Cob: Cob insulation idea

[Tobin Newburgh]

Darel, I apologize for calling out to you specifically - particularly 
because I am new to this list, maybe it has just been a bad week for you, 
but nearly every email that I have gotten from you through this coblist 
has been very demeaning and negative.  

I am interested in cob and other natural building techniques because I 
seek a sustainable and harmonious alternative to the oppressive and 
destructive path that many of us are currently on.  This for me is much 
greater than simply a science that tells us which materials are best to 
use as to exploit the fewest resources, but it incorporates a philosophy 
to create tolerance and sister/brotherhood amongst all things.  

I appreciate the wealth of information that you've shared with us all 
since I've joined the list, as you certainly have more experience than I 
do.  I do feel that your approach could be modified so that people can 
share things on this list without being shut down.

Myra, I thought that the information you shared was quite interesting - 
thank you.  

Darel, to comment on some of your comments:

> > "Cob, however, is a mediocre insulator with a low R-value per inch.  
> 
> This completely ignores the thermal mass and its effect on heat
> exchange.  Fiberglass companies like to mislead in this way to.  
> Fiberglass damp from condensation or leaks and wind infiltration can
> have even less insulative value than cob.

You too have mentioned that cob doesn't insulate well - although, it's 
true there is little mention of the value of a thermal mass, I don't 
think that's the point.  Nobody here is trying to say that fiberglass is 
better.  The previous link on sprayed foam vs. fiberglass was very 
interesting but completely irrelevant in this case.  If nowhere else, the 
north wall might be more efficient if it is insulated in parts of the 
Pacific Northwest.  

> 
> > On cool days, heat from within bleeds steadily outward.  
> 
>   NOTE 1:  Heat bleeds out from ANY kind of wall if its warmer inside
> than outside.
>   NOTE 2:  Heat does not just bleed out, it goes into the home, if its
> warmer than the inside air.
>   NOTE 3:  It provide a store of heat to keep the inside heat from
> bleeing out so fast.
> 
> 
> > To circuvent this,
> It can't be circumvented.  It can only be reduced for ANY kind of wall
> if there's a temperature difference inside and out.
> 
Maybe circumvent was the wrong word to choose, but heat DOES leak out if 
there is a temp. gradient and this can be further slowed by adding some 
sort of insulation rather than only having a thermal mass with a very low 
insulative value.  

> > City Repair designed a double shell; two six-inch walls of cob 
sepaated by eight
> > inches of insulating straw.
> 
> It would have been better to insulate on the outside and keep the mass
> heat storage inside.
> 
> > On each side of the straw is a wattle wall -
> > flexible sticks woven into a solid barrier-to hold back the cob.
> 
> Hold back the cob?  Cob can stand on its own.  If its waddle and daub,
> then its the bones upon with the daub is glaubed into and onto.  Perhaps
> they required this 8" thin non-bearing walls.
> 
> > This makes for a thick wall, twenty two inches through.
> This can be done with insulation on the outside or with only cob or any
> other material if desired.  Strawbale walls are about this thick after
> being rendered in a soil or lime mortar.
> 
> 
Thank you again for sharing your wisdom, but the author and/or Myra 
weren't wrong in anyway for sharing with us the thickness of the walls, 
they were simply reaffirming the value of having a thick wall whether it 
is for insulative/thermal mass purposes or simply for the aesthetic value.

> > The roof is eually innovative.  Above two-by-six rafters salvaged from
> > shipping palletes lies a polyvinyl chloride (PVC) membrane (PVC 
offers the
> > best protection against leaks buts it manufacture produces toxins.
> 
> I don't get what's innovative about this?  I thought all roofs have a
> waterproof covering.  
> 
I worked as a roofer for 2 years and I do think that this is very 
innovative.  Although living roofs have been around for quite some time 
and have taken many shapes and forms - your average roof holds literally 
tons of mined minerals and petroleum products.  Even the most toxic of 
water barriers in living roofs use significantly fewer materials and 
require less processing.  Other non-petroleum roofs are wood 
shingle/shake and metal roofs.  Wood roofs have become extremely 
unsatisfactory because it is difficult to make one that is long lasting 
without using old growth redwood (which I think is one reason why most of 
us are looking toward alternatives like cob).

> > Other options include liquid asphalt or a rubber membrane.)  Atop 
this is a living
> > roof of sedum and other drought-tolerant plants which can withstand
> > Portland's often dry summers.
> 
> I am convinces that living roofs, a.k.a. green roofs are a very good
> idea.   Does anyone know of any non-toxic materials that can be used for
> the underside as a waterproof barrier?
> 
You'll notice this is the first hint of positivity...  It seems as though 
polyethylene and other lower VOC pond liners are probably some of the 
best at the moment.  PVC is extremely nasty particularly in its 
production - a person who lives in my comunitee has done extensive work 
with PVC production in Thailand and affectionatly refers to PVC piping 
as "cancer in a tube."  The liquid asphalt roofs are just as bad - 
incidentally, the asphalt that is used in Oregon isn't even legal in 
California! There are of course less permanent renewable systems that 
folks are experimenting with (or have been for over 1000 years) such as 
linseed oil soaked canvases (preferably organic hemp or cotton, eh?)
> 
> > Rains trickles trough the greenery, down
> > bamboo gutteres, and into a set of sculptural ponds that hold water 
for the
> > garden.  This reduces pressure on both Portland's water supply and its
> > overtaxed storm-drain system.
> 
> This is Portland's "eco-roof" program.  I wish other cities and states
> would catch onto its benefits.
> 
> Darel
> 

In closing, my understanding when I joined the list was that everyone 
comes to this list with different experiences and wisdoms.  Some things 
shared may seem trivial to others and extremely helpful to others.  
Naturally there will be some people who are very new to the world of cob 
and natural building and it is very much for those people that lists like 
this exist - if only those that knew all the answers were allowed to hear 
those answers then the cob movement wouldn't be able to spread.  Even the 
most experienced designers, builders and hobbyists can learn a great deal 
from this list as well, if they only listen to what others have to say.  
I live in California, but spend a great deal of time in Oregon and am 
very excited to know about this project.  I think that I will contact 
city repair in the near future to further investigate this project and 
others that they are working on.  Only by creating a network of knowledge 
will this movement thrive.  Thank you Myra for sharing.

I am sorry for such a long email, but as Mark Twain said "I didn't have 
the time to write a short one."

Namaste

toby