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<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'>Hi,<br>
The English (UK) solution to this not uncommon situation would be to insulate
above the floor, leaving the timber to age in a ventilated space, which will
protect it from damp build up.<br>
<br>
John Bone, MBEng, BSc Hons<br>
UK Building Code Official (1974-2009)<br>
UK Fire Risk Assessor (2009-ongoing)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:blue'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span lang=EN-US
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span lang=EN-US style='font-size:10.0pt;font-family:Tahoma'>
greenbuilding-bounces@lists.bioenergylists.org
[mailto:greenbuilding-bounces@lists.bioenergylists.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b>elitalking<br>
<b><span style='font-weight:bold'>Sent:</span></b> 11 April 2012 16:14<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on"><st1:place
w:st="on"><st1:PlaceName w:st="on">Green</st1:PlaceName> <st1:PlaceType w:st="on">Building</st1:PlaceType></st1:place></st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> [Greenbuilding]
Insulating shallow crawl spaces</span></font><span lang=EN-US><o:p></o:p></span></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>I have a deep energy retrofit project on an old framed house where
there was no excavation for the crawls space. The result is that the
front, downhill side of the house has adequate room for installing
insulation. However, much of the house has less
(18”-24”). The floor condition is good enough that we are not
considering removing the floor. The room height is insufficient to
consider adding insulation to the top of the floor. How do I insulate the
floor. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>For the rest of the house, we are planning on installing new ceiling
rafters parallel to the roof pitch to define 14” space to fill with open
cell foam. We are installing furring strips installed with 2” gap
in front of old wood siding. We are adding continuous 2.5” closed
cell foam to fill the gap. The old plaster is gutted. We can fill
with adhered cellulose or open cell foam in the 2x4 framed walls. On
another similar job, I came to the inside of the foundation to continue closed cell
foam thermal barrier and came across the ground with closed cell foam.
All of that was covered with the high cost spray ignition barrier. In
hind site, with that job, I would have preferred to use rigid board insulation
such as XPS. I would create a ground plane with combination of digging
high spots and filling low spots with crush and run (small gravel), lay one
layer of extruded board to provide puncture protection, a layer of poly for
continuous vapor barrier and another foam layer. I put osb on top for
cheap ignition barrier that protects the foam from traffic damage. The
whole house is provided with HRV for fresh air. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>However, this house does not have adequate space to work in. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>Do I need to hand excavate to a minimum clearance for the work? If we
did that, I could install either of the approaches describe above.
I was wondering if I could fill the whole space with open cell foam. I
realize that 1/2 # open cell foam is not a vapor barrier, therefore likely not
a good idea. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>I am encouraging my client to use a mini split heat pump to avoid the
need for ductwork in the crawl space. Therefore, I can define the thermal
barrier at the floor plane instead of the ground. Because we would still
have moisture issues below, I am leaning towards ground insulation. However,
a closed cell foam application to the bottom of the framing could provide the
vapor barrier to protect the wood. Below that the stone and concrete
surfaces are not vulnerable to humidity. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>Right now, I consider the hand excavation to be the most likely
scenario. Because the mini split will cool the house, I am against the
traditional ventilated crawl spaces with fiberglass batts in floor framing
because the cool shadow will pull in hot humid air and cool it to dew point
creating humidity problems. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>This is a common situation with old house. I hope our list can
offer some good ideas for cost affective ways of upgrading to a high
standard. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'>Eli <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=5 face="Times New Roman"><span style='font-size:
16.0pt'><a href="http://www.conservationarchitect.net/">www.conservationarchitect.net</a><o:p></o:p></span></font></p>
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