Cob: INSULATION FACTS, etc., etc., etc.

[DoNegard at aol.com]

Michael
<<  On 19 July 1999 22:29, John Schinnerer 
 [SMTP:John-Schinnerer at data-dimensions.com] wrote:
 [SNIP]
 > Focusing on the R-value of cob is to me silly, because cob is not 
 primarily
 > an insulative material, it is primarily a thermal mass material.  In
 > locations where thermal mass alone will not "work" for whatever reasons
 > (lack of sun for passive solar, not wanting to run a woodstove all 
 winter,
 > etc. etc.) cob alone will not work - and it may or may not be useful as 
 part
 > of a structure, depending on how and where it is used.
 
 That's not really true either.  It's fair to say that cob has high thermal 
 mass, but it is primarily a construction material used for the external 
 walls of buildings.  It has been used as such for centuries, ancient cob 
 buildings make little or no use of cob internally (it would be wasteful of 
 space, and possibly effort and maybe materials - though evidence is that 
 internal walls used more expensive/scarce materials).  There is no evidence 
 from any old books or decriptions I have seen of building techniques, 
 choices of materials, or living conditions prior to this century that 
 insulation, or thermal mass of buildings was ever an issue.
 
 Various folks have at times on this list suggested internal thermal mass 
 structures to hold heat in their house, either using cob for internal walls 
 or insulating the outside of a cob house.  Whilst there is no reason I can 
 see that this won't work, there's no precedent for it either.  To my mind 
 if you just want a large thermal mass inside your house it makes no sense 
 wasting space with the relatively low thermal mass of dry soil when you 
 could get a a few crushed motor vehicles and put them in your living room, 
 or use heavy cast iron heating equipment.>>

Thanks, Michael
It appears to me that the sources of information in some of these cob 
discussions sometimes covers quite a wide range of reliability, including 
mixtures of wishful/hopeful thinking, theoretical attempts to explain what 
dead people had on their minds, recorded history, eyewitness evidence, and 
actual experience.  

It also appears that sometimes this mixture occurs withing a single statement 
by a person.  This makes it require vigilance in sorting the wheat from the 
chaf.  Don't get me wrong - I am up to the task - but it would be easier if 
the authors were more careful of their mix.  When I get stuff mixed up, I 
want to know, so show no mercy, please.

Don in Hot Springs, SD