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    <div class="moz-cite-prefix">In the ASTM tests that Bruce King
      coordinated back in 2007, one of the walls was clay plastered. <br>
      <br>
      Yes, the clay cracked and the straw eventually burned (though the
      clay plastered wall did better than cement, we believe because it
      spent the first 20 min or so "firing" as in a kiln, and the
      chemical changes from that absorbed a lot of the heat).  <br>
      <br>
      Loosely packed straw might not fare so well once oxygen can get to
      it.  <br>
      <br>
      We had a problem because the clay plastered wall had a crack on
      the exterior, which allowed more oxygen in between a couple
      bales.  Though we had stuffed and cobbed those spaces maniacally,
      the fire followed the path back through the wall.  We had to cut
      the test off at 1 hour because of this - otherwise the clay
      plastered wall probably would have out-performed the cement
      plastered one. <br>
      <br>
      The guys at the testing facility told us that "Everything burns...
      eventually.   Everything". <br>
      <br>
      I have to agree with the earlier comments in this thread - loose
      straw as ceiling insulation is just asking for problems, whether
      hit with clay slip or not.  <br>
      <br>
      On 10/25/17 4:56 PM, Bohdan Dorniak wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:005501d34ddc$274ba890$75e2f9b0$@bdcoarchitects.com.au">
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        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi
            All<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Graeme
            – I’d be worried about your statement about a “coating of
            clay” – in our fire test of rendered strawbales by CSIRO -
            done in 2002 – the earth rendered bale (render about 50mm
            thick – Frank Thomas did the rendering) started to show
            cracking in the render.<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Wondering
            whether eventually they would burn? <o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Other
            considerations is the weight factor and stronger ceiling
            structures (if using thicker coats of render).<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">That’s
            my 2 bob’s worth.<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Bohdan<o:p></o:p></span></p>
        <p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
        <p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""
              lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""
            lang="EN-US"> Gsbn
            [<a class="moz-txt-link-freetext" href="mailto:gsbn-bounces@sustainablesources.com">mailto:gsbn-bounces@sustainablesources.com</a>] <b>On Behalf
              Of </b>Misha Rauchwerger<br>
            <b>Sent:</b> Thursday, 26 October 2017 8:04 AM<br>
            <b>To:</b> Global Straw Building Network<br>
            <b>Subject:</b> Re: [GSBN] using loose straw insulation in
            roof<o:p></o:p></span></p>
        <p class="MsoNormal"><o:p> </o:p></p>
        <div>
          <p class="MsoNormal">I believe another issue is whether the
            attic space is vented or not, as well as the kind of
            roofing.  After the Oakland fires, I remember this being
            debated furiously, because the codes require attic venting,
            and going with something like polyisocyanurate rigid
            insulation without vents was controversial.  Obviously the
            fire danger will increase if air can mix with flammable
            insulation fuel (frieze block vents and ridge vents create a
            perfect means for fully combusting the attic materials) . If
            it is encased and covered with earth on the outside and
            inside (plaster on the ceiling), as in a living roof, we can
            decrease the flammability factor.<o:p></o:p></p>
          <div>
            <p class="MsoNormal"><o:p> </o:p></p>
          </div>
          <div>
            <p class="MsoNormal">The Lobo fire that swept through our
              neighborhood recently came right to our friend's straw
              bale house with only superficial plaster damage on one
              corner.  Of course there are far too many factors to say
              it was saved because of being straw bale or not.<o:p></o:p></p>
            <div>
              <p class="MsoNormal"><o:p> </o:p></p>
            </div>
            <div>
              <p class="MsoNormal">Then again, if you get a fire like
                just swept through Napa and Sonoma Counties, all bets
                are off...<o:p></o:p></p>
            </div>
            <div>
              <p class="MsoNormal"><o:p> </o:p></p>
            </div>
            <div>
              <p class="MsoNormal">Misha <o:p></o:p></p>
            </div>
          </div>
        </div>
        <div>
          <p class="MsoNormal"><o:p> </o:p></p>
          <div>
            <p class="MsoNormal">On Wed, Oct 25, 2017 at 1:38 PM, Graeme
              North <<a href="mailto:graeme@ecodesign.co.nz"
                target="_blank" moz-do-not-send="true">graeme@ecodesign.co.nz</a>>
              wrote:<o:p></o:p></p>
            <div>
              <p class="MsoNormal">This list is a fantastic resource for
                learned info and is greatly appreciated I can tell you.<o:p></o:p></p>
              <div>
                <p class="MsoNormal"><o:p> </o:p></p>
                <div>
                  <p class="MsoNormal">The fire thing is scary - there
                    is no requirement in NZ for single dwellings to have
                    fire resistant ceiling materials, but we do need to
                    have smoke alarms near bedrooms and escape routes.<o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal">The really scary thing is that
                    the fire people here advise that a dry house with an
                    open attic with light timber rafters or trusses for
                    roof framing will burn from end to end in 60 secs.<o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal">Goodness knows what adding an
                    accelerant like straw (without a good clay coating)
                    might do. I would advise against it.<o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal"><o:p> </o:p></p>
                </div>
                <div>
                  <p class="MsoNormal">I would use straw coated with
                    clay  - pretty much a LEM mix - if my structure
                    allowed it to happen easily and I was considering it
                    for my own house but the work required and extra
                    weight decided against it <o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal">and again recently I considered
                    it on another design but the considerably increased
                    extra depth of the roof structure to accommodate it,
                    along with the extra cost, work, and weight, decided
                    against it again so I went with wool insulation in
                    both cases.<o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal"><o:p> </o:p></p>
                </div>
                <div>
                  <p class="MsoNormal">I am also not convinced that
                    cellulose/paper insulation with borax retains it
                    fire rating over time - I have seen examples of old
                    (only a few years) cellulose insulation that would
                    not ignite when new,  ignite readily with a match
                    and it seems to keep burning quite happily.<o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal"><o:p> </o:p></p>
                </div>
                <div>
                  <p class="MsoNormal"><o:p> </o:p></p>
                </div>
                <div>
                  <p class="MsoNormal">Cheers<o:p></o:p></p>
                </div>
                <div>
                  <p class="MsoNormal"><span style="color:#888888"><o:p> </o:p></span></p>
                </div>
                <div>
                  <p class="MsoNormal"><span style="color:#888888">Graeme<o:p></o:p></span></p>
                </div>
                <div>
                  <div>
                    <div>
                      <p class="MsoNormal">     <o:p></o:p></p>
                    </div>
                    <div>
                      <p class="MsoNormal"><o:p> </o:p></p>
                    </div>
                    <div>
                      <p class="MsoNormal"><o:p> </o:p></p>
                    </div>
                    <div>
                      <p class="MsoNormal"><o:p> </o:p></p>
                    </div>
                    <div>
                      <p class="MsoNormal"><o:p> </o:p></p>
                    </div>
                    <div>
                      <p class="MsoNormal"><o:p> </o:p></p>
                    </div>
                    <div>
                      <p class="MsoNormal"><o:p> </o:p></p>
                      <div>
                        <blockquote
                          style="margin-top:5.0pt;margin-bottom:5.0pt">
                          <div>
                            <p class="MsoNormal">On 26/10/2017, at 5:36
                              AM, Bruce EBNet <<a
                                href="mailto:bruce@ecobuildnetwork.org"
                                target="_blank" moz-do-not-send="true">bruce@ecobuildnetwork.org</a>>
                              wrote:<o:p></o:p></p>
                          </div>
                          <p class="MsoNormal"><o:p> </o:p></p>
                          <div>
                            <div>
                              <div>
                                <p class="MsoNormal"><o:p> </o:p></p>
                              </div>
                              <p class="MsoNormal">Don’t you love it
                                when someone else chimes into these
                                discussions ahead of you, and says
                                everything you wanted to say?  <o:p></o:p></p>
                              <div>
                                <p class="MsoNormal"><o:p> </o:p></p>
                              </div>
                              <div>
                                <p class="MsoNormal">I sure do.  Thank
                                  you Derek and John;  what they said.<o:p></o:p></p>
                              </div>
                              <div>
                                <p class="MsoNormal"><o:p> </o:p></p>
                                <div>
                                  <div>
                                    <div>
                                      <div>
                                        <p class="MsoNormal">Bruce King<o:p></o:p></p>
                                      </div>
                                      <div>
                                        <p class="MsoNormal"><a
                                            href="tel:%28415%29%20987-7271"
                                            target="_blank"
                                            moz-do-not-send="true">(415)
                                            987-7271</a><o:p></o:p></p>
                                      </div>
                                      <div>
                                        <p class="MsoNormal"><a
                                            href="mailto:bruce@ecobuildnetwork.org"
                                            target="_blank"
                                            moz-do-not-send="true">bruce@ecobuildnetwork.org</a><o:p></o:p></p>
                                      </div>
                                      <div>
                                        <p class="MsoNormal"><o:p> </o:p></p>
                                      </div>
                                    </div>
                                    <div>
                                      <p class="MsoNormal"><o:p> </o:p></p>
                                    </div>
                                  </div>
                                  <p class="MsoNormal"
                                    style="margin-bottom:12.0pt"><o:p> </o:p></p>
                                </div>
                                <p class="MsoNormal"><o:p> </o:p></p>
                                <div>
                                  <blockquote
                                    style="margin-top:5.0pt;margin-bottom:5.0pt">
                                    <div>
                                      <p class="MsoNormal">On Oct 25,
                                        2017, at 7:56 AM, John Straube
                                        <<a
                                          href="mailto:jfstraube@uwaterloo.ca"
                                          target="_blank"
                                          moz-do-not-send="true">jfstraube@uwaterloo.ca</a>>
                                        wrote:<o:p></o:p></p>
                                    </div>
                                    <p class="MsoNormal"><o:p> </o:p></p>
                                    <div>
                                      <p class="MsoNormal">I would echo
                                        Derek’s concerns exactly. Loose
                                        fluffy straw burns very quickly
                                        and you may as well say you lost
                                        the house.<br>
                                        Adding clay slips will increase
                                        the fire resistance to the point
                                        is acceptable, as will dense
                                        bales with some sort of clay
                                        slip top, but once you do that,
                                        you have a heavy and labor
                                        intensive roof insulation.<br>
                                        Cellulose with 20%+ borate
                                        treatment is inexpensive, gives
                                        good R-value, is widely
                                        available, and is very good at
                                        fire resistance.<br>
                                        <br>
                                        <br>
                                        <o:p></o:p></p>
                                      <p class="MsoNormal">On Oct 25,
                                        2017, at 10:00 AM, Derek Roff
                                        <<a
                                          href="mailto:derek@unm.edu"
                                          target="_blank"
                                          moz-do-not-send="true">derek@unm.edu</a>>
                                        wrote:<br>
                                        <br>
                                        I have a different concern about
                                        using straw packed at
                                        low-densities in the roof.  I
                                        think that the fire risk
                                        increase is much more of a
                                        problem than the decrease in
                                        insulation value.  If you have
                                        seen flakes of straw or loose
                                        straw burn, you will be aware
                                        that they are much more
                                        flammable than standard bales. 
                                        Straw flakes are probably about
                                        half the density of a building
                                        bale, and loose straw might cut
                                        the density in half again.  <br>
                                        <br>
                                        Losing the roof in a fire
                                        usually means losing the whole
                                        house’s integrity and value. 
                                        While enclosing the flakes or
                                        loose straw for the roof in
                                        plywood, for example, would help
                                        somewhat with fire resistance, I
                                        recommend against design choices
                                        that depend on a few things
                                        going right to avoid a
                                        catastrophic failure in a fire.
                                         <br>
                                        <br>
                                        An additional consideration that
                                        has been mentioned here before,
                                        is that while bales may be
                                        relatively inexpensive, placing
                                        them in the roof requires
                                        increasing the size and number
                                        of the roof’s structural
                                        elements, which will likely
                                        raise costs more than the amount
                                        saved by using bales instead of
                                        other insulation materials in
                                        the roof.  Using lower density
                                        straw diminishes that problem to
                                        some extent, but straw is still
                                        likely to be significantly
                                        heavier than other kinds of roof
                                        insulation, for an equivalent
                                        insulation value.  <br>
                                        <br>
                                        Derek<br>
                                        <br>
                                        Derek Roff<br>
                                        <a href="mailto:derek@unm.edu"
                                          target="_blank"
                                          moz-do-not-send="true">derek@unm.edu</a><br>
                                        <br>
                                        <br>
                                        <br>
                                        <br>
                                        <br>
                                        <o:p></o:p></p>
                                      <p class="MsoNormal">On Oct 25,
                                        2017, at 4:34 AM, Rikki Nitzkin
                                        <<a
                                          href="mailto:rikkinitzkin@gmail.com"
                                          target="_blank"
                                          moz-do-not-send="true">rikkinitzkin@gmail.com</a>>
                                        wrote:<br>
                                        <br>
                                        Hi!<br>
                                        <br>
                                        I don’t know if you all
                                        remember, but not long ago I
                                        asked about the MAXIMUM density
                                        of a SB before it begins loosing
                                        thermal properties… most people
                                        agreed that we should not worry
                                        about a bale being too dense.<br>
                                        <br>
                                        Now I ask about the opposite
                                        question: is there a minimum
                                        density?<br>
                                        <br>
                                        The other day we were talking
                                        about using flakes of straw to
                                        insulate a roof. One of the
                                        builders insisted that is was
                                        important that the insulation
                                        cavity was filled with highly
                                        compressed straw, and another
                                        said that as long as the cavity
                                        was properly filled (leaving no
                                        big holes for air to circulate)
                                        that the density of the infill
                                        is not important, as the straw
                                        (loose or dense, but enclosed in
                                        the insulation cavity) impedes
                                        the circulation of air, and that
                                        is what insulates.<br>
                                        <br>
                                        Can any of you technicians refer
                                        me to studies about insulation
                                        properties and how they relate
                                        to density? or at least clarify
                                        my doubt: Is it important to
                                        highly compact the insulation in
                                        the roof? and why… so I can
                                        explain it better.<br>
                                        <br>
                                        thanks!<br>
                                        Rikki<o:p></o:p></p>
                                      <p class="MsoNormal"><br>
                                        ______</p>
                                    </div>
                                  </blockquote>
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                        </blockquote>
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                    </div>
                  </div>
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      </div>
    </blockquote>
    <br>
    <pre class="moz-signature" cols="72">-- 
Bill Christensen
<a class="moz-txt-link-freetext" href="http://SustainableSources.com">http://SustainableSources.com</a>
<a class="moz-txt-link-freetext" href="http://LinkedIn.com/in/billc108">http://LinkedIn.com/in/billc108</a></pre>
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