Cob: RE: Cob-Strawbale Hybrid.

[Michael Saunby]

On 20 August 1999 17:35, Tony Glaser [SMTP:aglaser at engsoc.carleton.ca] 
wrote:
> > I'm inclined to include strawbale insulation all 'round the house...
> > It also occurs to me that it may be possible to build somewhat higher
> > "lifts" of cob in this technique - the strawbales would act as one side 
of a
> > form, and may give enough added some support to the mix to prevent 
slumping
> > 'till the courses were a few inches higher.  Sticking some bamboo 
stakes
> > etc. through the strawbales into the cob on each side may also prevent 
bale
> > settling -- both sides of the bales would effectively be held in place 
by a
> > masonry wall.
>
> I don't understand this last part. I think I can figure out what courses
> and slumping are, but why does getting 'a few inches higher' fix 
slumping.
> If slumping is what I think it is, it's prevented by keeping the top of
> the course level, no? What's height got to do with it?  I can figure out
> what bale settling is.
>

Courses - like brick or block laying, you do one course, i.e. layer at a 
time.  Wet cob is "plastic" so you can't put an unlimited height of it up 
at one time without it starting to fall one way or another, i.e. slump. In 
the past shuttering has been used for cob, like you would for concrete, to 
get tall thin walls  http://www.chook.demon.co.uk/cob/page4.gif might help 
if this still isn't clear.

I'm still interested to hear of any data on climate for places where cob 
does work, and for places where people would like to try cob but fear it's 
either too hot, too cold, too wet or too dry. All this stuff about 
different climates being suitable or not never seems to have any numbers, 
then when we get to mixes for cob and plasters everyone wants exact 
proportions - why bother? Maybe it depends on climate ;-)

What's the current cost of fuel and conventional insulation in the US?  How 
much do you spend on insulation, on heating and on cooling? What are the 
efficiencies of the heating and cooling devices? How soon does the 
insulation pay for itself? Is there a compromise between optimum insulation 
for winter and summer?

What happens in the price of oil goes up, does insulation go up in price or 
are the retailers more honest than that?  It might seem odd but in the UK 
the prices of these things are set largely by taxes so it has little to do 
with real economies and more to do with government views on global warming, 
pollution, imports and exports.

Michael Saunby