Straw Bale Construction

Lisa Patrick, Matt Tosi, Anna Kovaliv

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

Self-Supporting Method

• 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

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?

• Will my house rot? No!

• Walls are breathable enough that condensation is limited

Concerns?

Questions?

Bibliography

• www.foodforest.com

• www.piedrasyolas.com

• www.buildinggreen.com

• www.pangeapartnership.org