2014 Australian Timber Awards – Judges’ Innovation Winner
CONGRATULATIONS TO AUSTRALAND
Winner of the Judges’ Innovation award in the 2014 Australian Timber awards, The Green is currently the tallest lightweight timber frame building in Australia. Constructed by the Australand Property Group, The Green adopted a new construction methodology using cassette panels built with Tecbeam joists, that achieved an efficient structure while utilising traditional timber industry framing techniques.
Overview of Structural System
The structure consists of a concrete car park below podium level with all five levels above constructed completely in timber. The superstructure was erected using prefabricated timber walls, floors and roof trusses that were manufactured off-site and delivered for installation. A collaboration between concept architects, SJB Architects and Australand created an efficient grid system and load transfer through the stacking of apartments.
Cassette Floor System
The prefabricated floor system, designed by Irwinconsult and Australand together with Tecbuild and its Australian licensee Tilling Timber, is a unique hybrid designed to address acoustic, fire proofing, fabrication, transport and lifting challenges. The floor cassettes are built with Tecbeam floor joists, constructed into panels, with engineered Promat floor sheeting. These floor cassettes were shop drawn by Tilling Timber for manufacture and for services integration.
Approximately 400m3 of concrete was used for the lower basement and ground levels, while only 500m3 of timber used for the remaining five levels of the superstructure. This resulted in significantly lower loads on the footings and foundation system when compared to a full concrete structure. As the majority of The Green was constructed using light weight timber, such reduction in building weight added further advantage as the building was governed by less onerous wind pressures. This hybrid construction methodology incorporated the traditional timber framing domestic labour force and supply chains to construct a multilevel residential timber frame building at a commercial standard. With the utilisation of the domestic labour force and building materials, a cost saving of up to 25% of build costs per apartment over conventional concrete was achieved.
Major program advantages over conventional building techniques became evident during the construction of the first level. Each floor level (averaging 850m2) was completed in about 11 days. This included all the internal walls being installed as part of each level’s construction cycle and no back propping was required as the unique properties of Tecbeam joists allow floors to span from load-bearing wall to load-bearing wall – some spans being up to 8.4 metres. The actual timber construction time (including roof trusses and floor cassettes) was only 12 weeks out of the 12 month build program.