Cob in really cold climates

[Shannon Dealy]

On Fri, 30 Aug 1996, FROG wrote:

[SNIP]
> An interesting idea.  You could also make this into a form of trombe 
> (spelling) wall.  Where the cob wall supports the roof, but another foot or 
> so in front would be a glass (or perhaps even a seasonally plastic sheeting) 
> wall that does a better job of trapping the heat.  There would be holes at 
> the base and top of the cob wall to let air circulate.
> 
As it happens, the picture on the cob web site titled "two story with 
unfinished exterior" is just such a design.  The building is not yet 
complete, so the glass front is not yet installed, but if you look 
closely you can see the holes at the base of the wall.

On a related note, most of the pictures are actually much sharper than
what you see on the web pages, I compressed them heavily in order to 
reduce download time to 10-20 seconds.  Would anyone like to see 
higher resolution versions of these pictures posted?

> One concern, however, would be that because that a single monolithic wall 
> would not be very stable because it had not corners supporting it (I hate to 
> have that baby fall on me!), but you could turn the corners on the wall for 
> 3 feet or so and perhaps solve that problem and still make the rest of the 
> house bale.  

A lot of the solar exposure you get even in winter falls on the West and
East sides of the building, so you probably would want even more than
3 feet beyond the corners to take advantage of it.  Using a south wall
shaped as a half circle would be even better.

Cob Cottage Company prefers curved walls because of the aesthetics, 
greater stability (regardless of construction medium), and if there should 
be an major earthquake, the walls will tend to fall outward.  I prefer 
round buildings in general for the simple reason that they are more 
efficient.  A single story 900 square foot house built using straight 
walls requires at least 120 linear feet of wall to build.  A round 
building would require only 106 linear feet for the same square footage, 
a 12% reduction in materials, labor, and most importantly thermal losses 
through the completed walls.  Obviously the reduction in materials & labor
will vary depending on the construction medium.

Shannon Dealy
dealy at deatech.com