Strawbale Construction: Sustainable Development at Its Best
As a former member of an ecovillage– an offgrid community built around principles of ecological sustainability– I’ve had the privilege of helping to design and construct several houses and outbuildings using strawbales as base materials. I have always been deeply intrigued by the simple, beautiful results created by strawbale construction.
Strawbales used for construction are tighty bound “bricks” created using the dry stalks of grain crops. Because the stalk is inedible to humans and usually discarded, straw bales are very inexpensive, and are an earth-friendly building material because they utilize an organic by-product of the agricultural industry. Strawbale is one of the most popular construction materials for sustainable development projects.
Compared to other construction materials like standard brick and wood, strawbale buildings are remarkably easy to erect, and are often hand-built by people with no prior construction experience. I have witnessed a group of five people construct a load-bearing, single-room strawbale house in as little as a week.
The simplest form of strawbale building is the classic load-bearing structure, also called “Nebraska Style” by fans of strawbale construction. Load-bearing strawbale houses are as easy as 1-2-3 to assemble. A basic foundation is laid using rubble, cement, or compacted earth. Iron rebars are laid to secure the foundation, and rectangular strawbales are laid like bricks to create thick, insulative walls. Finally, a roof is placed on the building–the most difficult part–and the walls are plastered with stucco, lime, or cob mixture.
More complex strawbale houses sometimes require timberframing, which is the process of using wooden posts and beams to reinforce the structure. Timberframe strawbale houses are easier to roof, have a reputation for lasting longer, and make it easier to install features like lofts and upper floors. Post-and-beam style is the most common method I have seen used for structurally reinforcing a strawbale building.
Completed strawbale buildings are extremely well-insulated. The thick walls of a strawbale home or outbuilding heat and cool efficiently owing to their denrse thermal mass. Strawbale houses stay delightfully cool in summer and surprisingly warm in winter. This has an additional ecological benefit because it allows for a significant reduction in energy to heat and cool.
The only difficulty that I have experienced regarding strawbale construction is the potential for mold and pest infestations during the time of construction. After the building is completed, the bales can not be accessed by mold or pests, but they remain vulnerable to these complications if bales are left uncovered for extended periods during the construction process itself.
Strawbale construction is quickly gaining in popularity as consumers strive for more sustainable forms of development. If you are interested in learning more about strawbale construction and other techniques for green design, visit your local library or contact a green activist organization in your area.
