Cob Re: Beers cause cordwood dreams

[M J Epko]

	I got interested in cordwood a few years ago in my search for how to build
myself a house. In the last year or two, I've thought about and had
conversations with a couple people about substituting cob for cement in
cordwood construction; one of those people was Rob Roy. Meanwhile, there
are people who have given it a go. Rob had knowledge of one contemporary
place in Wales, but knew no specific details, that was built as a
cob-cordwood matrix, and he heard it was fine.

	The biggest concern, when substituting cob for cement in a typical
insulated loadbearing cordwood system (cob/insulation/cob from exterior to
interior), seems to be that the cob (which would only be three or four
inches wide and tall) might not be up to the necessary compressive
requirements (depending on the ratio of clay/sand/straw), particularly on
the exterior where it's more susceptible to saturation, and particularly if
it gets saturated at the bottom (due to melting snow, rain splash, etc). It
might ooze out like peanut butter, and that would cause some headaches.
Alternately, it could simply crumble. Rob suggests that using the
cob-cordwood matrix as infill for a post-and-beam frame might be
appropriate. I concur.

	If the insulation is omitted, that is using full-width cob, I don't have
any real worries, even in loadbearing applications. Rob seemed to think
that would be OK too. It would be a cold structure in cold climates though,
and if somebody backed into it with a pickup, it wouldn't do too well.
Michael's concern about the lack of bonding was on the money. That also
brings concerns about wind loading, roof uplift, and stuff like that into
play too.

	With typical cement-mortared cordwood walls, it's said that the wood could
rot fully away and the wall would still stand. I believe it. It would be
like a wine rack house.   :)   I favor houses that melt back into the
landscape at the end of their useful life, though, so do like the
cob-cordwood matrix idea.



   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   Freewheeling autonomous speculation - Think!
      Personality #7 represents only itself.
    M J Epko - duckchow at mail2.greenbuilder.com
               Kingston, New Mexico
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       Each morning sees some task begin,
       Each evening sees it close;
       Something attempted, something done,
       Has earned a night's repose.
              - Henry Wadsworth Longfellow,
                   "The Village Blacksmith"