Why Look to Wood? Why Wouldn’t We? 1

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Wednesday, May 6th, 2015
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Throughout its history, the construction industry has been confronted with challenges.

As is so often the case when challenges are presented, our industry found its heroes. For centuries, stone, bricks and wood were ‘hero’ materials, and whether building a bridge or a barn, the craftsman would almost invariably turn to masonry, wood or a combination of the two to execute his architectural vision.

While timber was relatively abundant and easy to work with, wood struggled to deliver the strength and stability that ever-higher building designs demanded.

What’s more, the countless stories of city conflagrations – the Great Fire of London being the most famous – point to the historical dangers posed by traditional timber as an industrial-scale urban building material.

Enter reinforced concrete – the Industrial Age’s building material hero. Just as rapidly as the world’s city skylines rose, sand, gravel and steel quickly replaced timber and stone as the go-to construction material combination. Why? Because concrete allowed us to create big, strong buildings – and to do so in a fast and efficient manner.

At over 828 metres and 160 storeys, the Burj Khalifa in Dubai is perhaps the world’s most powerful monument to the rise of reinforced concrete in the construction industry. More than 45,000 cubic metres of concrete was used to construct the building’s foundation alone, while 39,000 tonnes of steel rebar was used to reinforce the concrete in the overall structure.

Throughout its construction, the Burj Khalifa achieved world record after world record – from the highest vertical concrete pumping operation from the ground (601 metres), to the tallest service elevator shaft and the highest occupied floor.

But while reinforced concrete has enabled the construction industry to reach new heights, our favourite hero material does have its downside. Like stone, bricks and timber before it, reinforced concrete’s rise has been guaranteed largely by the perceived abundance of its core elements. But our supply is not as endless as it seems.

The United Nations Environment Programme (UNEP) reports that sand and gravel account for the largest volume of solid material extracted globally, with an estimated 47 billion to 59 billion tonnes mined every year. UNEP says the world’s use of aggregates for concrete in 2012 was enough to build a wall 27 metres high by 27 metres wide around the equator. These figures don’t even include all the sand and aggregate used for land reclamation and the creation of other sand-based products like glass, computer components and other consumer goods.  In fact, according to UNEP, we are now at a point where our use of sand far outstrips the rate of its renewal.

So again we must seek hero materials that are strong, fast and abundant. Smart companies both here and overseas are already writing a new hero story – but the twist is that the lead character is not new. Instead, it’s an old favourite reimagined.

Enter engineered wood products. Lightweight, strong, durable and easy to assemble, engineered timber building materials such as cross laminated timber (CLT) and laminated veneer lumber (LVL) are making waves and breaking records across the globe.

Manufactured from fast-growing tree species – and thus not inhibited by the need for large pieces of solid timber that take years to grow to size – engineered wood products take relatively small pieces of wood and glue, press and seal them together to create a material with comparable tensile strength to reinforced concrete.

By using engineered wood products, leading construction companies are now creating buildings that are just as strong, but around 30 per cent lighter than their concrete and steel counterparts. Lighter buildings mean less material required for foundational stability – a win for engineered wood, resource conservation and the bottom line.

But the benefits don’t stop there. In operation, buildings created with CLT require significantly less energy to heat and cool – not to mention the carbon sequestering power of the wood itself.  In fact, approximately 50 per cent of its dry weight is carbon.

Engineered timber materials also lend themselves to more localised production and modular building techniques. These products can be grown, manufactured and cut to size close to site, making for quicker and more cost-effective construction with reduced impacts on freight and infrastructure. Using timber can be about productivity as much as it’s about sustainability.

If the Burj Khalifa is the world’s monument to concrete and steel, then Lend Lease’s landmark Forté building in Melbourne may be the structural testament to our industry’s next material hero. The 10-storey residential apartment was constructed using CLT panels and currently holds the record as the world’s tallest modern timber apartment building.

When you consider that CLT can weigh up to 80 per cent less than traditional concrete, the mere 500 tonnes of CLT panelling used to construct Forté represent incredible energy and cost savings. In fact, by minimising the use of concrete and steel in favour of CLT, Forté has eliminated 1,450 tonnes of carbon dioxide from the atmosphere – the equivalent of removing 345 cars from Melbourne’s roads each year.

Pre-cast engineered timber products represent a new way of thinking about the building process and open the construction industry to new possibilities when it comes to sustainability, strength and speed of completion. The legend of a new (old) building material hero – engineered timber – is growing just as rapidly and sustainably as its raw materials.

In words of Professor Alex de Rijke, founder of London’s dRMM Architects, “If the nineteenth century was the century of steel and the twentieth century of concrete, then the twenty-first century is about engineered timber.”

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  1. Harold Lee

    About time the construction sector reconsiders timber for taller buildings – The latest technological advances have made wood a sustainable and cost-effective buildingsolution.