Compressed Straw Board (CSB) is a wall construction and lining material made in a continuous process by heating straw under pressure in a Stramit International machine.
A solid board is produced which is 100% pure straw, without extra binder, the lignin in the straw being sufficient to act as a binder during the process. Normally it is covered with a paper cover during the process.
CSB is produced in solid self supporting boards in thicknesses of 40 or 60mm and 800 or 1200mm widths, at selectable length between 1.5 and 3.9m.
CSB is used to face the internal wall and ceiling surfaces of buildings by fixing to the structure, and can form self supporting internal walls (partitions). It can be plastered in clay or gypsum, to a fine finish.
CSB has a thermal conductivity value of 0.1 and as such is part of the thermal function of a building, usually supplemented by less dense insulation. It is vapour permeable and contributes to the moisture balance within a building, buffering changes in air humidity. Being of medium density CSB acts as a sound absorber and contributes to acoustic insulation between rooms in a building. A single 60mm board with a plaster finish provides 60 minutes fire resistance.
CSB demonstrates low embodied energy. It is 95% straw – a waste product of agriculture gathered into bales and transported to the processing plant. Processing CSB therefore uses little electricity.
Carbon Dioxide is sequestered at the rate of 1.5kgCO2e/kg or 30kgCO2e/m², considering only the straw component. Being a natural biological material the VOC content is negligible, contributing to a healthy indoor environment.