[Cob] cob/bales

[Kindra Welch]

Hi Robert - here in NM Sangre de Cristo Mountains...we have a frost line of
42" (to give you an idea of winters).  In building we opted for adobe/cob
walls all the way around with a bond beam on top.  Then roof and second
story resting on this bond beam and earthen walls.  Finally when roof was
*just about* done we tied strawbales to the exterior of north, west and east
sides to make 30" thick walls.  I say "just about" because in one section a
piece of tar paper wasn't quite secured, flipped back and allow one, just
one, rain storm to leak through the roof on the bales.  Within a week we
found mushrooms and had to pull bales out.  So, I would highly reccommend
not putting bales in until you have a very secure roof. Bales are not so
recoverable as cob.

Another issue for us is the gap between the earthen walls and bales.  No
matter how hard you push those bales against the dry cob its not a tight
fit, a perfect little network of passages for mice etc.  The cat has had his
work-fun cut out for him this summer.  We have ended up pouring small pumice
rock down this crevice to close it off.  It would have been easier to take
this step as we stacked bales up.

For all this work the house stays a very nice temperature
spring/summer/fall, though we haven't gone a winter in it yet.

Kindra


At 11:05 AM +0200 7/21/08, Robert Alcock wrote:

>We are looking at using a load-bearing hybrid straw-bale/cob wall
>consisting of straw bales laid on edge (35cm thick) with cob either side
>(10cm interior and 5cm exterior). We plan to pour a concrete bond beam
>at first floor and roof level of this two storey, 100m2 per floor, house
>and study centre.
>
>Does anyone on the group have experience with this "sandwich" type of
>wall construction?

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