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    RMIT building by H20 Architects: the seed for timber’s resurgence in large façade applications

    Geraldine Chua

    The use of timber on Australian commercial and institutional facades has grown substantially in the last decade or so, a trend which might be traced to roots in Berlin, Tasmania, and Melbourne.

    The last location, Melbourne, is possibly the most important if you are considering local growth in timber façades, and can be narrowed down to a particular structure: the 5,200sqm, three-storey RMIT University Textile Facility designed by H20 Architects.

    Completed in the late 1990s, the building’s façade features an interlocking grid timber patterning that changes with varying light conditions, inspired by the weaving and rafting programs that take place within. But it was the use of the timber façade as an operable, external ‘rain screen’ separated from the actual Tyvak enclosed building envelope by a 75mm air gap so that it also performs as a thermal chimney, which made it stand out.

    Raw precast concrete is used on the ground floor exterior, but western red cedar panels clad the rest of the building. The ‘double skins’ system on either side of the thermal chimney, which limit heat transfer to the building interior, was jointly developed with the builder, engineers, the Timber Promotion Council and leading northern European researchers in timber façade systems. Even today, the façade’s top and bottom can be closed off in winter, and opened in summer to facilitate summer cooling.

    “The project set new benchmarks for the use of timber as a façade cladding on large scale institutional and commercial buildings in this country,” says Tim Hurburgh, Director of H20.

    “RMIT as an educational institution focused on research and innovation, and supported what was at the time a unique and pioneering project. Sixteen years after completion we believe their goals have been met.”

    And they have. Fading naturally with age and weathering to a silky grey, the façade does not have any applied finishes as research had indicated that when treated with applied paints or coatings, these materials in fact broke down. The western red cedar has also stood up to its claims.

    “[Western red cedar] was chosen because of its superior weathering and performance characteristics from both constructability and risk management viewpoints, specifically: knot free, dimensionally stable, and stable weathering characteristics,” Hurburgh explains.

    He also points to the product’s stain free, stable and reduced tannin content. Another upside was the material’s established reputation – using a product that was manufactured and supplied as part of a well-established international operation was integral when it came to convincing the University to try ‘something new’.

    On why H20 chose timber in the first place, during a period when timber was still an uncommon product for large facade applications in Australia, Hurburgh points to the other two locations – Berlin and Tasmania.

    “My personal experience working with timber products in Germany in the mid 90’s (whilst working on the Australian Embassy, Berlin) was an eye opener. Timber usage there and elsewhere in Europe is extensive on a wide range of building types for cladding, window and door systems, and screens in a climate much more severe and with much greater extremes than in Australia,” he says.

    “Secondly, returning home and re-examining the wide spread extent timber structures in my own home state of Tasmania – including the world famous all timber Oast houses in the Derwent Valley. I thought there was an opportunity to re-examine our attitudes to the use of timber for larger scale institutional and commercial applications.”

     

     

     

     

     

     

     

     

     

     

    Hurburgh was part of the team at Bates Smart to refurbish the 100-year-old building in Berlin that was purchased by then PM Paul Keating to become an Australian embassy following German reunification. The building’s double-glazed window systems in timber that had endured years of heat and snow inspired his work with timber. Image: Bates Smart

    Valleyfield, New Norfolk: The Derwent Valley’s famous Oast Houses were constructed in the second half of the 19th century and early years of the 20th with timbers including framing, flooring, split ‘weatherboards’ and roof shingles that were milled and sawn, says Hurburgh. Today, they continue to be amongst the largest all-timber structures in the Southern Hemisphere.

    Possibilities are endless, but timber rain screens still work

    Deakin University International Centre and Business Building by H20 Architects

    Since the completion of H20’s most influential building, the use of timber as an external wall material has grown dramatically. According to Stephen Mitchell from the Timber Development Association and WoodSolutions, a lot of this use can be found in projects ranging from health facilities, multi-storey apartments and community buildings, to retail and education buildings.

     

    The Dandenong Mental Health Facility in Melbourne, designed by Bates Smart in collaboration with the Irwin Alsop Group, is one building that understands and embraces timber for its profiles. 

    Hardy, low-maintenance blackbutt chosen for the external cladding and exposed columns put to rest durability concerns, but more importantly helped to create a non-institutional, warm and tactile sensory experience for patients, staff and visitors. 

    Images: Bates Smart

     

    The visual quality of timber was also one of the reasons why the material was chosen for the Monash University Student Housing Project by BVN. Over 40 per cent of the project’s façade is covered by a full height vertical ship lap spotted gum panel comprising individual 120 x 20mm boards, with the timber punctuated by the horizontal edges of exposed flat concrete slabs. Spotted gum battens, measuring 70 x 45mm, were also used to create vertical sun shading battens that provide both a protective façade veil and a strong identity at the central ‘nexus’ of each building.

    Images: John Gollings

    Spotted gum was selected because it would age gracefully, and evoke a sense of domesticity that breaks down the large facades into smaller segments to prevent the buildings from being large, bland and overwhelming. 

    Other notable larger-scale projects that have employed timber on their facades include Library at the Dock by Lend Lease, Australia’s first CLT constructed public building, whose façade consists of a recycled ironbark and tallowwood timber rain screen that complements the promenade decking. The Commons by Breathe Architecture employs timber’s aesthetic and tactile qualities to achieve the project’s pared-back aspirations while prizing its low-carbon footprint properties.

     

     

     

     

     

     

     

     

     

     

     

     

    Left: Library at The Dock, image: Diana Snape. Right: The Commons, image: Andrew Wuttke

    The pioneers of the use of timber facades have not halted their use of the material either. H20’s recent Australian Grains Genebank (AGG) project, like its predecessor, features a western red cedar external cladding to the rain screens of the exposed walls and soffits.

    Caption: A custom 138 x 19 mm chamfered Dress All Round (DAR) board was utilised for the cladding and soffits, which was installed upon a western red cedar sub frame over a Colorbond sheet steel skin.

    Carrying images of ancient crop circles and modern plant anatomy, the timber panels were chosen not just for their looks, but because they were the most flexible and ‘low-tech’ thermally efficient buffer between the elements of the Wimmera Plains, and the building, which stores seed samples and houses freezers that operate at -20 degree Celsius.

    “The selection of a timber clad façade at the AGG was informed by the desire to specify a thermally efficient material that was at the same time sensitive to the local context and also an unexpected choice for an industrial facility,” says Hurburgh.

    “The timber rain screen…alleviates the high solar loads characteristic of the semi-arid climate that could otherwise only be achieved with engineered composite products.

    “The reduced carbon footprint of timber was also a complementary message to the sustainability agenda of the facility and the Department of Environment and Primary Industries. All specified cladding was PEFC and FSC certified.”

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