A high-rise built out of timber, not steel? It’s a solid idea according to Queensland University of Technology (QUT) structural engineering researcher, Dr Craig Cowled, who has embarked on a three-year project to identify the best way to build carbon-storing, timber-framed ‘plyscrapers’.
Tall buildings made out of timber, rather than concrete or steel, are considered to be cheaper and faster to construct – while using a sustainable resource that locks away carbon for the life of the development.
Dr Cowled is on a mission to boost this fledgling segment of the construction industry. The researcher has been awarded a $240,000 Advance Queensland Aboriginal and Torres Strait Islander Research Fellowship to research and develop a new building system and guidelines for timber buildings up to eight storeys.
Now with the Queensland Government aiming to reduce the state’s carbon emissions by 30 per cent by 2030, Dr Cowled believes an increase in timber multi-storeys will be a big win for the environment.
“My research with this fellowship aims to develop a new building system and guidelines that eliminate some of the current technical obstacles to timber frame construction for taller buildings,” he said.
“By increasing the market share of timber, which stores carbon, Queensland can make significant reductions in the CO2 emissions of the construction industry.”
The National Construction Code (NCC) 2016 increased the allowed height of timber buildings from three storeys to eight storeys (25 metres). From 1 May, changes to the 2019 NCC Volume One will increase the range of buildings, in which fire-protected timber construction systems can be used. The new Classes add schools, retail premises, hospitals and aged care facilities to the previously approved multi-residential, hospitality accommodation and office buildings.
Despite this, Dr Cowled said Australia’s current building standards for timber buildings have been designed with the old height limit of three storeys in mind.
“I’m aiming to produce two tangible outcomes – a new light-weight, panelised timber-framed building system to withstand the higher loads of taller buildings, and a technical design guide for the building industry to make it easier to adopt this method of construction.”
His research will focus on buildings up to eight storeys, with the findings also expected to benefit higher buildings.
Dr Cowled is seeing the material increasingly gain in popularity with developers across the country and the world because it is quicker and cheaper to build with than concrete and has great environmental credentials.
“Timber is a sustainable resource and, just as a tree stores carbon, a timber building will store carbon and lock it away during the building’s lifetime,” he said.
“Every tonne of plantation timber has a tonne of carbon sequested in it. But concrete has the reverse effect on the environment as carbon dioxide is burned off into the atmosphere during cement production.”
Dr Cowled said advances in manufacturing techniques, such as cross-laminated timber, and improvements in fire engineering has opened the door for taller, ‘greener’ buildings.
“But as the height increases, the amount of the building exposed to wind increases and that wind load needs to be transferred right down to the foundations,” he said.
“I’m aiming to increase the strength of timber panel framing systems, including the ‘shear walls’ which need to have enough stiffness to transfer the load down to the foundations. This is one of the elements that stop taller buildings from swaying in cyclones or earthquakes.”
Dr Cowled’s research will include “some good old fashioned engineering tests – building walls and seeing how much it takes to knock them down”.
The testing will take place at QUT’s Banyo Pilot Plant over winter, with the Engineered Wood Products Association Australasia also on board as an industry partner to supply materials and guidance.