The case for wood
Sustainable, carbon sequestering, flexible, strong. Wood is the perfect building material.
New Zealanders don’t have to look far to see the immediate benefits of wood as a structural element in building. The images from Christchurch after the earthquakes detailed crumbling masonry, slabs of peeling brick veneer, the shocking sight of a city turned inside out.
Not all concrete-and-steel buildings fare badly in an earthquake — but the older, and badly designed ones without reinforced masonry in Canterbury did. A report on the performance of residential houses in the Darfield area, carried out in the aftermath of the September 4 earthquakes by Prof. Andy Buchanan and Michael Newcombe from the University of Canterbury’s Department of Civil and Natural Resources Engineering, discovered that the building stock — which is mostly light timber frame construction — performed well overall in comparison to other areas. Most damage was caused by the collapse of masonry chimney on older houses, and the settlement of foundations in areas of soil liquefaction. Timber construction company Lockwood also reports its support team had a hugely positive response from homeowners in the region after both earthquakes.
Perhaps it’s not surprising that something designed by nature, rather than man, is better able to withstand a natural event. The Japanese and Californians, like us, live on fault lines, and tend towards low-rise, wood-framed residential housing. Lighter and more flexible than concrete, and often more cost-effective and quicker to build with, sustainable wood is also the ultimate renewable resource.
While timber has always been part of the construction landscape in Aotearoa, from the marae to the white weatherboards of colonial homes, contemporary residential architecture is redefining the concept of wooden houses into something that is less rustic, more revolutionary.
The latest winners of the Home of the Year award, Herbst Architects, have built their career on airy, light-filled wooden homes that make their inhabitants feel close to nature without compromising the natural environment — the majority are on Great Barrier Island, and therefore off the electricity grid and largely self-sustaining. The award-winning Piha Bach — dubbed “Under Pohutukawa”, as it sits in a grove of the native trees — was, like the others, constructed using only sustainable woods; mostly cedar and poplar ply.
“We’re interested in the patina that develops through age, using cedar that fades to driftwood-grey colours, and letting nature do its thing, instead of plasticising everything,” says principal Nicola Herbst.
Erected in 1876, Wellington’s old Government Buildings are proof that wooden buildings can stand the test of time, and larger projects in New Zealand are now also pushing the limits of wood as a structural entity, both functionally and aesthetically — think Noel Lane Architect’s refurbishment of the grand atrium at Auckland Museum, the award-winning Waitomo Caves Visitor Centre or Irving Smith Jack Architect’s NMIT Arts & Media Building in Nelson, which was the result of a governmentsponsored national design competition to encourage the use of timber in multi-level buildings. After the 2008 earthquake in L’Aquila, Italy, which left 65,000 people homeless, residents of the small city made it clear to the authorities that they did not want to return to concrete buildings. The construction industry there began focusing on timber reconstruction — not only for single- or twostorey houses, but high-rise structures. In other parts of the world, they’ve gone beyond post-earthquake restoration and are designing new buildings completely in wood, using new technology and wood treatments.
Vancouver architect Michael Green, for example, is currently building a 30-storey “woodscraper” as part of the Tall Wood project, a new breed of large, zero-carbon buildings that use wood as a central component in Austria, Norway, and most recently Melbourne (the Delta Building). Green is using modern wood materials made of wood fibres, which are stronger than single pieces of wood and eliminate the need to cut down large trees. And, counter to popular belief, heavy timber components pose no greater fire threat than untreated steel.
From the marae to the white weatherboards of colonial homes, contemporary residential architecture is redefining the concept of wooden houses into something that is less
rustic, more revolutionary.