What is it?
• Environmentally friendly building method that uses straw bales as structural elements and/or insulation
What is it?
• Straw is the stalk left over after cereal crops such as rice, wheat, and barley are harvested.
• Has been used in construction ever since humans have created shelter
• Used for centuries in Asia and Europe, began as a plaster mixture
History
History• First used in the United States in the Great
Plains due to the lack of timber
• Making a comeback because of high amount of benefits
Self-Supporting Method
• “Nebraska-style”
• Use bales as if they were large bricks, compressed with heavy material
• Plastered on both sides
• Usually limited to one story
• Use bales as insulation within an existing frame
• Plastered on both sides
• Allows for any size house to be built
• Most widely accepted method in the United States
Post & Beam Method
Benefits
• Green Building method using an annually renewable resource
• Uses less energy consumption to harvest, produce, and transport bales than conventional methods (timber)
• Directly supports local economy
Benefits
• Utilizing a waste product of an existing industry
Annual carbon monoxide production from power plants and straw burning
SOURCE TONS BURNEDTONS OF CARBON MONOXIDE
RICE STRAW 1 MILLION 56,000
WHEAT STRAW 97,000 5,000
POWER PLANTS 25,000
California Agricultural Magazine, Vol 45, (1991)
Benefits
• Energy efficient due to high insulating value (R-value)
• Walls constantly breathe, circulating air, while still providing superior thermal insulation
• Walls are very soundproof
Concerns?
• Is my house going to burn down? No!
• The bales hold enough air for good insulation but compacted tightly enough to discourage combustion.
• High silica content in straw impedes fire
• The plaster can reach temperatures of 1850 degrees F for 2 hours before cracking.
• Will bugs or rodents eat my house? No!
• There is no nutritional value in straw
• Burrowing can be limited by careful plaster application and tightly woven wire mesh surrounding bales
Concerns?
Bibliography
• www.foodforest.com
• www.piedrasyolas.com
• www.buildinggreen.com
• www.pangeapartnership.org