Cob Construction
Cob is an ancient method of building
with earth and straw or other natural fibers easy to
find in the surrounding area. It is quite similar to
the adobe one sees abroad, in that the basic mix of
clay and sand is the same, but it usually has a higher
percentage of long straw fibers mixed in. Instead of
creating regular blocks to build with, cob is normally
applied by hand in large gobs (or cobs) which can be
easily handled during the construction process. The
mixing of the the clay/sand/straw is with the bare feet;
for this reason, it is fairly labour intensive.
Because of all the straw, cob can be
slightly more insulating than adobe, but it still would
not make a very comfortable house in a climate of extreme
temperatures. The wonderful thing about cob construction
is that it can be a wildly freeform, sculptural affair.
I've seen some very charming homes made this way. Cob
was most common in England in the nineteenth century,
and many of those buildings are still standing especially
around Devon where new Cob houses are still being built
by specialist cob experts.
A variant of cob is what is commonly
known as "light straw". This is made with
the same long fibers of straw which are thrown into
and worked through in a large vat. The idea is to coat
the straw with enough of clay to get them to stick together,
but not too much that it makes a gluey clump. Light
straw walls could be useful for interior partitions
and even exterior walls if it is thick enough. These
walls would be more insulating than regular cob having
a higher straw content, but they require a timber frame
of some sort because the straw itself would not be load
bearing. |