The Green approach to building a deck that will last a lifetime

As in most parts of the building industry, the demand for green decking continues to surge. Savvy marketers are taking advantage, promoting the green qualities of their manmade or natural wood materials. But the greenest option might be the one consumers know the least about and comprises less than 5% of the decking market.

So just how green are tropical hardwoods?

Most people think of green products as having minimal long-term impact on the environment, from raw material sourcing to manufacturing, selling, and end-of-life disposal. The challenge for hardwood advocates is that most cradle-to-grave life cycle studies focus on other decking materials, specifically natural softwoods, treated softwoods, and wood-plastic composites. We can still learn from these studies, however, as hardwoods share many of the same life cycle traits as softwoods.

Let’s start with the studies’ basic findings: Solid wood products with natural resistance to insects, rot, and decay (such as redwood and cedar) and treated softwoods have a significantly lower environmental impact than composite or plastic decking products*. Given this information, we can infer a number of conclusions about hardwoods by focusing on four environmental factors: responsible sourcing, durability and lifespan, environmental impact, and end-of-life disposal.

Hardwood decking is made of tropical tree species, harvested from tropical forest areas around the world. Contrary to popular belief, however, logging is not the root cause of tropical deforestation. The conversion of tropical forestland to ranches and farmland is far more destructive, a trend that’s exacerbated by energy companies seeking to produce more agro-fuel crops. In fact, most countries in the tropics have initiated strict logging regulations that are growing in scope and enforcement.

When properly regulated, sustainable logging can actually slow or reverse deforestation by adding value to forestland and providing a viable alternative to farming and ranching. Plus, tropical countries are eligible for carbon sequestration projects, providing incentives to plant new forests, replace old ones, or grow plantation forests consisting of fast-growing decking-appropriate species. Replenishing depleted forests or planting new forests has the potential to provide income to developing countries, offset companies’ fossil fuel emissions, boost the supply of eco-friendly wood products, and increase tropical forest area (this has already started in some countries).

Solid wood has a long track record of performance. Softwood decks (not old growth) may last 10 to 15 years on average, depending on care.

By comparison, tropical hardwood decking can last two to three times as long as softwood decking. For example, the Coney Island boardwalk was renovated with ipé (the first proven hardwood decking species, along with Tigerwood and cumaru) in the 1960s and sections of the Atlantic City boardwalk in New Jersey were replaced with ipé in 1989. In both of these heavy commercial applications, the hardwood decking is still performing well.

All solid wood decking products require UV protection for color preservation, but as you move from treated to cedar/redwood to hardwoods, the required maintenance declines. Because hardwoods are much denser, they’re also far more resistant to scratching, denting, and other surface degradation.

Wood-plastic composites have a significantly higher impact than solid woods in every environmental measure, including embodied energy, global warming acidification, aquatic eutrophication, ozone depletion, smog formation, and human respiratory effects. Although the referenced studies focus only on North American softwoods, the practices used in tropical forestry are extremely similar up to the point of shipping from source to market.

Because decks made of tropical hardwoods can last up to three times longer than softwood decks (and equal to or more than composites), it’s reasonable to assume this longer lifespan offsets additional embodied energy used during transportation in overall environmental impact. Even if the wood composites last three times as long as softwood-no one really knows their life expectancy-the studies still believe that solid wood products will have a smaller environmental impact.

What happens when the product wears out? Natural solid wood products are recyclable and biodegradable, eventually reverting to soil over time. Hardwoods generally take longer to biodegrade than softwoods, but the slow degradation is offset by hardwoods’ longevity.

Wood-plastic composites are not recyclable and end up in a landfill. Some manufacturers claim to make plastic decking from 100% recycled materials, but the plastic can’t be recycled indefinitely; eventually it ends up in a landfill as well and will not biodegrade in any reasonable time frame.

Tropical hardwood decking offers a number of environmental advantages over other materials. It lasts longer, requires less energy from cradle to grave, is available through selective and sustainable logging practices, and is biodegradable. Those looking for a green decking option should consider tropical hardwoods as a viable option.