Cob and basements

[Keftydia at aol.com]

In a message dated 11/7/98 7:04:50 AM Eastern Standard Time,
s.zeidel at utoronto.ca writes:

<<  I was wondering if cob would be viable out east as well (I was thinking
about
 Montreal and Toronto). If not cob, then just what sorts of cheap
 altenative housing would be viable? >>

It seems that the viability of cob in different climates is a big source of
debate on the list.  While many point out that cob was used extensively in
Great Britain and parts of France (typically moderate, moist areas with
occasionally cold winters), others point out cob's thermal property of
averaging out daytime and nighttime temperatures, suggesting in areas that get
really cold for extended periods it may not be the best idea.  What I gather
from both responses is that yes, you can build a cob home in your area, but it
may not be as comfortable as other methods in colder climates.

I think you'll find many proponents of straw bale construction in your area.
>From what I've read on this list, straw bale offers much better insulation
(equal to or better than typical housing) and is perceived as more comfortable
in wintery climates.

I suggest that you look at the average temperatures in your region for the
year, for July, and for January to determine a method of housing that may be
suitable.  Monolithic structures like cob and rammed earth will tend toward
those temperatures over time (which could result in unpleasantly cold walls in
harsh winters) whereas structures with more insulative abilities (like
strawbale) don't really have this problem.

<<Also I was wondering if all the cob homes were above ground structures? I
didn't see anything resembling a basement among the pictures>>

Cob requires a foundation to bring it about 24 inches (61 cm) above grade
(guys...please correct me if I'm wrong) to prevent moisture wicking up from
the ground and causing structural decay.  The consensus is that cob walls need
to breathe, so I would limit it to above ground use.  I don't really see why
you couldn't have a basement, though, but I think you'd have to construct it
in the "normal" manner, adapt the foundation slightly for cob, then add the
cob walls.  This precludes having a cob floor (too heavy), meaning you'd incur
extra construction costs in building a subfloor over the basement, but if
you're going through the trouble of a basement anyway, that might not be a
major deterent.

<<Would a rooftop garden be possible (one that covered the entire roof)>>

I think we've tossed this question around before (or was that sod roofs?).
Maybe someone else can help on this topic?

Metta to all,

Ron Cameron