Timber construction benefits are worth the effort
June 3, 2019
By Ralph Belperio, Major Projects Director & Timber Expertise Leader, Aurecon
One of the benefits of timber construction is that it lends itself to a large amount of prefabrication and offsite manufacture. This requires significant upfront design work much earlier in a project, but the effort is rewarded by advantages for on-site practices.
Timber high-rise building construction using off-site prefabrication typically requires a dramatically reduced workforce, is simpler, requires less scaffolding and eliminates the need for back-propping.
Crane movements are reduced due to the large size of the components and their reduced weight. Truck movements on-site are also significantly reduced, which is a blessing on a brownfield site in the CBD, for instance.
Overall, cost, noise, waste and time can be reduced and, most importantly, safety is improved through the use of engineered timber design and construction.
Amazing things can and are being done in Australia with timber in construction.
For instance, nine out of 11 stories at our 25 King Street, Brisbane premises were constructed using timber, making it Australia’s tallest engineered timber office building and delivers positive social, commercial and environmental impacts.
Inspired by the environmental benefits and versatility of timber, 25 King Street showcases timber from roof to floor.
The nine-storey plus ground superstructure utilises a combination of revolutionary engineered Cross-Laminated Timber (CLT) and glue laminated timber (glulam). The glulam is used for the structural beams and columns, and the CLT for floors, lift shafts and escape stairs.
This engineered timber has a lower carbon footprint than traditional building materials and is sourced from certified sustainably managed forests. It also allows for precise offsite prefabrication and safer onsite construction.
Aurecon has collaborated with Lendlease’s DesignMake, an advanced design and manufacturing business for timber solutions, for the structural design of 25 King Street.
As part of this process, DesignMake drew on its experience in the development of other engineered timber buildings, such as International House Sydney at Barangaroo.
Lower rise construction up to three or four stories may be more readily constructed from traditional timber framing, i.e. systems of joists, studs and rafters.
Engineered timber becomes the material of choice where larger spans or improved fire performance are required, particularly where the timber is to be exposed. Unprotected traditional framing is not a good solution where fire ratings are required, unless the timber can be clad in fire-resistant material, such as suitable plasterboard.
Constructing a timber commercial building requires rethinking standard project delivery practices and considering timber’s inherent structural limits.
Early documentation is necessary to enable prefabrication, requiring a very different approach to resolving the design, coordinating procurement and services, and finalising details ahead of construction, as it is difficult to make on-site adjustments.
In terms of material limitations, the shorter structural spans and increased number of columns reduce the wide spans traditionally expected in commercial floorplates.
Another consideration is the supply chain.
Buildings that contemplate greater prefabrication require additional pre-planning, design and material delivery strategies in order to realise the greater accuracy and time savings on-site that Design for Manufacture and Assembly (DfMA) can deliver.
There are many other considerations, such as design for durability, termites, fire, noise and vibration transfer. Each of these are readily solvable if you work alongside experienced practitioners who can guide you towards making good design decisions.
Ralph Belperio will present in the opening session "Building the future" at Timber Offsite Construction at Crown Promenade Melbourne on June 17.