Cob: New to this list and the idea of cob

[Darel Henman]

IBX Eri,

> >>>>>>>>They Styrofoam, would not need to be in the center and would be better
> place near the outside, except for the South facing portions of cob
> wall.<<<<<<<<<
> 
> I think you are correct. If insulation is to be added to cob wouldn't it be
> better to have it outside the mass of the cob walls? It seems to me this would
> keep the wall strong.
> I do have a question though. My understanding is that cob needs to breathe and
> that insulation and a vapor barrier would inhibit this and may lead to possible
> moisture problems?
> Would appreciate someone more qualified sharing their views on this. 

Cob walls can breath and its good.  It's not necessary I dare say.  But,
the point in using earth is that it does breath and helps regulate
humidity inside the house. 

If you used an outside vapor barrier the wall could still breath from
the inside.

Also, you don't need a water vapor on the outside if you use the ideas
that Charmaine said about using bagged ash bags and then putting a
lime-mud over it, or my idea about using a light clay (straw or wood
chip) mix and then use a lime-mud plaster over it.

I suppose you could even put straw-bales around the cob wall and then
paint over it.  Sounds like overkill, but its possible.   Not everything
has to be done at once.   

Owner-builders can, add to insulation to wall when they want or need to
and don't have to finish the whole thing in one year.  A good cob wall
might not even need the extra insulation, but you have to consider your
local climate and solar radiation patterns, etc..  See if you can get
data from some people who already have cob houses, about performance for
their area.

Darel