Last week’s article, ‘Australia on 'cusp' of transformation in timber building’, looked at how the use of engineered timber in Australia is growing in popularity, and is being used in more intricate and interesting ways than ever before.
This second part of BPN’s feature on engineered timber delves deeper into some of the technologies enabling unprecedented timber building construction.
Technological advances
New developments in technology have played a major part in engineered wood products being used more often and in more interesting ways.
A pivotal piece of technology, which has been developed by research consortium Sustainable Buildings of the Future (STIC), is the EXPAN system. It makes building standard commercial building grids of nine by 12 metres an easy feat for timber, where previously it was not possible.
The EXPAN prefabricated construction system embeds post-tensioned tendons into timber to lock the system together. This allows new ventures in design and the ability to construct commercial and industrial buildings out of timber.
This technology was used in the Massey University College of Creative Arts building in New Zealand to allow the timber beams to flex during an earthquake, so as to withstand the ground shaking and acceleration.
Not only does the technology provide the strength to withstand a powerful earthquake, but the long-span exposed timber provides a warm aesthetic to the 3600 sqm gallery, studio and teaching space.
Architect Katherine Dean, from Athfield Architects in New Zealand, says “The timber technology gives us the big, open span frame for a completely uninterrupted space with no partitions that enables Massey to adapt the space over time to change with teaching needs.”
The EXPAN system has allowed engineered timber to have the strength and endurance of steel, yet the stylishness of timber. It provides a place for timber in commercial and industrial design.
Exciting time for timber industry
“It is an exciting time for the design and building sector and the Australian timber industry,” Wood Solutions’ David Simpson says. “Architects and engineers are beginning to see the creative possibilities and exploring the challenges of new timber systems, materials and applications.”
One architect who has already seen the possibilities is Paul Haar, architect of Candlebark School Library in the Macedon Ranges, Victoria.
Despite being told by the structural engineer on the project that the underground roof would need to be held up by concrete and/or steel structures, Haar remained adamant to use an all timber roof frame because of the carbon sequestered in it from the atmosphere, its easy workability and potential aesthetics.
He proposed massive post and beam portals that carpenters could fabricate off site in seasoned pine laminated veneer lumber.
Beginning with 12m long by 1.2m wide by 35mm and 45mm thick slabs of LVL, they were shaped and vertically screw laminated into 12m long by 600mm deep by 205mm thick roof beams that span continuously over posts.
No timber was wasted from the original LVL slabs, as cut-offs were ripped into 140mm deep purlins that span between the roof beams. Structural grade seasoned pine plywood was laid over the roof purlins to complete the roof.
It supports between 500-600mm of earth, effectively 2.5 tonnes per sqm, which shields the building against heat during summer and potential wildfire.
Environmental advantages
By using engineered timber, environmental advantages can be had – it is the only sustainable structural construction material of scale.
This is evident in Melbourne’s Forte building, of which a Life Cycle Analysis has been conducted by Melbourne’s RMIT University. It showed the building reduced cumulative non-renewable energy demand by 56 per cent and lowered eutrophication (the supply of excess nutrients to the water system) by 75 per cent.
“The figures show how significant the substitution of an engineered wood product can be in one relatively small building. Increasing their use across larger multi-residential and commercial projects could have a substantial impact on Australia’s carbon economy,” Simpson says.
Two more timber buildings are under construction in Melbourne – the Dockland Library and Community Centre, and Melbourne University’s Parkville Campus Architecture building.
“All in all, there are some 20 heavy engineered timber – mostly CLT – buildings in various stages of planning, design, documentation and construction in Australia,” he says.
Candlebark images: Kristian Laemmle-Ruff.
