There is no good or bad material, just material well used or badly used

Straw Bale in China Straw bale construction can be an excellent solution, but at the same time it is important to recognize that it is not an easy technology and the possibility to commit fatal errors are great. During a study visit to a project of rural construction in the north-east of China, bordering Siberia, much was learned about this technology as well as the opportunity to have seen interesting and good applications of it. 

Linda Zhu, director of this project that has built more than 600 houses during the past seven years states clearly: the must be four preconditions to be able to carry out a successful social project with this technology…

  1. cold and dry climate
  2. abundance of straw in the region
  3. financing (Government, NGO's, etc.) to promote the technology
  4. need for housing

During the week of the visit there was much opportunity to discuss these and many other aspects and the architect Kelly Lerner who has guided the project since it's beginning has helped to transfer not only the positive aspects of this technology, but also it's limits of application.

A construction with straw bale walls usually isn't cheaper than other constructions like fired clay bricks or hollow concrete blocks, and possibilities for self construction are limited. It was noticed that there are many steps to take to assure that the straw doesn't deteriorate after a few years. This begins with the selection of the raw material….all straw is not equal. There is straw that lends itself to making bales and there are others that don't. For example, if you build your house with alfalfa straw you are creating a food court for rodents, also there are straws that deteriorate quicker than others.Straw Bale in China

The most critical problem is to prevent the decomposition of the straw and creation of fungus inside the walls. Plastering the walls is a special art; it's complicated, tedious and expensive, as there are various centimeters of thickness that have to be applied in various steps. The exchange of humidity in the walls have to be guaranteed to certain point and Portland cement mortars are dangerous as they tend to retain humidity in the walls…

Let´s not forget, the public in general and mainstream builders in most countries prefer to use Portland cement mortars, and its very likely that the house at some moment will be treated with a cement mortar, which does not prevent humidity from entering the walls (water always finds it way in) and maintaining it. This house will certainly have its problems…

Why build with straw?
During the past few years many have been thinking of building houses with straw bales. We have asked ourselves which would be the advantages of this material. Is it the cost, the climate or would it be that this construction is less damaging for the environment?

In Siberia, Manchuria and other regions with very cold climates there is clear advantage: straw is a very good insulation material and saves heating energy. In the project visited there has been a saving of 68% of coal. Just to be aware of the magnitude of this, a normal family burns between 40 and 60 tons of coal yearly! But in moderate climates this degree of insulation is not needed; fired clay brick, adobe or rammed earth walls provide enough insulation.

The project directors insisted several times that construction with straw bales is not cheaper than using 50cm thick brick walls, even considering that there is much straw in this region and the raw material has no cost, as afterwards a machine is needed to produce the bales. Lately In the United States and Canada this type of construction has become popular among environment activists.  Comparing the embodied energy in the straw bales with a brick or concrete wall, there can be a significant saving. Although this saving can be easily lost if thick lime or cement mortars have to be used, and if the straw bales have to be transported a long distance.

Why not build with straw bales?
This technology is not for trial and error… the errors become too expensive. If the straw begins to deteriorate, if it is invaded by fungus or serve as a hostel for mice, rats and other rodents, its difficult to find a viable solution. Demolish walls and rebuild would be a disaster that no builder would like to experience.

As the great advantage of this construction is its quality of insulation, it's evident that warm climates are not its area. In general one can say that this technology has many parallels with earth constructions. Adobe and rammed earth walls have to be protected against rain and humidity in general. This applies with greater intensity to straw bale walls.

Experiences on different levels
The oldest houses built with this technology are more than 100 years of age and there is a great number of architects and builders that dominate the technology, as well as a large amount of books on the technology. Those who want to build with straw bales must inform themselves very well nd be prepared to find consultancy so as not fall into fatal errors.

Straw Bale in China
You are here: Home Past editions Edition 22 - October 2006 There is no good or bad material, just material well used or badly used

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