Cob: RE: Posts embedded in cob
Firstbrook, Will
wfirstb1 at wcb.bc.ca
Wed Nov 1 19:28:19 CST 2000
Hi Robynn,
The answer to your questions are "it depends" on the details. I helped build
in a cob workshop a cob structure that was post & beamed code approved.
Although the posts are visible on the outside. If interested you can
checkout the following pictures on my website
http://www.geocities.com/RainForest/Canopy/7148/cobpics.html
<http://www.geocities.com/RainForest/Canopy/7148/cobpics.html>
The 3rd & 4th picture from the end. Or specifically:
http://www.geocities.com/RainForest/Canopy/7148/ma4.jpg
<http://www.geocities.com/RainForest/Canopy/7148/ma4.jpg> &
http://www.geocities.com/RainForest/Canopy/7148/ma3.jpg
<http://www.geocities.com/RainForest/Canopy/7148/ma3.jpg> .
You can check out http://www.life.ca/nl/74/straw.html
<http://www.life.ca/nl/74/straw.html> for more details about straw-clay.
It is good to have nails or pegs in the posts to key-in the wall (regardless
if it is cob, straw-clay or strawbale). Yes you can cob over the posts.
Although if it is not a thick layer you might want to cover the wood with
tar paper and some screening material to minimize cracking as the wood can
dry out the cob or plaster too fast compared to the rest of the wall. You
can use galvanized stucco wire screening on both sides of the will prior to
cobbing or plastering the wall. This will strengthen the wall and reduce any
chance of the wall falling over.
Any bug problem can be addressed by the finishing plasters. Cob, Straw-clay
& strawbale all have one common weakness water/moisture. This must be
addressed by the foundation design and materials and sufficient roof
overhangs. The stories you have heard about strawbale failures are all
related to excess moisture, water getting into the wall and not getting out
fast enough, rot & insects occur when there is 20% or more moisture in the
wall, measured by weight.
I am currently building a modified post & beam strawbale house in the BC
interior. It lived through 2 winters with raw bales exposed inside and out.
Our family of five lived in it through last winter there is no rot & no
bugs. After driving rain I have checked the bales, they are dry as I have
sufficient overhang. It all depends on the details. I have a metal roof and
a large foundation, The bales are actually 5 feet off the ground and lifted
2" off the floor so any plumbing water leak wont touch the bales. I am using
a sand, lime, clay, straw plaster to allow the bales to breathe. Trapped
water is the cause of most rot.
Regards,
Will
-----Original Message-----
From: Shawn Honeychurch [ mailto:ironfire at cyberlink.bc.ca
<mailto:ironfire at cyberlink.bc.ca> ]
Sent: Wednesday, November 01, 2000 4:03 AM
To: Firstbrook, Will; coblist at deatech.com <mailto:coblist at deatech.com>
Subject: Re: Posts embedded in cob
Hi Will
Thanks for your thoughts. We really want to go with the post and beam
design, because it will be easier for us to get a building permit. With
your staw-clay idea, how dense would you pack it into the forms, do you
think? And could we still cob over the posts? Would cob on a straight
straw-clay be any stronger than a straight cob wall? I worry about it
wanting to fall over, being lighter weight and all. The idea of building
faster and improved insulation value with this method is, of course,
appealing, but do you think there is a greater risk of having bug problems
in a straw-clay wall than a cob wall?
I am not inclined to building with straw bales as I have heard too many
stories of problems with bugs and rot. Am I being paranoid as we live in a
semi-arid climate here?
Thanks for your input.
Robynn
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<TITLE>RE: Posts embedded in cob</TITLE>
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<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial size=2>Hi
Robynn,</FONT></SPAN></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial size=2>The
answer to your questions are "it depends" on the details. I helped
build in a cob workshop a cob structure that was post & beamed code
approved. Although the posts are visible on the outside. If interested you
can checkout the following pictures on my website </FONT></SPAN></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN><FONT color=#0000ff size=2><A
href="http://www.geocities.com/RainForest/Canopy/7148/cobpics.html">http://www.geocities.com/RainForest/Canopy/7148/cobpics.html</A></FONT></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial size=2>The
3rd & 4th picture from the end. Or specifically:
<DIV> </DIV>
<DIV><A
href="http://www.geocities.com/RainForest/Canopy/7148/ma4.jpg">http://www.geocities.com/RainForest/Canopy/7148/ma4.jpg</A>
&</FONT></SPAN></DIV></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN><FONT color=#0000ff size=2><A
href="http://www.geocities.com/RainForest/Canopy/7148/ma3.jpg">http://www.geocities.com/RainForest/Canopy/7148/ma3.jpg<SPAN
class=940300600-02112000><FONT color=#800080 face=Arial size=2>.</A>
</FONT></SPAN></FONT></DIV>
<DIV><FONT color=#0000ff size=2><SPAN class=940300600-02112000><FONT
color=#800080 face=Arial size=2></FONT></SPAN></FONT><SPAN
class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial size=2>You
can check out <A
href="http://www.life.ca/nl/74/straw.html">http://www.life.ca/nl/74/straw.html</A>
for more details about straw-clay. It is good to have nails or pegs in the posts
to key-in the wall (regardless if it is cob, straw-clay or strawbale). Yes you
can cob over the posts. Although if it is not a thick layer you might want to
cover the wood with tar paper and some screening material to minimize cracking
as the wood can dry out the cob or plaster too fast compared to the rest of the
wall. You can use galvanized stucco wire screening on both sides of the
will prior to cobbing or plastering the wall. This will strengthen the wall and
reduce any chance of the wall falling over. </FONT></SPAN></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial size=2>Any
bug problem can be addressed by the finishing plasters. Cob, Straw-clay &
strawbale all have one common weakness water/moisture. This must be addressed by
the foundation design and materials and sufficient roof overhangs. The stories
you have heard about strawbale failures are all related to excess moisture,
water getting into the wall and not getting out fast enough, rot & insects
occur when there is 20% or more moisture in the wall, measured by weight.
</FONT></SPAN></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial size=2>I am
currently building a modified post & beam strawbale house in the BC
interior. It lived through 2 winters with raw bales exposed inside and out. Our
family of five lived in it through last winter there is no rot & no bugs.
After driving rain I have checked the bales, they are dry as I have sufficient
overhang. It all depends on the details. I have a metal roof and a large
foundation, The bales are actually 5 feet off the ground and lifted 2" off
the floor so any plumbing water leak wont touch the bales. I am using a sand,
lime, clay, straw plaster to allow the bales to breathe. Trapped water is the
cause of most rot.</FONT></SPAN></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2>Regards,</FONT></SPAN></DIV>
<DIV><SPAN class=940300600-02112000><FONT color=#0000ff face=Arial
size=2>Will</FONT></SPAN></DIV>
<DIV> </DIV>
<BLOCKQUOTE>
<DIV class=OutlookMessageHeader><FONT face="Times New Roman"
size=2>-----Original Message-----<BR><B>From:</B> Shawn Honeychurch [<A
href="mailto:ironfire at cyberlink.bc.ca">mailto:ironfire at cyberlink.bc.ca</A>]<BR><B>Sent:</B>
Wednesday, November 01, 2000 4:03 AM<BR><B>To:</B> Firstbrook, Will; <A
href="mailto:coblist at deatech.com">coblist at deatech.com</A><BR><B>Subject:</B>
Re: Posts embedded in cob<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>Hi Will</FONT></DIV>
<DIV><FONT face=Arial size=2>Thanks for your thoughts. We really want
to go with the post and beam design, because it will be easier for us to get
a building permit. With your staw-clay idea, how dense would you pack
it into the forms, do you think? And could we still cob over the
posts? Would cob on a straight straw-clay be any stronger than a
straight cob wall? I worry about it wanting to fall over, being
lighter weight and all. The idea of building faster and improved
insulation value with this method is, of course, appealing, but do you think
there is a greater risk of having bug problems in a straw-clay wall than a
cob wall? </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>I am not inclined to building with straw bales
as I have heard too many stories of problems with bugs and rot. Am I
being paranoid as we live in a semi-arid climate here?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Thanks for your input.</FONT></DIV>
<DIV><FONT face=Arial size=2>Robynn</FONT></DIV>
<DIV> </DIV>
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