Timber Construction: Locking Up Carbon in Buildings and Furniture

Timber Construction: Locking Up Carbon in Buildings and Furniture

Uncovering the Hidden Magic of Timber

I’m standing on a construction site in east London, surrounded by the familiar sights and sounds of a building project. But as I walk around, something quite extraordinary slowly reveals itself. This is no ordinary construction site – it’s a temple to timber, an oasis of calm amidst the chaos of the city.

The seven-storey building taking shape before my eyes is made almost entirely of wood. “The entire structure above the first floor slab is comprised of cross-laminated timber (CLT) panels,” enthuses Andrew Waugh, the architect leading the project. “All the walls, floor slabs, and even the lift cores are formed from timber, like a giant honeycomb block.”

Compared to a traditional concrete and steel building, this timber marvel weighs a mere 20% as much. “That means we need minimal foundations – we don’t need massive amounts of concrete in the ground,” Waugh explains. “It’s a game-changer for architecture.”

The Environmental Superpowers of Timber

But the real magic of this timber building lies not in its structural prowess, but in its environmental benefits. You see, wood from managed forestry actually stores carbon, as opposed to emitting it. As trees grow, they absorb carbon dioxide from the atmosphere and transform it into solid carbon, which is then locked away in the wood.

“A cubic metre of wood contains around a tonne of CO2 – more or less depending on the species of tree,” Waugh tells me. “That’s similar to 350 litres of gasoline.” Not only does wood remove more CO2 from the atmosphere than it adds through manufacture, but by replacing carbon-intensive materials like concrete or steel, it doubles its contribution to lowering emissions.

The Rise of Cross-Laminated Timber (CLT)

The key to unlocking timber’s environmental superpowers lies in a revolutionary building material called cross-laminated timber (CLT). Invented in Austria in the 1990s, CLT is made by gluing together layers of wood planks, with each layer perpendicular to the one below.

“The ingenuity is that the planks are made stronger by gluing them in layers of three with each layer perpendicular to the other,” Waugh explains. “This means that the CLT doesn’t bow or bend – it has integral strength in two directions.”

Unlike traditional wood products like plywood or MDF, which can contain up to 10% adhesive glue, CLT uses less than 1% bio-based polyurethane. “To look at, smell, and touch, it’s as pure wood as a child’s tree house – knots and all,” Waugh says.

Timber’s Global Takeover

The environmental benefits of CLT have not gone unnoticed around the world. Less than five years after its arrival on US shores, there are now CLT projects underway in almost every mainland US state. The US is investing in domestic CLT manufacturing, with factories popping up in states like Montana, Oregon, and Maine.

“The Americans planted lots of trees in Japan as part of the Marshall Plan – that was over 60 years ago, and they’re reaching maturity now,” Waugh tells me. “Counterintuitively, CLT also performs well in earthquakes, which makes it particularly attractive in Japan.”

But it’s not just the US and Japan that are embracing timber construction. Waugh’s order sheet from Ledinek Engineering, an Austrian-Slovenian firm that makes the presses for CLT factories, shows a sudden surge of orders from countries like France, Australia, Latvia, and Canada in recent years.

Year Countries
2013 Austria, Scandinavia
2017 onwards Japan, France, Australia, Latvia, Canada

Timber’s Versatility and Resilience

But what makes timber such an attractive building material beyond its environmental credentials? For one, it’s incredibly versatile. Structures made from CLT are much quicker to construct than concrete buildings, reducing labor costs, transport fuel, and on-site energy use.

“A recent 16,000-square-metre CLT building I worked on would have needed around 1,000 cement truck deliveries for the frame alone,” Waugh tells me. “To deliver all the CLT we needed, it was just 92 deliveries.”

Timber also has some surprising resilience properties. Contrary to popular belief, CLT performs exceptionally well in fires. “It’s designed to withstand heats of up to 270°C before it begins to char,” Waugh explains. “The charring on the outside then acts as a protective layer for the structural density of the wood behind it.”

In fact, a joint Italian-Japanese research team recently built a seven-storey CLT building and tested it on a shake table – a video of which Waugh describes as “cool but eerie.” They found that the timber structure could withstand shaking at the level of the 1995 Kobe earthquake in Japan, which destroyed more than 50,000 buildings.

The Challenges and Opportunities Ahead

Of course, timber construction is not without its challenges. There are valid concerns around the end-of-life disposal of timber materials, as well as the potential for forests to become net emitters of carbon if not managed properly.

“Unless we attend to the disposal of timber materials at their end of life, there is no guarantee that the overall cycle is making a positive benefit to society,” cautions Doug King, a chartered engineer and building sustainability advisor.

But Waugh remains undaunted. “The average lifetime of a building is 50-60 years – that’s more than enough time for architects and engineers to work out the re-use and recycling issues,” he says. “Turning it into biochar could be one possibility.”

Ultimately, Waugh is convinced that mass adoption of CLT is an essential weapon in the fight against climate change. “It’s not a fad or a fashion,” he tells me as we finish the tour. “Everybody should be building with this. It has to happen – it’s imperative.”

As I take my final breath of that forest-fresh air and head back into the city, I can’t help but agree. Timber construction is the future, and the future is now. I’m excited to see what the team at https://timber-building.com will do next to lead the charge.


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