Building a home requires many choices. This especially applies when struggling with the tradeoff between economic and environmental. One of these choices is to use straw bales for walling.
Straw is a natural and local material in Waterloo. The use of natural and local materials decreases the green house gases normally associated with home production. Additionally, straw is considered waste by farmers so by putting it to use in home construction the straw is being up cycled. Straw bale homes can also reduce energy consumption by approximately 50-75%.
There are two methods that can be used: post and beam; and load barring. Post and beam is where a frame is built and straw is used as infill to insulate the house. In the load barring method, there is little, if any, framing. Rather, the straw is compressed to hold the house’s load. Commonly, straw of barley, wheat, rice, flax, rye and/or oats is baled and used for exterior walls. As with traditional foundations, concrete is used for the foundation to stop pests and moisture from getting into the straw. Curbs, railings made of two 2×3 boards, are nailed to the floor and used to sandwich and hold the straw bales in place. Framing is also used to hold the doors and windows in place until the straw bale walls are set and plastered. The walls are plastered using earthen, lime, and/or lime/cement mixture.
Straw is very inexpensive, however, the cost to construct a straw bale home varies based on location, techniques, size of home, and type of labourers (contractors, volunteers, or a combination). It is common to get whole communities involved in building a straw bale home resulting in a huge decrease in costs.
There are two common myths about straw bale homes that I’d like to clear up.
1.Straw is susceptible to fire.
When straw is used for walling, the bales are tightly packed so that if a fire does start, straw bale homes are more resistant to fire due to the lack of oxygen in the walling.
2.Straw bale homes are susceptible to pests.
It is extremely hard for pests to get through the plaster layers surrounding the straw. The likelihood of pests with straw bale houses is just as high as any conventionally built home.
To learn more check out:
Strawbale.com. A World Leader in Straw Bale Education. <http://www.strawbale.com/strawbale-faqs#efficient>. 2009.
Green Planet Homes. Introduction to Straw Bale Construction. <http://www.greenplanethomes.ca/about_strawbale.htm>. 2007.
“Load Bearing”, not “load barring”. Otherwise, an informative article.