Cob: new to list, and cob

[Shannon C. Dealy]

On Thu, 16 Dec 1999, Ted Schluenderfritz wrote:

[snip]
> I come from MN and am use to cold weather --average low temp in January -1.4,
> in North East PA it's 18.4. What exactly would the 8r be like...would it just
> cost more to heat or would it feel very cold. Does anyone have a cob house in
> this type of climate? 

I can't speak from personal experience in your type of climate, but with
temperatures in that range, you will probably want to insulate the outside
of the building, cob is a lousy insulator.  What cob does best is
stabilize your building temperature.  In a mild climate with good solar
design, it is possible to store enough heat in the walls during the day in
winter to keep the building reasonably warm at night with minimal
additional heating.  Thicker cob will make the temperature stable over a
longer period of time, but ultimately, in an area where the temperature
gets cold and stays cold for weeks at a time, particularly if it is
cloudy, the cob will not get enough sun to keep it warm, so you will end
up having to supply heat to make up for the loss through the cob, which
will be substantial if it is uninsulated.

> I was thinking that if I made walls which started at 4 feet wide, and then
> quickly tapered to 2 foot it would help with keeping the house warm (like a
> buttress [if that is the word I'm looking for])

This will stabilize the temperature over a longer period, but you will
still lose alot of heat in cold climates.

> how expensive and feasible is a thatched roof. Does anyone know of a master
> thatcher who returns your phone calls :^)

Last prices I heard for thatching put it at around 2 to 3 times the price
of conventional three tab asphalt shingle roofing, which given that it
lasts 2 to 3 times as long makes it just as cost effective, though the up
front price is rather high.  I only personally know two master thatchers,
one in Washington state, the other in Denmark, though I have briefly
corresponded with a third one who lives closer to your location, his
name is Colin McGhee and he has a web site at:

        http://www.thatching.com/

[snip]
> >From what I've been reading, straw bale is not as highly insulative as once
> thought and that it will rot in a short time. How often would one have to

I haven't followed recent discussions on it's insulative value, but last I
heard, both sides of the debate still gave it a very high R-value, giving
a range of R35 - R50 depending on who you believed

> rebuild walls made of strawbale. Plus it sounds awfully fussy with keeping the
> lower level dry(?)

As far as keeping the straw dry, it is important to remember that the
straw is inside of your wall, and if moisture is getting into your wall,
you've got serious problems even if you are using a conventional wall
made with wood framing and fiberglass insulation.  You can easily get mold
and rot in the wood framing, and though it may take a little longer than
a strawbale wall would, it can still cause serious damage.

> what about basements? does anyone recommend them, or not recommend them?
[snip]

Cob or strawbale?

I don't know of anyone who has tried strawbale in basement walls, but it
would depend on if you can devise a means of keeping moisture out of the
walls, and provide enough structural support to keep the weight of the
surrounding earth from collapsing the walls.  Cob will stand up to
the moisture better, but will still need protection from water, and
structural support to deal with the weight of the surrounding earth would
still be an issue.


Shannon C. Dealy      |               DeaTech Research Inc.
dealy at deatech.com     |          - Custom Software Development -
                      |    Embedded Systems, Real-time, Device Drivers
Phone: (800) 467-5820 | Networking, Scientific & Engineering Applications
   or: (541) 451-5177 |                  www.deatech.com