[Cob] Sky's ideas on embodied energy/building materials, cob and light straw clay hybrid

[Jill Hogan]

I have wondered about building two wattle and daub walls and ramming 
light straw clay between them like rammed earth but with softer organic 
walls than the straightness of rammed earth, and the straw would be 
wonderful insulation between the two walls. And you could use local wood 
from local forests and cut down on the manufacturing and transporting 
processes.
Love wattle and daub one of the oldest, quickest and simplest methods of 
building. I have a shipping container I bought 16 years ago when I 
started my project and have used it for storage, workshop etc, but gets 
very hot and very cold so am going to try putting up a wattle and daub 
wall around it and rammming the light straw clay between the wall and 
container. I cobbed the top of the container as it was leaking and have 
lime rendered the roof and it has halved the temp and no more leaking roof

Jill Hogan

On 2011/11/13 12:48 AM, Monica Proulx wrote:
> I enjoyed reading about/seeing pics of Sky's cob and cord wood addition.  I
> get excited when people work on refining energy efficient building methods
> that include cob and light clay straw.  So this looks like a good time to
> pitch the idea of a light clay straw insulation layer on a cob structure
> again!!  I know some people have done this, I'd love for them to post their
> experience on the coblist.
>
> Sky's point a few coblists back - on how energy-efficient stick-built
> houses save on wood and energy in the long run - got me cogitating on this
> topic (cob-LSC hybrid) again.  He said:
>
>
>> .....over a house's lifetime, energy savings adds up--much more so than
>> embodied energy in materials.
>>
>> A mis-designed house, even a small one, will burn a lot of fuel to heat
>> itself, and if its a woodstove, will burn
>>   a lot more wood than it would take to build a Larsen truss house. You
>> could easily burn that much wood in only one winter!
>>
> *
> Designing a system to wrap a cob house in Light Straw Clay *
> I'm determined to design a workable anchor system one would build-in (cob
> in) a wall so that you can later attach form boards for back-filling with a
> LSC layer that will stay attached and stable.  Retrofitting an existing cob
> building with LCS is another challenge I want to look at later.  This outer
> LSC layer may not be suitable for every climate, but with a deep roof
> overhang, good foundation and a sturdy lime plaster on the outside, it
> could work well in places without long monsoon seasons.
>
> To that end I have been designing and revising (on paper only) a minimal
> sized wooden anchor one could bury (multiples of) in a cob wall.  These
> anchors need to be small enough to not interfere with the cob wall
> integrity, and sturdy enough to attach an outside anchor system to. The
> exterior anchor system in turn would support a light weight (temporary)
> vertical framework (12 inch form boards) that would hold LSC material til
> it dries.  I think I've figured out how to cut the interior and exterior
> anchors (different sizes) tessellation style (= minimal waste), out of 12
> inch boards.  Anyone interested in sketches, email me.  (to the young
> couple that emailed me before, I've made changes, I think I've lost your
> contact info.)
> *
> The whole-energy equation*
> When deciding how to build for each persons specific needs, I really think
> keeping the whole long-term energy equation in mind (the embodied energy of
> building materials vs. the amount of energy to heat to the occupants
> desire), is essential if one is interested in the environment and making
> oil supplies last.  I liked the point made recently on coblist (sorry,
> can't remember who) about being willing to tolerate less than ideal inside
> temperatures.  That, along with the willingness to live small are both
> possible factors in the whole-energy equation also.  Making "sacrifices"
> (size, comfy temps) isn't for everyone, but that's ok.  There are about
> 664,000 homeless people in the U.S. alone (not to mention the world), for
> whom those constraints would be a step-up from what they live every day.
> There is value in working on a cob LSC hybrid system for the homeless
> population alone.  (google Destiny Village, Portland, OR, thanks to coblist
> moderator for that tip).  Just seeing how many homeless folks have inserted
> themselves into the "Occupy" encampments recently for access to tents, food
> and medical care, has brought this point home to me hard.
>
> If anyone in Utah or Idaho is interested in doing something small and
> experimental along these lines, I will make some long weekends available
> this spring/summer, plus vacation time I'd sacrifice, in which to travel to
> your land and help out (might be able to bring a 21 year old son along who
> has some timber framing experience and lots of natural plaster expertise).
> I'm thinking this needs to be within a half day's drive from central Utah
> though.
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-- 
*Jill Hogan*
McGregor Alternative Technology Centre "MAT"
PO Box 365
McGregor
6708

www.mat.org.za <http://www.mat.org.za>
Phone: 023 625 1533

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"Be the change you wish to see" Mohandas Ghandi

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