Durability characteristics of straw bales in building envelopes

Cereal straw, including wheat, barley and rice, offers a renewable and sustainable resource stream for a variety of construction products, including compressed board panels, thatched roofing and bales. The successful use of straw bales as thermal insulation within the external envelope of buildings has been demonstrated by the increasing number of successful contemporary projects around the world. However, the warranty, insurance and financing of such projects is often still not as straightforward as competing solutions, which can be attributed to concerns relating to the long-term durability of the straw. This paper presents findings from an on-going experimental study into the condition monitoring of modern straw bale construction, and also reports on a study investigating the degradation behaviour of wheat straw cyclically exposed to elevated humidity levels. The findings of the study provide encouraging insight into the robustness of straw bale construction.