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Composite Decking

Stylish Yet Long Lasting Decks


Composite Decking
HRae/Wikimedia Commons/CC by 3.0

We love our decks, our porch swings, our beers and mint juleps as the sun goes down. What we hate about our decking is the maintenance. However diligent we are, real wood always needs to be repaired, retreated and replaced. If you are lucky enough to have real teak decking then maintenance is not such a chore, though teak still has drawbacks such as slivers, in common with other woods – and  even teak needs attention to keep it mold-free and moss-clear.

Nowadays, there is an alternative to wood. It is called composite decking. The planking is made from a range of materials, even including wood.

Materials Used

Most composite decking is manufactured from wood by-products (sawdust, wood chips, recycled lumber) and recycled plastics. Synthetic and organic materials in tandem offer a durable product with the look and feel of real wood (except the slivers). Some manufacturers use hemp as an alternative to wood cellulose.

Cost is always a factor, and the more expensive (and arguably higher quality) composite decking does not use recycled material. Hardwood flour is sourced directly from lumber mills and other suppliers, originating from new cut wood. The polyethylene used as the binder is not drawn from recycled stock (which can contain impurities), but is original manufacture. In fact, a range of polymers is used, with both high- and low- density polyethylene, PVC and polypropylene in the various ‘recipes’. Typically, the cellulose content (wood flour) varies in proportion between 40% and 60%,

UV protection can be provided by dosing the polymer compound with a chemical, but not all products have it as standard. Some manufacturers offer insecticide additives – after all, there is wood in the mix, potentially open to attack.

How the Decking is Made

A few manufacturers use compression molding which delivers a physical wood pattern raised grain finish, giving an extra degree of realism (and anti-slip properties in the wet).

Co-extruded decking is also made. Hollow vinyl deck boards (which give a hollow sound when walked on) are being supplanted by cellular PVC made with the co-extrusion process. The cap layer and the core or foam layer are extruded from the machine at the same time, so that a second bonding process is not required.

Alternative Finishes

A range of grains and colors are offered so that a range of design effects can be achieved from wood lookalikes, both softwood and hardwood. Raised grain finishes are also available.

Top range products may even offer random grain finishes, claiming that no two boards will have the same grain. Of course, not even real wood cut from the same tree is like that, but it does offer a degree of variety and make a deck less obviously synthetic.

Advantages of Composite Decking

  • Stain, split, scratch resistant
  • Mold and mildew resistant
  • Durable, long lasting and does not warp
  • Impervious to moisture and insects
  • Most formulations are 100% recyclable
  • Higher cost (50%-100% more than cedar)
  • Color is fixed and a makeover is impossible (other than cleaning)
  • Darker colors may fade, and high-traffic areas may be difficult to re-color when worn

The Disadvantages

Most manufacturers advocate cost saving by using an existing wood substructure, but all you do then is hide future problems. If you are spending money on composite decking, then consider going all the way and installing a composite framework too, though this solution is still relatively new.

The warranties offered by manufacturers vary widely, from 5 years to 20 years. ‘Limited warranty’ is a common term in use.

Finally, do check that the formulation you have chosen includes UV protection, to prolong your investment.

The Future of Composite Decking

Product formulations are still improving, and patents have been filed for a multi-layer decking that reflects infra red, so that darker color decks do not heat up uncomfortably in strong sunlight.

As production volumes increase and costs fall (depending on plastic feedstock market prices), then the considerable advantages of composite decking are certain to lead to increased replacement of the real wood alternative

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