Straw is one of the oldest construction materials in history, and has been used in many cultures to construct shelter. It is durable, cheap, renewable and easy to obtain, and it is also excellent for insulation. The straw used is often from barley, wheat or rice and is typically a waste product of farming that is usually disposed of or sold for animal bedding.
Aside from being economical and environmentally friendly, straw is considered to be an easy material to work with for unskilled builders. Using straw also gives a house a unique organic look that many will find appealing. Straw is inherently good for heat insulation, while also insulating against noise. With the coating of plaster applied straw walls makes them very resistant to fire.
Types of Straw Bale Buildings
Straw bales may be used with wooden frames to build a house where the frame and not the straw support the weight of the roof. In this case, the straw is used as a filling material. In other types of construction, the straw itself may also be used as the main means of roofing support. One drawback to the former method is that the wooden frames add to the cost of building and also may require skilled workers to install.
Building with Straw Bales
Evaluating the site on which the house is to be built, is of course, essential as an early step, as both orientation and the very design of the house will depend on the various qualities of the land itself. Insulation and avoidance of heat loss will, to a large extent, depend on the nature of land and where the house is situated.
One important task in using straw to construct a home is choosing straw bales of good quality. This means that they should be densely packed, clean and dry. It should be noted that in most places the cost of straw would vary depending on the time of year. Obviously, the builder will want to time their construction project for the time of year when it is most affordable and when the land is most suitable for erecting a building.
The amount of bales to be used in a particular design will have to be calculated. This is a less than precise part of the job due to the fact that bales, unlike more conventional building materials, tend to differ in size.
After the structure has been assembled, the straw will receive a coating of plaster, which may be clay or cement based. The result will be a much stronger, more durable material, which is able to handle a significant amount of stress.
For homes where the bales will be supporting the weight of the roof, the straw bales will need to be anchored, whether by driving a stake through them, or else by “corseting” with wire and the use of stakes on either side. In the case of the latter method, the stakes will be removed after the application of plaster as the plaster will fortify the bales and ensure that they remain in place without the use of stakes.
Areas of Concern with Straw Bale Homes
The straw bales should be kept dry at all times. If they are allowed to get wet the moisture could facilitate the growth of mould within the walls of the home. Another concern is fire. While the homes are very fire-resistant when the plaster has been applied, prior to that the bales are very flammable, therefore care will have to be taken during construction.
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