The Success of Straw Bale Construction

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-By Jaime McKee

For centuries, people around the world have been building homes out of straw. Historically, reeds, grasses and straw have been used in thatch roofing, as wall insulation, and woven into flooring materials; following the invention of baling machines in the late 1800s, the compact, easily managed bales enabled walls to be constructed out of this renewable and versatile material. Far from being an outmoded building technique, straw bale construction once again has a place in Australian home design, as eco-pioneers and leading edge construction firms seek out sustainable alternatives to traditional materials.

Straw is the dry stalk left in the earth after the harvest of wheat, barley, rye, rice or oat plants and is traditionally considered a waste product, to be burned or baled and sold for animal use. A non-toxic building material with low environmental impact and superior insulating properties, it is generally used in one of two ways in home construction: structural straw bale construction sees the weight of the roof supported by the bales themselves, offering a simpler build, while post and beam construction supports the basic structure with conventional timber, with straw bales filling the spaces. In either case, straw bale walls are typically finished with cement stucco or earth-based plaster, sealing them from the elements and allowing for great flexibility in design. Straw bale walls can be square or rounded, uniform or undulating, with niches, ledges and windows built in as desired.

Extensively utilised by enterprising homeowners in the United States, straw bale homes have come a long way since their early incarnations. While some dozen or so Australian examples persist from the 1930s, the country’s first modern straw bale building was constructed by Bill Mollison in 1993 at Tyalgam’s Permaculture Research Institute in NSW. In 1995, Grass Roots magazine published an article on the concept, and straw bale building took off from there into Queensland, Western Australia, New Zealand, and beyond. With the word and skill set spread primarily through sustainable living networks and community-based workshops, the practice of building with straw is one that has evolved with time, research, experimentation and testing.

The benefits of building with straw are many. Straw is a renewable resource, yet one which often goes to waste. It is estimated that in New South Wales alone, rice farmers burn over 600,000 tonnes of rice straw annually, releasing 30,000 tonnes of CO2 and 2,000 tonnes of particulate matter into the atmosphere in the process. The same volume, meanwhile, could produce approximately 48,000 straw bale homes – representing a thrid of all new homes built in Australia each year – whilst substantially reducing greenhouse gas emissions.

Straw also has excellent insulating properties, performing very well in sub-tropical and temperate climates. With an R-value ranging from R4.8 to R9 for a standard bale, straw bale walls have over twice the minimum recommended R-value for the wall of a house in most parts of Australia and New Zealand. Combined with passive solar design, a straw bale house could substantially reduce the amount of energy – and expense – required to heat and cool a home throughout the year. Similarly, straw bale/mortar wall structures have also proven to be exceptionally resistant to fire. The straw holds enough air to provide good insulation but, as the bales are firmly compacted, they don’t hold enough air to permit combustion. In tests, straw bale homes have actually been shown to provide superior fire protection over many conventional materials.

Finally, homeowner participation and capacity-building is a key advantage to straw bale construction. With a strong network of local knowledge-holders and an abundance of web-based and video tutorials, homeowners have the opportunity to access all the information they need to apply their own labour to the building process, allowing them to save money, customise their homes, and gain skills along the way.

If building one’s own straw bale home sounds a little intimidating, however, there are a number of specialists within Australia and New Zealand lending their expertise to the process. In 2002, Ausbale (The Australasian Straw Bale Building Association) was born out of Wagga Wagga’s International Straw Bale Building Conference. A group of building industry professionals, researchers, owners, builders, and interested citizens, Ausbale is an association dedicated to contributing to the “growing movement towards better, smarter, ecologically sustainable, non-toxic and beautiful buildings”. Its website acts as a hub for discussion and advice as well as providing technical specifications, international building codes, photo galleries and contact information for professionals in the field.

One such industry professional is Authentic Straw Bale Construction Ltd, a New Zealand-based company bringing over 35 years of home-building experience to alternative construction methods including Straw Bale, Compressed Earth Block and Rammed Earth walls. Making the move to sustainable materials “to accommodate a growing market sector”, the company’s approach aims to create “affordable homes and buildings that are not only beautiful with a natural character, but also environmentally friendly”.

In a similar vein, Huff ‘n’ Puff Strawbale Constructions has been providing professional straw bale construction since 1998. Based in New South Wales, the company is owned by Susan and John Glassford (John is Ausbale’s founder and Charter President), and conducts instructional workshops and courses which are open to the public. Environmental Building Solutions, operating out of Canberra and Southern NSW, is another innovative firm offering a range of sustainable designs including straw bale construction.

As more and more homeowners look to alternative home-building techniques – and increasingly take their home-building into their own hands – and a growing collection of companies aim to meet the demand for sustainable housing design, we can be assured of seeing straw bale construction on the horizon for years to come.

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November 21, 2018, 3:44 AM AEDT