Timber: Large scale LVL at Netball Central, Homebush
28 May 2014
By Willow Aliento
28 May 2014 — The largest laminated veneer lumber portals ever used in Australia are currently being erected at Netball Central, at Sydney’s Homebush, but it’s taken architect Claire Matheson from Scott Carver to become somewhat of a pioneer to achieve a result that may now pave the way for more industrial-scale timber buildings.
In designing the project, Ms Matheson travelled to New Zealand to meet with fabricators and suppliers of specific LVL she wanted to use on the project, she learned about its characteristics and developed approaches to orientation that would minimise costs, such as sanding. In the absence of specifications for LVL finishes, she developed her own.
Importantly, the project, for the headquarters for the Netball New South Wales at Sydney’s Olympic Park, will also produce sustainable outcomes, Ms Matheson told The Fifth Estate.
“I am very interested in sustainability; it is a driver to a lot of my [design] decision making,” Ms Matheson said.
“LVL being timber, and a renewable material, is sustainable. It is a carbon sink, and the process of manufacturing it has a better feel for us [than some alternatives].”
LVL is also made from softwood, not hardwoods, so it is value-adding to the raw plantation-grown material.
“Another major reason [to use LVL] was this is the first elite sporting facility which is purely for a female sport, so we wanted it to have a unique feel – not the standard white and grey [concrete and steel]. Timber has a warmth [to it].”
Ms Matheson worked closely with the building’s structural engineering and sustainability consultants, Arup, to establish that LVL would work from an engineering point of view, and also that in terms of value engineering it would measure up to steel-based alternatives.
“Essentially it’s a big shed,” Ms Matheson said. “However, the scale with the LVL timber members for the portals is massive, and forms part of the architectural language of the building.”
“The structural techniques [within this building] are quite innovative. It is the largest use of LVL portals [using Quick Connect jointing] in the southern hemisphere, possibly the world. The portal rafters [which span the 25 metre length of the netball courts plus an overrun at each end] have a maximum 37m clear span, which approaches the maximum that could be achieved with the maximum manufactured width of 1200 millimetres.”
The portal rafters are joined at the apex with just four bolts in an innovative Quick Connect jointing, which was invented by a consortium of Australian and New Zealand manufacturers in collaboration with the University of Auckland.
Ms Matheson noted this made the portals quicker to construct on site, requiring far fewer bolts than the number of screws for traditional timber connections, with a corresponding reduction in the amount of work at heights required, thereby also improving safety.
While there is some LVL being produced by Hume in Australia, the LVL for the project was sourced from New Zealand.
Ms Matheson said the engineering expertise that will help enable a market for Australian-produced products to develop is, however, advancing rapidly.
“Arup is doing a lot with timber design,” Ms Matheson said.
“The use of mass timber is being engineering-driven. [For architects] it’s about understanding the product. I went to New Zealand and met with a number of fabricators and suppliers including Nelson Pine and Carter Holt Harvey, and saw how it was manufactured and how it can be used.”
Through an understanding of the manufacturing process, Ms Matheson became familiar with some of the other characteristics of mass timbers, including appropriate orientation to reduce the need for sanding, which in turn reduces production cost.
In terms of Australian standards, there is an issue in terms of lack of a national specification on how to specify LVL in terms of its aesthetics, in contrast to plywood or concrete, where there are grades and classes of finishes.
“I had to develop my own grading for the visual face of the LVL,” Ms Matheson said.
“To some extent we now have a vocabulary to use. Initially, manufacturers of LVL were thinking of it as an industrial material, so I had to communicate with the manufacturers about how to [produce the required finish], and develop a means of describing it.”
While LVL and other mass timbers have advantages in terms of reduced onsite labour and materials requirements compared to steel and concrete, as they are softwood, they are more vulnerable to impacts on site and during construction.
Ms Matheson said there needed to be a process of educating contractors and subcontractors on handling and storage, and that there is a certain degree of nervousness on the part of some contractors about the material’s vulnerabilities.
“Netball Central is a first of its kind structure in LVL. It has been a learning curve for all onboard, including the logistics of working with an unknown material.
“The fact it is a learning curve is the exciting story [about this project]. Only once there have been a few more projects being built [with mass timbers in Australia] will people be able to see the benefits and possibilities.”