Polyester strapping is one of the materials successfully used for the compression of straw bale walls. We use a 19mm wide flat polyester strap fitted every 450mm along the straw bale wall. With a breaking strain of 1,100 kg we can consistently gain 7% compression.
The compression achieved from the polyester strapping negates the risk of straw bale wall sinking after the roof is fitted, a problem that can be difficult and expensive to fix.
The strapping is safe to use, as it does not flick around in the air as does tensile wire. It is extremely cost effective, with most houses using one to two rolls of strapping at a cost of about $150 per roll. The heavy duty buckles, at a cost of about 30cents each, are fitted to each side of the wall. Fitting the buckles is quick and easy. The tool to tension the strapping is easy to use, and at a cost of around $150 are very affordable.
Not only is polyester strapping easy, low cost, and effective, it is environmentally responsible, as the embodied energy in the production of strapping is much lower than that of steel.