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Basics of Straw Bale Building
What is it? Straw. A waste agricultural byproduct, compressed into blocks and bound with polypropylene string. It can be either load-bearing or as an infill wall material.
Pros of Straw Bales
It is made from a waste material, is completely non-toxic and has a high insulating value, as much as R-45 for a wall. You just plaster it inside and out and you have a durable wall that is as fireproof as a conventional wall. (See Ted Owens' New Mexico house in TreeHugger) One strawbale owner says "Strawbale buildings have a gorgeous feel. The thick walls evoke the presence and security of masonry walls of bygone eras. A timeless quality of building is evoked."
How Green are Straw Bales?
Did we say it was made from a waste material? It really doesn't get much greener.
Cons of Straw Bales
Water. If any moisture gets in the wall it can ruin it; designers need to put deep overhangs to protect it and use a breathable plaster so that moisture can get out. Some have suggested that it perhaps is inappropriate in damp climates, and that it might get moldy and not last very long, but they have been doing it for years in the UK.
Fire. Once it is finished, tests have shown that it is more fire-resistant than conventional frame construction, but loose straw on the ground, cut bales and stacks of bales are all highly combustible.
Where do I get it?
At farms across North America. You need the tools to compress it and bind it into blocks. In the UK they have developed systems to prefabricate panels, but so far as we can tell, these have not reached North America.
How Much:
It should be just about free, and almost all of the cost is labour. However the plastering of it is time consuming, resulting in an overall construction cost estimated to be 20% more than conventional construction.
