Strawbale pre-fabrication

Building homes out of straw stacked on-top of each other has a long tradition, largely in the United States. The drawbacks are the rough finish that takes time to render, and the potential for mold or water damage if not installed or maintained correctly. A new material has been quietly developing in Australia that is looking to make building with straw easier to get through council by standardising parts of it, and providing a load-bearing option that can be picked up by builders or owner builders.

For nearly 30 years, John and Susan Glassford have been involved in the strawbale building industry from their home in Ganmain in South West New South Wales, where they built and continue to occupy 7 small straw bale pavilions or pods, and began Huff ‘n’ Puff strawbale construction.

The advantages of strawbale, as listed on the Huff ‘n’ Puff website are that they:

• dramatically increase the efficiency of a solar-passive construction and can reduce the need for any heating and cooling equipment.
• because of their increased insulation, they allow installation of heating or cooling systems much smaller than those in conventional homes
• provide substantial savings in gas, electricity and wood-fuel bills
• are 30 times less energy-intensive than wood-frame walls to manufacture.
• straw can be grown in less than half a year in a completely sustainable production system.

Beyond private clients for whom they have built straw bale wineries, commercial buildings and houses they have held five-day workshops around the country, teaching people how to build their own straw bale homes. John is the founder and Charter President of AUSBALE and has been central to the development of the new sustainable construction method SITUPS* or Super Insulated Tilt Up Panels that is a relatively new development in strawbale construction.

Beginning in the quiet suburbs of Wagga Wagga, the first SITUP prototype building was born in 2014 after years of planning and experimentation. Based loosely on prefabricated wall-panels known as SIPS which are a modern alternative to traditional timber framed construction and function as the structural element for walls, roofs, and suspended floors. SIPS consist of two outer layers of Oriented Strand Board (OSB) sandwiched around an Expanded Polystyrene (EPS) core. SITUPS* are a manufactured insulated panel that uses as its core material waste agricultural cereal straw from wheat and other cereals commonly grown in Australia.

The SITUPS* is promoted as greatly reducing carbon emissions from new buildings through savings during manufacture and the operation of the building. Having been used in dozens of builds across the south-east, SITUPS* (a trademarked name for the prefabricated structural straw panels) can form the bulk of the external walls of a new build, and due to being prefabricated, and removing the need for expensive and time-consuming specific timber framing, SITUPS* is highly competitive to conventional building methods. SITUPS panels are now being produced in the Glassford’s factory in Ganmain and can then be rendered with lime and sand. For more information on the history of SITUPS* read this article in the Last Straw magazine.

Kirstie Wulf, of Shelter building design, has been working on a unique project near Tumbarumba, in the snowy mountain region of NSW. The clients were interested in using prefabricated straw panels, and making the most of passive solar design principles that would see their alpine home toasty. Still awaiting the final tick from the certifier for their performance solution, a must for every SITUPS* project at this stage, the panels are 2100 by 900mm by 350mm, performing much like full straw bales but knocking nearly 2-3 months off construction time.

Kirstie is excited by the upcoming project, a first for SITUPS* in an alpine region, and encourages more people to look to prefabricated version of natural materials for better ease of construction, permission, and cost. Though strawbales are relatively quick to put in, Kirstie says the most time-consuming part of the project is tying and tightening the bales and then infilling the gaps with cob or render to make the walls smooth and straight. By taking the work out of this project and having the load bearing boxes pre-filled, not only does it provide a smooth finish for the coats of render, but it circumvents the requirement of a traditional post and beam construction that is often needing to be specifically designed to suit strawbale builds, and hence is more costly than conventional timber/brick homes.

Similarly, Huff ‘n’ Puff are proud to discuss the Seymour (Vic) Huff’n’Puff Haus that has been designed by architect Talina Edwards from Envirotecture. The Seymour home is now Certified Passivhaus-Premium. There are currently only a small handful of Passivhaus-Premium projects listed on the Australian database and this is the first strawbale one.

While the work of Huff ‘n’ Puff, alongside Sam Vivers from Viva construction is looking to revolutionise the industry with prefabricated strawbale walls, there is a long way to go to get the broader industry, and codes up to speed on the value of natural wall materials for insulation, sound and health.

Photo Credit Marnie Hawson