Embracing mass timber construction in Australia – Graham Burrows

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As a founding partner and director of Jackson Clements Burrows Architects (JCB), Graham has overseen the design and delivery of numerous projects in the multi-residential, commercial, education, hospitality, and public sectors, including the practice’s mass timber work. He operates from the sincere belief that architecture can improve peoples’ lives and by extension, make cities more liveable and vibrant. 

He is highly experienced in leading complex major projects, design curation, planning approval processes, and multi-stakeholder consultation and has acted as an expert witness in VCAT hearings and given presentations to VCAT in relation to good design, context, and design response strategies.

 

In recent years, the property industry has witnessed a swift rise in the use of mass timber construction. Its extraordinarily renewable and sustainable properties and significant carbon savings when compared to concrete or steel make it an excellent option for building.

The residential and commercial building sectors in Australia produce 23% of our national greenhouse emissions. Our industry is responsible for indirect emissions resulting from material production, energy consumption and waste disposal.[i] As architects and designers, we’re passionate advocates for sustainable innovation. Using various combinations of mass timber and prefabrication, to date JCB has completed two major student living developments, with a further two projects in the works: Clifton Hill Primary School, under construction (also Passivhaus), and a 16-storey commercial tower set to be one of Victoria’s tallest mass timber buildings.

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WoodSolutions, which provides independent mass timber information and advisory to the industry, explains that Cross Laminated Timber (CLT) is the: “engineered wood of the future and is making the construction of entire buildings from timber a reality. First developed in Switzerland in the 1970s, CLT is an extension of the technology that began with plywood and may be best described as a 'jumbo plywood'.”[ii] So, even though timber as a construction material isn’t new by any means, innovation lies in the way that it’s now being manufactured and used by the industry today.

Project inception is the ideal time to explore if mass timber will be suitable as a construction material. Taking a holistic view of the project, start by considering the following benefits and challenges to determine if it will be an appropriate material for the project.

Benefits

  •  Lightweight and can reduce cost of foundations (or can enable the consolidation of existing structures through vertical extensions)

  • Competitive advantage through product differentiation

  • Low carbon, renewable and sustainable material

  • Adds warmth internally – natural and inviting material that supports wellbeing[iii] and biophilic design principles if timber can be exposed in the interiors

  • Safer and faster construction sequencing

  • Airtight, offering benefits for Passivhaus Certification

Additionally, there’s evidence that developers and building owners can expect that rents in low carbon and energy-efficient buildings will increase in response to higher tenant demand.[iv] This demand will be driven by the willingness of tenants to pay higher rents for buildings that align with their own environmentally sustainable ethos and aspirations.

Challenges

  • It may not be appropriate for all building types or locations, although it can be part of a hybrid structure

  • Fire engineering/fire rating approvals to work through (unless ‘Deemed to Satisfy’ detailing is used, for buildings up to 8-9 levels)

  • Potential for a small increase in upfront costs, as it normally involves more off-site manufacturing

  • Our growing local manufacturing industry is still not covering all the demand and projects may require overseas procurement

Designed by JCB, both Monash University’s Gillies Hall and La Trobe University Student Accommodation predominantly utilised CLT panels. Our experience shows that mass timber is particularly suited to modular building typologies such as apartments, student accommodation, teaching & learning and the commercial sector. The repetition of floorplate planning and the function of the building are good indicators of whether mass timber will be appropriate.

Case study 1: La Trobe University Student Accommodation

Completed last year, this $100M 624-bed student living development is the largest mass timber project in Victoria by volume, utilising 4500 cubic metres of Cross Laminated and GluLam timber. It also forms part of La Trobe’s ambitious plan to transform its Bundoora campus into a University City of the Future.

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Two schemes were initially produced: a traditional concrete scheme and a timber scheme. Both options were evaluated on their ability to deliver triple bottom line benefits to La Trobe University and its students. Ultimately, timber was selected as it offered the best overall performance to meet the tight timeline and the University’s sustainability goals.

Timber is particularly well suited to this type of development; the cellular arrangement of bedrooms results in regular and efficient structural spans and the height of the building (six-storeys) is well positioned for efficient CLT slab and wall construction. The lightweight nature of timber construction allowed significant savings in foundations as compared to the concrete reference scheme.

Over 75% of the approximate 20,000 sqm gross floor and roof area, and over 90% of the load-bearing walls and columns are constructed in CLT and Glulam. Enough CLT panels were used to cover the Melbourne Cricket Ground playing surface twice over.

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It was integral to the design to expose as much of the mass timber elements as possible. Given the scale of the project, we needed to balance the visual grade requirement with what was feasible both due to cost and transportation. Sanded structural grade CLT was selected for exposed areas.  On-site these were protected through construction and given a final sand and seal to deliver the required finish appearance.

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The use of mass timber construction along with its high-performance unitised facade system will substantially lower the building’s carbon footprint during its lifespan.

Case study 2: Monash University’s Gillies Hall

Totalling six storeys in height, with five levels of mass timber over a first-floor concrete podium, Gillies Hall is located at the highest point of Monash University’s Peninsula campus. Comprising 150 student beds in the form of studio apartments, two apartments for residential support, and ground-floor common spaces supporting the whole campus residential community, Gillies Hall wears its green credentials proudly.

It has achieved some impressive firsts for low energy buildings in Australia – when it opened in 2019, it was the largest Passivhaus Certified (PHC) building in the southern hemisphere and Australia’s first student accommodation built to PHC standard. It’s also one of Australia’s largest CLT buildings that also achieves PHC, and the use of CLT panels halved the embodied carbon compared with typical concrete construction.

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The project heralded one of the first entries of a Tier 1 builder into residential mass timber construction in Australia. This was significant, as the positive experience of Multiplex set the tone for other builders approaching timber construction. JCB also collaborated with Multiplex on the later La Trobe University project.

The project builds upon Monash University’s model of pastoral care with communal kitchens placed directly outside lifts on each floor to increase incidental bump factors and to celebrate the warmth of the exposed CLT structure and natural materials.

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The fantastic renewable properties of timber cannot be underestimated. Interestingly, based on the volumetric growth rate of Australian softwood plantations, the volume of timber used in the La Trobe University project (4500 cubic metres) regrew in 6.5 - 7 hours, while Gillies Hall (1800 cubic metres) regrew in only 2 - 2.5 hours.

In JCB’s viewpoint, mass timber use will continue to grow, and it will be a powerful tool for the industry to design and deliver the future of low carbon buildings.