Cob: House plans/living roof

[jen walker]

Hi there Chuck, I know that a Quebec eco-architecture group called Archibio
have a booklet on how to do a living roof properly. They have studied and
tested this kind of roof for many years, perhaps 15 or more so are quite
experienced. They are architects and one of their group Michel Bergeron is a
co-author of the book 'Serious Strawbale' for strawbale in cold climates.
You can also write to them directly via their web site which is archibio dot
something.

This brings me to the topic of metal roofs and water-catchment. Something I
read in 'Serious Strawbale', that if you have a metal roof and lots of snow,
the snow slides off the roof which is a good thing but often ends up taking
the eavestroughs with it. Makes the case for a living roof more appealing.
The one thing I have against them is that they are rather low pitched which
is fine on say a small shed roof but for bigger places its nice to have a
peaked main roof because houses like that tend to look cosier and feel more
like home to us humans (something about our first dwellings being just
roofs). I'm getting this from "A Pattern Language' which is highly
recommended for anyone designing a home. Its expensive to buy but I got it
at the library. Its absolutely fascinating. A small house though wouldn't
need a steep pitch as much I imagine.

Jenny Walker



>From: "Waiting4 TheDay" <waiting4theday at hotmail.com>
>To: coblist at deatech.com
>Subject: Cob: House plans/living roof
>Date: Sun, Mar 30, 2003, 11:52 AM
>

> Hello,
>
> Been lurking on the list for quite awhile, but have yet to see my particular
> problem(s) addressed.  I am building a 20' inside diameter round cob house
> with a clerestory living roof system.  The circle will be split by a cob
> wall running east/west the the diameter of the house.  The base of this wall
> will be 24", while the base of the curved outside walls will be 18".  All
> walls will be load-bearing.  I've cut 12" diameter timbers to span the
> (maximum) 10' length from the inside wall to the outside.  Now for the
> issues...
>
> 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.  Stakes can be driven through them
> to secure them to the gravel in the trench, and flashing can be used to
> secure them to each other.  As an outside covering, I envision using a thin
> coat of concrete/fiberglass slurry sold in a bucket.  (I don't want to use
> this or the aluminum flashing or the pond liner for the roof, but can see no
> long-term, working alternatives.)  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).
>
> Next issue is the living roof.  Evans does deal with it some, as does Rob
> Roy.  The problem I'm having tho' is with the design of the fascia and how
> the water drains.  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. 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?  (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 it for now, but as things continue/evolve, I'm sure I'll post more
> questions.  Thanks for any insight.
>
> Chuck
>
>
>
>
>
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