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

[Monica Proulx]

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.