Monday, May 5, 2014

Strawbale Construction

By Michelle Harris

Straw bale construction is perhaps my favorite alternative construction method for Southern Illinois. It’s an available local resource and by using straw bale in construction reducing waste of an off product. An example of a straw bale house is the Makanda Inn. I’ve not been in the Makanda Inn but from the online account of the experience I read at www.earlywarn.blogspot.com the facility appears to be beautiful and comfortable. The process of creating a straw bale home is what makes the building less expensive than traditional construction. Straw bale is easily done with a group of workers who need not have professional construction experience. I am fascinated by the possibilities of using the Earth as a resource for construction.
 To familiarize myself with straw bale construction apart from hearsay that I’ve gathered from a friend who is building a straw bale underground house, I read How Stuff Works’ (http://home.howstuffworks.com/home-improvement/construction/green/straw-bale-house.htm)take on straw bale homes. The history of straw bale in the U.S. began in Nebraska due to limited wood resources on the prairie fields. Europe has had an extensive history of straw bale construction which has strengthened into even having commercially built public straw bale facilities. You can view the process here: http://www.baubiologie.at/wp/strohballenbau/strohbaugalerien/impressionen/ .

The truly amazing thing about straw bale construction is the ability for the straw to be structural in addition to insulatory. The structure of the interlocking straw bales operates like legos and is self-supporting. This is called Nebraska style of straw bale. There are some structural limitations to this construction for load bearing walls. The other construction method is post and lintel straw bale.

load bearing straw bale construction
post and lintel straw bale construction

Straw is different from hay. Hay will decompose more quickly and has a leafy texture. The moisture content of straw is typically lower. Straw will work out the moisture content out. The plaster prevents moisture from accessing the straw and provides a means of wicking the moisture away from the straw. Ventilation is very important to the life span of a straw bale building. 



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