As a building medium, the use of straw and clay mixtures has been widely practiced for thousands of years. Perfect in the extremes of temperature, strawbale houses provide a quiet, wind-proof, and temperature efficient barrier from the natural elements. In a country with such huge seasonal variations in weather as Australia, strawbale homes offer the perfect solution for building construction in such a dramatic climate.

Strawbale Building

Strawbale building has been around for much longer than Straw and Clay! There are buildings of this age still standing in France ,Scandinavia and the usa.

Strawbale building was cheap and easily practiced. The straw was readily available and usually a waste product and therefore it’s cost was small. It’s excellent thermal insulation properties made it the ideal material in colder climates.

Generally two different construction methods are used. Load-bearing strawbale construction, is a technique in which the strawbale walls carry the entire roof load without any other structural members being used in the building of the house.

Infill construction involves bales being used to fill the voids or spaces between load bearing timber or steel posts and beams.

Generally speaking infill construction is easier and less dependent on weather or other external influences. The roof can be raised before wall raising is commenced and therefore weather protection is guaranteed once the straw work starts.

Load bearing construction requires all external walls being raised before the roof construction can commence. This places quite large pressure on the building team since the straw bales are being exposed to the elements until the roof covering is on.

Spray Rendering

Clay rendering is complementary to straw bale building due to the ability of the clay to absorb and release moisture in addition to having excellent adhesion to the straw bales without requiring any further netting or support structure.

Our spray rendering technique onlye uses clay, with a sand or aggregate added for strength. Generally we do not add cement on the basis that this would diminish the breathability of the clay render, without enhancing the product in any crucial way. This permeability is important so that moisture that may penetrate the render can also pass through this render again to evaporate. If any cement content in the render becomes to high this breathability is no longer possible.

In addition, cement render does not bond well with straw and therefore metal netting like chicken wire or similar is used to aid the bonding.

In order to make this rendering process economically viable we recommend to spray the first two coats of render. The advantages are a better key of the render to the bales and a higher build up of render per render coat ( up to 40mm).

Links

We're passionate about the increasing use of strawbale techniques in Australian building. Here are a few sites where you can learn more about straw...


Ausbale - an Australian lobby group for straw bale building.

Blue Mountains Permaculture Institute - permaculture website for the blue mountains run by our local gurus Liz Bastian and Rowe Marrow.

Greenpeace Article on PVC - why PVC is bad news for you and everybody else.

Ontario Strawbale Building Coalition - an American straw bale site. Very active and informative.

ACF Greenhome - an eco foot print calculator.

Earth Building Association of Australia - everything to do with regards to building with earth.