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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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</div>
</blockquote>
</div>
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</div>
</div>
</div>
</div>
</div>
</div>
</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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