Cob/Cordwood Masonry Hybrid

[Mike Carter]

Michael Says:

[snip]>
>Cob was most common in
>England where such weather extremes are FAR from common.

Some say that was all they had to build with and the houses are cold.  Some
say that the ONLY place suitable for cob is where there are diurnal
extremes, such as high deserts.  We were told by "experts" that we could not
build with cob in the South - too hot, too humid, your house will melt (from
the humidity).

If I were reading this list without any experience, I wouldn't know what to
think.  Cob is such a joy to work with that I would hate to see even 1
person not consider it because of something they read over the internet
about its supposed thermal properties.  The same could be said of other
natural building technologies.

You will find cob houses in many different parts of the world and many
different climatic conditions.  Ask some people who live in them how they
like them and how they feel in the winter and the summer, what their energy
costs are like.   Do the same with cordwood or any other technology you are
considering.  Look carefully at the weather records for where you are
building and pay attention to the average temperatures.  Most people think
in terms of highs and lows, which are not very relevant to thermal mass
buildings.
>
Dave says:
[snip]
>>Also, the sustained 90+ degree F
>> temperatures with the high 90+ percentage humidity of late August would
>> eventually raise the internal home temperatures to the uncomfortable
stage.
>> You would end up having a building with its weak points in March and
>> September. The cold would be catching up with it in March and the warmth
in
>> late August (at least in N. Illinois).  >>
>
>Really good analysis of Cobs weakness in such extreme weathers.

Yes, I'd want some straw minibales (or other extra "outsulation") on the
outside of a hybrid cob/straw house in Illinois.  Summer should be no
problem, as average temps are 76 degrees F max for Illinois.
>
OK, now this is what I have direct experience with here in Texas.  Some nice
extreme hot weather.
1)  You will find humidity varies during the day.  In the summer here, it
starts at around 90-100% in the AM and often drops to 30-40% in PM.  The
clay in the cob has a proven ability to buffer humidity, which will make
your home feel cooler.
2)  Get some stats on the average temperature during a 24 hour period.  In
Austin, we had the hottest June on record, with 95 degrees or more for a
high much of the time and 108 one day (we cobbed that day).  The average
temp. for the month was 86 degrees.
This is because the high was only reached for a few hours during the day.
The thermal mass will tend towards that average temp.

There are many design factors which will make a house more livable.
(Ceiling fans, good window placement and ventilation, large South and West
eaves, trees, a living wall, ventilation at the top of a peaked roof, good
window quality and seals, etc.)

All kinds of stick-framers visited our place this summer and commented on
how cool it felt in the afternoon without even any doors or windows.

Mike Carter
cobcrew at sprynet.com
http://home.sprynet.com/sprynet/cobcrew
Austin, TX    USA