Composite Decking: Is it Really Sustainable?

Composite decking has exploded in popularity in recent years, touted as a low-maintenance and eco-friendly alternative to traditional wood. But before you rush out and replace your deck, it's important to take a deeper look at the environmental impact of this material.

A Recycled Facade?

The allure of composite decking lies in its recycled content. Manufacturers often highlight the use of byproducts like polypropylene and polyethylene, remnants from oil production. While this does technically qualify as recycled material, it's important to remember oil itself is a notoriously environmentally damaging resource to extract and refine.

Sustainability or Shifting Waste?

So, composite decking uses recycled plastic, but is it truly sustainable? Consider this: while some tree species used in traditional wood decks are harvested, they are often replanted at significant ratios (10:1 or 20:1). This means responsible logging companies contribute little to deforestation. In contrast, the oil industry doesn't replenish a finite resource, simply managing some of its waste through composite materials.

The End of the Line: Landfills and Beyond

The problems with composite decking go beyond its origins. These supposedly "green" products end up in landfills because they are not biodegradable. Unlike wood, which decomposes naturally even in the ocean, composite decking can persist for hundreds or even thousands of years.

Fire Safety and Toxic Concerns

While some wood decks require careful fire management, composite decking introduces a different set of concerns. When burned, it releases toxic fumes due to its plastic content. This makes it a risky choice for areas with grills or fire pits. Even a minor fire can melt and warp composite boards, leading to replacements that ultimately end up in landfills.

The "Monstrous Hybrid" Problem

The very aspect that makes composite decking appealing – its mix of plastic and wood – creates a sustainability nightmare. This "monstrous hybrid" (as termed by sustainability experts William McDonough and Michael Braungart) cannot be recycled or composted. Sawdust and construction scraps become unusable landfill fillers.

Beyond the Environmental Impact

As a designer, I've heard numerous complaints about composite decking beyond its environmental shortcomings. Customers often cite issues with bowing, difficulty cleaning, and staining from pollen. Many who have opted for composite decking regret their decision.

The Challenge of Recycling Composite Decking

Even the recycled plastic content of composite decking presents unique challenges. Mechanical recycling, the most common method, often involves labor-intensive sorting and can expose workers to hazardous chemicals if proper protection isn't used. Emissions from poorly run facilities can also pollute the environment.

One specific challenge is Polyvinyl Chloride (PVC), a common component in composite decking. Recycling PVC is complex because:

• Mixed plastic streams can render PVC unusable if the PVC content is too high.

• PVC requires meticulous separation from other plastics due to its additives, which can contaminate the recycling stream.

• Even recycled PVC may contain hazardous additives that can end up in new products.

The Takeaway: True Sustainability Lies Elsewhere

Composite decking may appear eco-friendly on the surface, but a closer look reveals a different story. From its reliance on environmentally damaging oil production to its non-biodegradable nature and problematic disposal, composite decking raises significant sustainability concerns.

Let's be clear: recycling plastics is a positive effort, and we acknowledge it's a complex issue without a perfect solution. However, the challenges associated with composite decking extend beyond environmental impact. There's a dishonesty in materiality at play. For any designer who values good craftsmanship, this can be a significant turnoff.

While composite decking may seem like a lesser evil compared to some alternatives, we believe the best course of action is to prioritize local, renewable resources with a more circular lifespan. Responsibly sourced wood species grown with replanting programs offer a beautiful, environmentally responsible choice for your outdoor space.

By understanding the complexities of composite decking, we can make more informed decisions and encourage the development of truly sustainable building materials for the future.

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