The period from 2009 to 2018 saw an increase in the number of apartments being constructed in Australia as a result of population growth within cities, demand for more affordable dwellings, and greater employment opportunities in urban areas. The Australian construction sector is generally considered to be conservative and consistent with this the construction of apartments has been strongly traditional in the use of materials and methods.. It is anticipated that there is great potential for improvements in the productivity of the Australian construction industry from supply chain and construction method innovation.

Emma Heffernan works as part of a multi-disciplinary team at the University of Wollongong undertaking research to explore the central topic of cold-formed steel building systems for the mid-rise residential sector in Australia. Mid-rise apartment development is defined as between four and eight storeys.

Loadbearing cold-formed steel (CFS) is a construction framing material manufactured from cold-rolled and metallic coated steel coil. The coil is cut into thin strips and passed through a roll-forming machine, typically to form a ‘C’ section; no heat is required in this roll-forming process. CFS has a number of inherent benefits: steel contains both recycled content and is recyclable, cold formed-steel offers reduced waste during manufacture and construction, and its ductility is useful in deflection to absorb wind loads. Other benefits include its high strength-to-weight ratio, dimensional accuracy, dimensional stability, and simplicity of handling.

The approach

To explore the feasibility of using CFS for mid-rise residential construction in Australia, a seven-storey archetype building, containing 60 apartments, was designed by COX architects. The archetype building was originally designed to be constructed using concrete, and was subsequently redesigned for the use of loadbearing CFS. Using the two versions, the multi-disciplinary team was able to undertake a detailed comparison of the same building using alternative construction systems.

For the archetype comparison, a number of evaluation criteria were determined. The five categories: Economic, Social, Technical, Environmental, and Legislative. A few of the primary evaluation criteria included:

  • Construction cost
  • Project duration
  • Technical feasibility
  • Occupant thermal comfort
  • Energy
  • Life-cycle assessment, and
  • Regulatory compliance

Digital modelling was used in the comparison to support the analysis.

Potential impact

Emma’s team found that, in the case of their archetype, CFS offered reductions in cost of structure and overall construction cost. However, there were also other linked benefits to this; the number of trades and workers on site was reduced, and this reduced the complexity of construction on site when using CFS. CFS also offered a reduction in project duration which contributed to the overall savings in construction costs. The team concluded that steel is technically feasible for mid-rise residential buildings in Australia, and noted that optimal construction solutions for the Australian supply chain would need to be developed.

There is therefore a potentially significant impact on the Australian construction industry and residential market if this construction system becomes mainstream. Construction sites could become safer through the use of CFS, where fabrication is conducted off-site in a factory environment. With reduced construction costs and increased speed of construction, there is potential to make apartments more affordable, or to enable development on sites which would otherwise not be developable.

Personal highlights

Emma has found working on this research project rewarding for a number of reasons. By working within a multi-disciplinary team it has been possible to address the research holistically. This has also been made possible through the collaborative work with all of the industry partners. Other highlights for her have included the opportunity to learn more about cold-formed steel and to explore innovative construction solutions for apartment buildings.