Cob: Cob-Strawbale Hybrid.

[Tony Glaser]

Hi Tom,

I'm not sure which of my responses were on list or offlist, so I'll just
sum up the responses:

   Insulation is important in the winter for keeping the heat in, and the
summer for keeping it out. No one on this list seems to know of any
attemps to use cob in our cold, northern, central climate.  All northern
cob structures seem to be near large bodies of water which prevent
temperature extremes during the seasons much as cob does during the day.


You and Rebecca Kirk <beckykirk at worldnet.att.net> have both expressed
enthusiasm for a cob-strawbale hybrid. She wrote:

>My understanding is that the thermal mass of cob creates a situation
>where the interior of the building tends towards the AVERAGE daily
>temperature outdoors.  This can be offset somewhat in the winter by
>passive solar energy... but in general if your average daily temp. in the
>winter is say 0 degrees.... that's what your interior is going to tend
>toward.  I live in Michigan and intend to do a hybrid cob and strawbale
>house so I can get the beauty and sculptural qualities of cob as well as
>the thermal mass... and the insulative value of straw.

You wrote:

> It will be important to have a good, high foundation with a damp barrier, 
> and significant overhangs.  This is to protect especially the bottom portion 
> of the wall from splashback, and keep it dry.  It will go a long ways to 
> prevent flaking and cracking due to moisture in the cob freezing.

Good advice, I'll jot it in the book I'm using to plan.

> 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.

Anyways, sorry for that sidetrack.

It seems that You, Rebecca, and I are cob-strawbale pioneers.  You
probably both know more about both than I do, but I'm a quick study. For
reference, here is our emails:

Rebecca Kirk  beckykirk at worldnet.att.net
Tom Fetter    tom_fetter at hotmail.com
Tony Glaser   aglaser at engsoc.carleton.ca


I visited a sustainable-living center in Ontario last July. They had a
very small round cob hut in the works. I think they were hoping to have it
finished by the winter and I'll ask them what the insulation is like.
They also have some strawbale structures, so I'll ask what they think
about the concept of a hybrid.

I'm also aware that there are some cob houses and a cob church in southern
Ontario.  I don't know if any of them get the extremes I get, but I'd like
to somehow get a hold of the owners and ask them about their winter
experiences.  Does anyone have a clue how to get a hold of the owners?

Tony


--------------------------------------------
Anthony Glaser
aglaser at engsoc.carleton.ca
http://www.engsoc.carleton.ca/~aglaser
Year 2 Electrical
Faculty of Engineering, Carleton University