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Composite Decking Guide

The history of composite decking

Though wood composite decking may seem like a relatively new phenomenon – gracing popular home refurb Instagram accounts, property TV shows and glossy magazines – its roots date back further than you may assume. In fact, the invention of wood plastic composite can be attributed to Dino and Marco Terragni, two brothers who founded Covema in Milan and patented the product in 1960. This paved the way for the development of WPC and Icma San Giorgio – still manufacturing from the heart of Milan – patented the process of adding wood fibre to thermoplastics.

Fast forward to 1995 and a buy-out of a division of the American oil company Mobil Corporation gave raise to Trex – the powerhouse U.S composite company based in Virginia that now leads the industry in market share with over half a billion dollars in annual sales. In its infancy, the firm filed a US patent for the exclusive production rights to the method of “producing a wood-thermoplastic composite material”, later firming up their introduction onto the global marketing with the launch of the Trex decking product in 2009.

So what exactly is wood-plastic composite and how does it form the composite decking that we have become so accustomed to today? Well, WPC’s are ultimately created by mixing groundwood particles with heated thermoplastic resin which is then moulded into the correct shape and size – most regularly into decking boards. The process can be tailored further with the addition of colourants, UV stabilisers, foaming agents and lubricants to prepare the boards for domestic use and offer customers customised products around shape and colour. Processed at lower temperatures than traditional plastics owing to the addition of organic material, WPC’s usually begin to burn at around 400F and are used in a variety of recognisable items aside from composite decking such as phone covers or car door panels for example.

The burning temperate – or at least the temperature in which composites begin to change form – is important because it helps to explain the development of the product and how composite wood plastics have evolved into a global multi billion-pound industry. The rise in popularity of composite decking at the turn of the century led to firms ramping up operations to meet customer demand though it also presented an altogether new set of problems with discerning clients requiring differing varieties of composite, particularly around densities and compositions to best fit within specific geographical climates.

For example, in colder climates such as the winters of North America or Eastern Europe, the dense composite decking material would reach such cold temperatures that the cap-style screws would quite literally spin out of the boards. Coupled with the fact that the new plastic products came at relatively sky-high prices and that sturdiness was promised for decades, it gave both deck builders a technical headache and sent manufacturers into a marketing panic. Previously assumed set-in-stone spacing guidelines had been reviewed and revised to ensure that projects using composite materials – often with multi-million budgets – were stable, safe and capable of satisfying clients that were sold the array of benefits of the new project.

Later, the industry would arrive at the conclusion that changing the makeup and material of the screws would ultimately meet the needs of the builders who were working in varying temperatures and conditions. Fast forward to the present day and the market is awash with bespoke screws for all manner of environments.

The next evolution of composite decking was the process of forming an even stronger out layer on the surface of the boards – something previously unavailable to customers of the early variations. The process – known as co-extrusion – created what would become widely known as “capped” composite decking, making the boards stronger, more resilient and ultimately providing a more protective outer layer that would resist mildew and mould but crucially would better protect against scratches and marks – something that consumers would come to value hugely, particularly those with garden furniture who had relatively high footfall across their decks – think entertaining, barbeques and summer parties.

As the product was marketed to consumers, the benefits were an easy sell – particularly the fact that wood plastic composites do not corrode and are hugely resistant to the issues often arising with timber alternatives, most notably rot, decay and marine borer attack. Though the mechanical performance in wet and damp conditions is far greater than standard wood, the material can be enhanced further with acetylation treatment – something favoured by builders working on structures for large footfall projects, public places in city centres etc.

As wood composite decking, in particular, hit the market, manufacturers also became aware of another major selling point – the lack of need for paint. Wood composites are produced in a variety of colours for consumers wanting something a little different, though are also widely available in wood tones for those wanting to recreate timber with the added benefits of composite.

Some fifty years on from its invention in Milan, the future remains hugely bright for wood composites. The ability of wood composites to be tailored to specific uses, together with their strength properties and affordability, makes them an unavoidable solution to reducing the need for solid wood and timbers. They have been successfully applied in all forms of building, from small home projects to industrial construction work, and as the technology surrounding their manufacture only advances, fitters and suppliers are feeling more comfortable extending warranties on decks. With the obvious structural benefits, wood composite products are unparalleled as an environmentally sustainable product and with that in mind, the future certainly looks rosy. The consensus is that there’s never been a better time to buy.