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<TITLE>RE: [Strawbale]Some loadbearing compression ideas/questions</TITLE>
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<P><FONT SIZE=2>Hi All,</FONT>
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<P><FONT SIZE=2>With regard to pre-compression, creep, pre plastering post plastering and cyclic vertical loading (snow loads) you might want to look at that part of the test we did as EBNet. Go to www.ecobuildnetwork.org and click on the straw bale testing program link in the upper left hand corner. This will take you to some of the reports from the tests that we conducted. The test to which I am referring is title "load-bearing and Creep".</FONT></P>
<P><FONT SIZE=2>Best of luck as we all discover how best to build plastered straw bale structures,</FONT>
</P>
<P><FONT SIZE=2>Tim</FONT>
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<BR>
<P><FONT SIZE=2>Tim Owen-kennedy</FONT>
<BR><FONT SIZE=2>Vital Systems, Natural Building & Design, Inc.</FONT>
<BR><FONT SIZE=2>888.859.6336 PO Box 751, Ukiah, CA 95482</FONT>
</P>
<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: strawbale-admin@amper....muni.cz [<A HREF="mailto:strawbale-admin@amper....muni.cz">mailto:strawbale-admin@amper.ped.muni.cz</A>] On Behalf Of Stewart Hargrave</FONT>
<BR><FONT SIZE=2>Sent: Thursday, May 05, 2005 4:02 AM</FONT>
<BR><FONT SIZE=2>To: strawbale@amper....muni.cz</FONT>
<BR><FONT SIZE=2>Subject: Re: [Strawbale]Some loadbearing compression ideas/questions</FONT>
</P>
<P><FONT SIZE=2>On 27 Apr 2005 at 11:15, rikki nitzkin wrote:</FONT>
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<P><FONT SIZE=2>> HI all,</FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> Some thoughts about compression for you tecnical people. I have been </FONT>
<BR><FONT SIZE=2>> thinking about these techiniques that are popping up as ways to reduce </FONT>
<BR><FONT SIZE=2>> compression on loadbearing walls. Specifically the techniques like those </FONT>
<BR><FONT SIZE=2>> used by Tom Rijven, or the man in ávila: they use clay paster on the walls </FONT>
<BR><FONT SIZE=2>> before or during the wall-raising. This solidifies the walls and they donīt </FONT>
<BR><FONT SIZE=2>> compress. This has obvious advantages because it protects the wall at once, </FONT>
<BR><FONT SIZE=2>> and you donīt have to leave gaps above or below the windows and doors, and </FONT>
<BR><FONT SIZE=2>> if you build the wall well you donīt have to worry about uneven compression, </FONT>
<BR><FONT SIZE=2>> etc. SOunds good, huh? But the other day I was thinking (I do that once in </FONT>
<BR><FONT SIZE=2>> a while) and I thought to question: A compressed wall is sure to be </FONT>
<BR><FONT SIZE=2>> stronger, no? it may be more comfortable avoiding compression, but will it </FONT>
<BR><FONT SIZE=2>> not make the walls weaker and capable of bearing less weight? On my </FONT>
<BR><FONT SIZE=2>> load-bearing walls I have a clay-tile roof, I donīt know if I could </FONT>
<BR><FONT SIZE=2>> recommend putting a heavy roof on an "uncompressed" loadbearing wall . . </FONT>
<BR><FONT SIZE=2>> .But in the testing people have done they say that the plaster bears more </FONT>
<BR><FONT SIZE=2>> weight than the bales themselves, some maybe my doubts are irrelevant . . </FONT>
<BR><FONT SIZE=2>> .What do you all think?</FONT>
</P>
<P><FONT SIZE=2>I was reflecting the other day about the construction of a Formula 1 car. These </FONT>
<BR><FONT SIZE=2>are made out of thin carbon fibre - the strongest parts of the car are made from </FONT>
<BR><FONT SIZE=2>two thin layers of carbon fibre separated by a weak core material a few mm thick, </FONT>
<BR><FONT SIZE=2>making the whole very much stronger than the sum of the parts. The essential </FONT>
<BR><FONT SIZE=2>element is the gap between the two thin layers - on their own the thin layers will </FONT>
<BR><FONT SIZE=2>bear much less compressive and shearing forces, but as long as a stable gap </FONT>
<BR><FONT SIZE=2>can be maintained between them, their combined strength is very much greater.</FONT>
</P>
<P><FONT SIZE=2>It seems to me that in some respects, this is not so different to a load-bearing SB </FONT>
<BR><FONT SIZE=2>structure - two thin layers of stucco separated by a core of straw. Now carbon </FONT>
<BR><FONT SIZE=2>fibre is much stronger under tension that stucco, but that may not be an issue </FONT>
<BR><FONT SIZE=2>under load-bearing conditions.</FONT>
</P>
<P><FONT SIZE=2>The point is, much evidence suggests that the stucco takes most of the load, </FONT>
<BR><FONT SIZE=2>rather than the straw, so once two layers of stucco are applied, the tendency for </FONT>
<BR><FONT SIZE=2>the straw to settle down may not be as much of a factor as you may first think, </FONT>
<BR><FONT SIZE=2>and the two layers of stucco acting in conjunction with the straw core provides a </FONT>
<BR><FONT SIZE=2>strong enough support.</FONT>
</P>
<P><FONT SIZE=2>I should point out that this is not an expert opinion, just an idea I had.</FONT>
</P>
<P><FONT SIZE=2>-- </FONT>
<BR><FONT SIZE=2>Stewart H.</FONT>
</P>
<P><FONT SIZE=2>____________________________________________________</FONT>
<BR><FONT SIZE=2> European strawbale building discussion list</FONT>
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<P><FONT SIZE=2>Send all messages to:</FONT>
<BR><FONT SIZE=2>Strawbale@amper....muni.cz</FONT>
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