Straw is considered an agricultural waste product, which makes it quite inexpensive when people want to use it as a primary house building material. Straw bales, covered in stucco have been used in the dry prairies for hundreds of years. It is now becoming a serious alternative house building technique even outside of the prairies.
We visited the building of a demonstration house in Guelph, Ontario called Home Alive. This house was built for and exhibited at the 2003 Toronto National Home Show. There are several ways to build straw bale homes. This one uses the stack of bales as the structure itself of the home. Two years ago we took a look at a Montreal home where straw bales were used as filler between 2x4 construction.
After building the home, a mesh is sewed to the outside of the wall and then one inch of cement lime plaster put over the mesh. The last photo shows a finished wall waiting to cut out the window.
When straw is compacted into a bale it is literally fireproof because there is not enough oxygen to support combustion. It also has a high R factor, is great for sound proofing, is cheap and lends itself to construction with unskilled labour. Typically straw bale houses are built with lots of volunteers.
Straw is potentially susceptible to rot if there are moisture problems and hence the CMHC is doing a fair amount of research into the consequences of using these building techniques outside of their native habitat of the dry prairies. No-one should get into build something out of straw without doing a lot of research, but the internet itself abounds with straw bale sites offering guidance and critism.
Harvest Homes in Guelph, Ontario is hoping to begin manufacturing pre-fabricated straw bale walls to bring this old tradition into the modern field of modular housing. That also means that they will be able to build the walls under conditions of controlled temperature and humidity.