High rise wooden towers touted

Connal Townsend, chief executive of the Property Council. Photo / Supplied

Plyscrapers - high-rise wooden office towers - could become more popular after the Christchurch earthquake.

Connal Townsend, Property Council chief executive, has returned from the Green Cities conference in Melbourne where he said an address was given on the prospect of wooden structures becoming more prevalent, partly in a drive to offset carbon dioxide emissions from concrete.

Wooden structures have also been cited as standing up better during an earthquake.

Most new houses are built on concrete floor pads. High-rise towers have extensive pre-cast concrete panels as floor and wall components.

Townsend heard the keynote address by Michael Green, a partner in the Vancouver firm McFarlane Green Biggar Architectures + Design, who told of his vision of the world's first timber skyscraper.

Green said a study funded by the British Columbia government to help promote the forestry sector found buildings as tall as 30 levels could be made almost entirely from wood.

"The exciting thing is, from an engineering point of view, we think we have something that is on track to be able to design - comfortably - 20-storey buildings," Green was quoted as saying by the Vancouver Sun. "We believe, quite reasonably, we'll be able to stretch that to 30 storeys."

The newspaper said that a nine-storey building in Britain is currently the world's tallest wooden structure. Green said a 10-storey project in Australia, a 17-storey building in Norway and a 30-storey structure in Austria have been proposed.

Townsend, of Auckland, said the concept of a wooden high-rise was entirely plausible and there was an international movement towards tall wooden buildings.

"The buildings are made of steel and wood but the spinal column is still steel. The objective is to minimise the use of concrete and emissions. Certainly, there's a drive on in British Columbia to do that. But I'd also make the point that in the Christchurch earthquake, modern steel, concrete and glass buildings escaped relatively unscathed so modern and contemporary construction techniques are good in an earthquake," Townsend said.

Warwick Quinn, chief executive of Registered Master Builders, was sceptical.

"New building technologies and techniques are developed all the time and techniques developed overseas may not be completely transferable without modification - or possible - given our environment, particularly for earthquake and wind.

"Nevertheless as these technologies are developed it is entirely feasible that something like a timber office tower may be an option for New Zealand but would need to be considered in the wider property context taking into account maintenance, services, rents [and] returns," Quinn said.

Chris Hunter, Hawkins Construction chief executive, said plyscrapers were feasible but maybe not to the height Green cited.

"You can certainly build high-rise timber building of 10 to 14 levels but I haven't heard of anyone building 30 levels," Hunter said.

New Zealand's eco-building conference is being held this month in Auckland on March 24 at the Pullman Hotel.