[Cob] Re: Foundations

[Barbara Roemer]

Peter wrote:
> 
> I'm under the impression that there are buildings in use today that have
> been standing for hundreds of years on foundations built without the use of
> cement.
Snip, snip.

I'm sure Peter is right, but local conditions obtain, and context matters.
As usual, I wonder about seismic zones, since I live in zone 3 of 5 (No.
CA.). We renovated a Victorian cottage, built about 1865, which had brick
and concrete perimeter foundations in places, and piers under the body of
the house, sometimes nothing more than a sizable rock with a post on it.
While the house hadn't slid off any of the rocks or piers, some had sunk or
moved somewhat so there was a lot of work to be done under it, and we have
never had the 100 year temblor that will eventually come with our proximity
to faults.  Every contractor and architect who looked at it, save one, told
us to replace the foundation with a perimeter concrete foundation, and to
replace the piers with good pads.  We chose a bit of new perimeter, some
pads, and a lot of jacking and reinforcing/sistering of beams and posts.  We
also put in a good deal of steel (bolting the plates to the foundation -
very little of that had ever been done) & sheer so the whole thing will move
as a unit in the event of a quake.  It's still there, but the timeline is
way too short to know if that will be sufficient: the building dept thought
so....   And when we build a hybrid bale/straw clay/cob house in this zone,
we will use RT with a concrete bond beam as the strongest foundation with
the least concrete.

Barbara