Cob foundation cement

[Mark A Hoberecht]

At 03:41 AM 2/26/98 -0800, you (Ian Marcuse - vtrac at alternatives.com) wrote:

>We are building a small cob meditation space in our backyard and are now in
>the process of building our stone foundation. We already have the rubble
>trench in and are now laying the large stones. Our wall is only about 12
>inches wide which makes it a little harder to dry stack.  We are
>considering using some type of mortar to jam into the stones but do not
>want to use cement. We are thinking that perhaps straight cob would work
>fine, but we are wondering what natural materials could be added to give
>the cob more strength, adhesion and waterproofing properties?  Has anyone
>drystacked a narrow wall (1 stone width in size)? How solid, safe is it?
>If anyone has any experience with this thanks

Ian,

The colonists found that an exterior lime mortar (outer one third) and an
interior clay mortar (inner two thirds) worked well in their stone walls.
Clay alone proved not to have enough weather resistance -- the lime on the
exterior solved the problem.  I used this principal in the construction of
my hybrid cob/strawbale building, using straight cob for the inner mortar
in my foundation wall.  It worked great!  Have yet to chink in lime mortar
on the outer surface, and may never do so.  My wide overhangs have
prevented any water penetration, and all those EXTERIOR nooks and crannies
make great habitat for all my mice and snake buddies.

Best ....  Mark Hoberecht