Cob: Re: House Plans/living roof

[Chuck & Linda]

Chuck wrote

I intend to use a rubble trench system for the foundation.  Rather than
build a stemwall of expensive material (block, rock, concrete), I have
access to a large number of incredibly sturdy plastic soda cases with solid
quarter-inch sides.  The idea is to fill these with gravel and use them as
blocks, thus providing a moisture break.

****This sounds like a good idea. I am not so sure that you would need to
connect the baskets to each other as the cob is so monolithic and heavy,
those baskets won't be going anywhere, plus you would be slathering them
with a fibre cement. I also doubt that you would need to drive those stakes
into the trench, gravity will take care of you.

  Here's the question:  I plan on having
12" of cob on the gravel in the soda case, while the other 6" will be
resting on the gravel that will underlay the cob floor.  Is this a problem?
I can't find any reference to this situation anyplace (and I've read Ianto
Evans' "Hand-Sculpted House" twice).

****I am not clear what you are trying to do here. It seems that you are
placing cob in the bottom of the baskets ontop of the rubble trench?
  Evans states that the waterproof layer goes over the
fascia, yet his diagram in the book doesn't show that.  And everyone says
that the waterproofing should be covered to avoid degradation from UV, but
if it runs over the fascia it will be exposed to the elements.
***** I have not built one yet, but I am in the process of doing so this
spring. I was planning on just attaching the membrane to the inside edge of
the fascia stopping short of the top lip. I may attach it with a battan.

 Besides the
obvious, my question is would a fascia even be necessary if the slope of the
roof were shallow enough to prevent erosion and you had plants aggressive
enough to hold the soil in place?

*****I would go with convential wisdom here. I wouldn't trust the
combination of gravity mixed with a gully washing rain, you
could loose alot of good soil and by the time you have done all that work,
every grain of soil will be important!

 (BTW, I'm a nurseryman, and there are two
genus that, in my mind, would work wonderfully on a living roof: the mints
and the bellflowers (specifically Campanula rapunculoides and C. punctata)).

***** That's what I would like to hear about, plants that could work in the
harsh shallow environments, say 4-6". Any other plants that you have thought
about? What about Northern Alpine Plants?

Its good to hear that another Chuck is out there!

Chuck Learned
Helping Hands in Wisconsin
Natural Building and Sustainable living
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