Straw Bale Construction/Characteristics/Availability types and cost
Availability, types and cost
Straw is an agricultural waste product, a by-product of grain harvesting. Many different kinds of straw are baled and can be used for construction. Straw is widely available, and is generally an abundant, renewable resource. Relatively little energy is consumed in harvesting, baling and transporting bales to a building site. In bulk, straw bales are generally sold for close to the cost of baling and transport. Farmers will sometimes sell bales for under cost in order to clear storage sheds prior to a harvest.
In most regions, straw is baled only once each year, and so must kept dry and stored for use at other times of the year. Straw production and demand is relatively constant, however high demand for bales used for erosion control following forest fires can create a temporary shortage of bales.
Bales are rectangular compressed blocks of straw, bound by strings or wires. Straw bales come in all shapes and sizes. Rectangular bales are the only bales suitable for building. The round bales that are now becoming popular require re-bailing before use but this is not recommended. Three string bales (585x405x1070 mm) common in western USA have an average weight of 29 kg. The two string bales (460x350-450x960 mm) which are common in the rest of USA and most of the world are easier to handle and have a weight ranging from 15 to 19 kg.
Besides these traditionally sized bales, big jumbo bales are also becoming popular. There are basically two sizes in use. The real jumbo is 1200x760x2400 mm and the mini-jumbo is 800mm wide and available in various lengths and heights depending on the bailing machine used. The jumbo bales are appropriate for bigger industrial buildings where they show definite advantages due to their high load carrying capacity of up to 3 t/bale for the 1200mm wide variety. Only machine handling is possible due to their weight. Greater stability and the bigger size of Jumbo bales compared to the conventional bales favors rapid and easy construction.
Small bales range in price from 1.50 USD per bale to 6USD per bale. Prices go up rapidly when you take into account transportation. Jumbo bales, including transportation, range in cost from 15USD to 30USD per bale. This depends upon when you purchase the bales, how far they need to be transported, and type of bale - whether it's wheat straw, flax straw, or rice straw. Different "waste" products have different values for farmers and some are less usable than others for agricultural purposes.
The best way to get an idea of prices in your area is to look in the Worldwide organisations and contacts section of this book. Of course if you find some useful information, come back and add it to this page.