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GSBN:Re: Inquiry about jumbo bales

At 03:25 PM 12/8/2007, Olivier wrote:
I'm interested in big straw bale (900 mm x 1200 mm x 2000 mm, approx.)
construction......... Do you have run tests on compression loads,
etc. I'd like to see a
Hooke curb  or a Young modulus if available.  Olivier TURLIER,
Marseille, France

Dear Olivier --

I am writing a book which includes two load-bearing jumbo-bale
buildings designed and built by architect Werner Schmidt in
Switzerland.  I don't have the exact technical data you request, but
be assured that these bales are being used successfully as structure
and super insulation. (Werner is completing the 11th jumbo bale
building this year, one recent building is 3 1/2 stories high.) He
also did perform some load-bearing tests before he started building
with these bales.  Below is a draft of my book text about the testing
that he did.  FYI, Werner's website is:
<a  target="_blank" href="http://www.atelierwernerschmidt.ch";>http://www.atelierwernerschmidt.ch</a>  (Perhaps he will also reply to
this message, if he is not too busy.)


......his designs make use of the strengths of jumbo-sized straw
bales, which average 8 feet long, by 4 feet wide, by 3 feet high (250
x 125 x 70 centimeters).

To construct his first strawbale house, Werner needed to be sure the
wall system would structurally support two floors, and handle a
winter in the Swiss Alps. "We had to calculate a 650
kilogram-per-square-meter, snow-load on the roof," says Werner. That
snow adds about 133 pounds per square foot to the weight the
structure must support.

So before he designed the Braun home in Disentis, Werner tested the
compression of jumbo bales utilizing pallets of bricks, each weighing
a metric ton (which is 2.2 U.S. tons, or 4,400 pounds.)  He stacked
six pallets on each bale, which is nearly 2 tons per square meter --
or about 786 pounds per square foot.  The bales squished down under
the weight, and compressed  (how much?)  After three weeks they
removed the weights, and the bales rebounded to their original size
and shape.

Later Werner had the chance to again test jumbo bale compression
strength, in the University Laboratory at Chur. They applied 40 tons
of weight on a single jumbo bale without breaking the strings. In
American terms, that's about 5,240 pounds per square foot! These
tests gave Werner confidence to move forward with his design.

These giant bales have a huge insulating power, too -- a European
U-value of about 0,05 W/m2K, which translates to R-113.4 in U.S.
terms. It's a bit like living in a thermos bottle. During
Switzerland's long cold winters, "it is often minus 20 degrees to
minus 30 degrees Celsius (-4 to -22 degrees Fahrenheit), but if the
sun shines, it's no problem to heat the house," says Werner.

Best regards,
Catherine Wanek

Black Range Films &amp;
Natural Building Resources
119 Main St. , Kingston, NM 88042
575-895-3389 / fax 575-895-3389
toll free: 800-676-5622
<a  target="_blank" href="http://www.strawbalecentral.com";>http://www.strawbalecentral.com</a>

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