INSPIRATION

Straw bale construction

"Straw bale construction uses baled straw from wheat, oats, barley, rye, rice and others in walls covered by stucco. Straw bale is traditionally a waste product which farmers do not till under the soil, but sell as animal bedding or landscape supply due to their durable nature. In many areas of the country, it is also burned, causing severe air quality problems. It is important to recognize that straw is the dry plant material or stalk left in the field after a plant has matured, been harvested for seed, and is no longer alive. Hay bales are made from short species of livestock feed grass that is green/alive and are not suitable for this application. Hay is also typically twice the price of straw.

This technique for constructing walls has been recently revived as a low cost alternative for building highly insulating walls. The technique was practiced in the plains states (of the USA) in the latter 1800's and early 1900's. Many of the early structures are still standing and being used. The technique has been applied to homes, farm buildings, schools, commercial buildings, churches, community centres, government buildings, airplane hangars, well houses and more.

Straw is also being used as a building material currently in sheet materials such as sheathing and wall panels. However, the approach of using bales directly, despite its history, is a new technique from a regulatory standpoint. The City of Austin recently passed a straw bale construction building code which is the fifth code enacted by a government body in the United States.

Building walls with straw bales can be accomplished with unskilled labour, and the low costs of the bales make this technique economically attractive. However, it is important to realize that the cost of straw bales will differ depending on what time of year they are harvested and how far they need to be transported. They are cheaper at the time of harvest rather than after they have been stored from the previous season and, of course, cheaper if they are transported shorter distances. Bales must also be protected from getting wet. Costs also begin to rise when one considers the type of stucco and its application. A mud plaster taken from site soil, applied by the owner/builder, and maintained by the owner is quite inexpensive, but may take a long time to apply. Cement stucco applied by a contractor is accomplished quickly and lasts a very long time without any maintenance, but also costs money. As with any style of construction, the more labour input by the owner and the less by the contractor, the lest costly it will be.

Two basic styles of straw bale construction have been used: post and beam construction with straw bale infill, and structural straw bale construction or 'Nebraska' style (the weight of the roof is supported by the bales)."

From the City of Austin's Sustainable Building Sourcebook

http://www.greenbuilder.com/sourcebook/strawbale.html

Some other sites with information on straw bale construction
http://www.i4at.org/lib2/strwbale.htm

Straw bale construction in South Africa

Jokes about the three little piggies aside, straw bale is becoming a viable alternative construction material in South Africa. Cape Town architect Etienne Bruwer has pioneered the use of the material in the country, using it to build his office in Constantia, Cape Town. Since then a number of projects have been built in the country, including a guesthouse in the Cederberg.

http://www.oudrif.co.za/straw.html
http://www.cce.ufl.edu/affiliations/green/straw.html

Case study

The house of Christiaan van Zyl, featured on this website is one of the braver experiments, being a load bearing structure. View a project description and photo album.

If you would like to have your straw bale structure featured on this website or registered on a national database, please send the project information to cdupless@csir.co.za.

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