Cob: Re: Insulation etc

[Mike Holland]

Sojourner wrote:

>Would the wood embedded in the walls have to be PT?  Or would normal
<untreated wood be ok, since the walls will not actually be wet (better
>not be!)  This would act like vertical "lathe", like they used to use
>for plastering.

Just for reference, one of the internal walls we removed was built with
vertical posts about 2 foot apart, with split oak laths nailed to them - the
kitchen ceiling/attic floor the same: the laths and posts had been there for
anything up to a century and showed no particular signs of rot or insect
attack.  I strongly doubt that they were treated in any way.  The lime in
the cob mix used round here tends to dissuade insects, anyway.

>Would you have to take special steps to make certain that the cob mix
>would hold with the weight of the "lathe" and the siding?

Then again, if you were going to go down this route, you might as well put
up a wooden framework against the cob wall once dry, and nail your
plasterboard/plywood/whatever to it - avoid the issue of the wall to lath
cohesion.  We're actually using a steel framework in the bathroom area, if
only because it's quick.  I don't enormously like the very smooth surface
this type of system gives you - it's somewhat at odds with the "not a
straight line nor right angle in sight" aspect of the rest of the house, but
you have to balance aesthetics with convenience sometimes - and in any case,
we can always lob some of the hemp/lime render on it later to soften the
edges, if we feel like it...

Mike