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Hi Alfred,<br>
<br>
The creation of bale buildings that address infiltration has been my
main focus for the past few years of design/build, and we've got it
down pretty well now. Our last blower door test had 1.2 ACH/50, and
afterwards we realized that the plumbing stack was open! So the
walls and wall junctions were really tight. The house we did for
Habitat for Humanity last year
<a class="moz-txt-link-freetext" href="http://endeavourcentre.com/our-portfolio/habitat-for-humanity-house/">http://endeavourcentre.com/our-portfolio/habitat-for-humanity-house/</a>
had some issues around the straw/clay walls we did, but the bale
walls were tight and the house ended up at 2.1 ACH/50.<br>
<br>
In particular, I've been focusing on how to achieve this level of
air tightness without lots of yucky "product." For the bale walls,
here's what we do:<br>
<br>
- a strip of air barrier runs along the top edge of the wall,
running along the bales, under a strip of mesh, so that the barrier
is covered by the plaster and ties into the barrier in the ceiling.
This is the biggest leaky place in most bale buildings.<br>
- depending on the floor/foundation type, we'll use a similar
strategy at the bottom of the wall for wooden floor systems or good
sill gasketing and a caulk line on the interior and exterior edges
for slabs.<br>
- at windows, we don't use spray foam but a light mix of hempcrete
to seal around the windows. Barrier strips are used here too under
the plaster seam.<br>
- electrical outlets get site-made barrier "hats" and we caulk
around the wire once it's been put through the barrier. We've also
used the plastic "R-2000" electrical boxes but we don't trust the
neoprene seal for the wire and caulk these too.<br>
<br>
It's really pretty darn easy to get a bale wall air tight. The
beauty of the continuous plaster is that there aren't that many
seams, and the ones that do exist are easy to predict and do
something about! It's a much less difficult and troublesome process
than making a frame house air tight.<br>
<br>
As a side note, the prefab panels we've been making have these
barrier "tails" already embedded and ready for joining to other
building elements.<br>
<br>
The insulation value question is about to come and haunt us in
Ontario too. In January, the codes here raise the required R-values
and I'm sure we'll be facing some questions from plans reviewers who
use the lowest possible figures that are out there. I'm hoping that
we can set up some full-scale testing here to get good figures on a
full wall panel, and of course we'll share any results we get.<br>
<br>
Chris "Starving for Air" Magwood<br>
<br>
On 11-10-03 11:49 AM, Alfred von Bachmayr wrote:
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<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">Greetings
all,<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">Thank
you for
including me in this elite group of building
scholars. <o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">I
wanted to get
feedback on some performance aspects of
strawbale building that I have been
confronted with by energy modeling and
regulatory entities that question its thermal
performance. This resistance appeared when I
contracted a Hers rater
along with mechanical engineers who, in
generating thermal models of a strawbale
building I had designed, consistently gave it
low ratings for R-value and
infiltration. In researching the R-value they
had given to the walls, I found
that from the resources they had found, the
value was somewhere between R-23
and R-27. I got a copy of the newly proposed
International Green
Conservation Code and found they rated bales
laid flat at R-1.3 per inch and on
edge R-2. That equates to R-23.4 for flat
bales (2 string) and R-28 for
bales (2-string) on edge. I don’t think this
gives and accurate
performance prediction of the building. In
addition they considered
the buildings to have high infiltration losses
because of their opinion that
they cannot be tightly sealed. Their models
indicated that the building
could not be considered high performance due
to the use of the straw thereby
making my job of getting the building to the
required Hers rating value much
more difficult. I am thinking I am not alone
in this problem.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">This
made me realize
that we need to generate more convincing
documentation as to the performance
and design detailing of straw buildings.
There appears to be little
resources out there that engineering
professionals access that address the
infiltration and insulation values of straw.
This is important because without
a sufficient HERS rating and a positive blower
door test (now being required in
many jurisdictions) a permit and/or a CO will
not be issued.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">What
I would like to
hear from you all is the location of resources
documenting tight houses out of
straw (like the passive houses) and specific
techniques you have used to tightly
seal up straw buildings. Specifically what
techniques have you used to seal
around the windows and doors, at the bottom
and top of the walls and at penetrations
of the interior finish skins for electrical
boxes. Are there buildings
out there that have gotten their HHI ratings
down below 2 BTU/SF/DD? If
so what techniques did they use and what
insulation and infiltration rates were
used? <o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">Thank
you for your
help.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">Saludos,<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon">Alfred<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="maroon"><span
style="font-size:11.0pt;font-family:Georgia;color:maroon"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="teal"><span style="font-size:
10.0pt;font-family:Georgia;color:teal">VON
BACHMAYR ARCHITECTS LLC</span></font><font
color="maroon"><span style="color:maroon"><o:p></o:p></span></font></p>
<p class="MsoNormal"><st1:street w:st="on"><st1:address
w:st="on"><font face="Georgia" size="2"
color="teal"><span
style="font-size:10.0pt;font-family:Georgia;
color:teal">1406 Bishops Lodge Rd.</span></font></st1:address></st1:street><font
color="maroon"><span style="color:maroon"><o:p></o:p></span></font></p>
<p class="MsoNormal"><st1:place w:st="on"><st1:city
w:st="on"><font face="Georgia" size="2"
color="teal"><span
style="font-size:10.0pt;font-family:Georgia;
color:teal">Santa Fe</span></font></st1:city><font
face="Georgia" size="2" color="teal"><span
style="font-size:10.0pt;font-family:Georgia;color:teal">,
<st1:state w:st="on">NM</st1:state> <st1:postalcode
w:st="on">87506</st1:postalcode></span></font></st1:place><font
color="maroon"><span style="color:maroon"><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Times New Roman"
size="3" color="maroon"><span
style="font-size:12.0pt;color:maroon"> <o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="#008040"><span
style="font-size:10.0pt;font-family:Georgia;color:#008040">505-989-7000
</span></font><font color="maroon"><span
style="color:maroon"><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="#008040"><span
style="font-size:10.0pt;font-family:Georgia;color:#008040">505-984-1479
fax</span></font><font color="maroon"><span
style="color:maroon"><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="#008040"><span
style="font-size:10.0pt;font-family:Georgia;color:#008040">505-470-6141
mobile</span></font><font color="maroon"><span
style="color:maroon"><o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Times New Roman"
size="3" color="maroon"><span
style="font-size:12.0pt;color:maroon"> <o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Georgia" size="2"
color="#008040"><span
style="font-size:10.0pt;font-family:Georgia;color:#008040"><a class="moz-txt-link-abbreviated" href="mailto:vbarch@comcast.net">vbarch@comcast.net</a></span></font><o:p></o:p></p>
<p class="MsoNormal"><font face="Times New Roman"
size="3"><span style="font-size:
12.0pt"><o:p> </o:p></span></font></p>
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