturing of composite decking products. Because of its greater availability (and lower recycling costs) polyethylene has long served as the most prevalent plastic used by composite makers.

However, over the past decade, consumers have started to demand better performance from their decking. As issues surrounding structural strength, sponginess, color fading, staining and high surface temperatures (aka hot-foot) began to surface, some composite manufactures began to look at other types of plastics.

With its higher melting point, polypropylene absorbs and retains much less heat than other types of plastics. What’s more, when blended with hardwood fiber, a composite deck board will remain significantly cooler than a board made entirely of plastic (PVC).

PP’s strength also delivers better performance when it comes to resisting flex or sagging between joists. This not only improves the overall aesthetics and structural integrity of the deck, it allows more flexibility in the creative design of the space as well.

See the difference for yourself. Order your Samples of DuraLife Composite Decking now and have them shipped directly to your door!

This article is made possible by DuraLife. DuraLife’s unique polypropylene and hardwood composite decking materials simply outperform all other wood and composite decking products. More solid and safe under foot, DuraLife decking is backed by a 25-year warranty. It is stain and fade resistant, mold and mildew resistant, and is available in the colors and deck railing options you want. Get Samples, try our Composite Deck & Railing Visualizer, or contact DuraLife now to learn more.