Cob: Jelly Roll Design

[RobertCCardwell at aol.com]

Jelly Roll Design 

By Robert Cardwell, 1/26/02

I have a property in rural Indiana, in a nature preserve area, about 100 
yards from a lake on a hill with many trees.

I have been pondering the idea of building an alternative structure there for 
a few years. I have read about adobe, earth bags, rammed earth, earth ships, 
etc.   I have been very excited by these alternative designs.  However, I had 
two problems with most of them. The first is costs and the second is 
manpower.   I am one poor man.  Most of the projects have some expense or can 
only be accomplished by a group or community action. So the principles of 
cost and manpower have guided my design thoughts.

I have come up with a design idea, which is very eclectic and borrows from 
many of the alternative building ideas.  I wanted to get the economy from 
some designs, environmental empathy from others, strength from some, and ease 
of construction from others.   Finally, I wanted a design which allows 
artistic expression and has the possibility of being very life enriching.

I have come up with the idea of a jellyroll design.  The seed of this idea 
came from a recommendation to mix cob on a sheet and then to use the sheet to 
manipulate the cob.  I came up with the idea of why not just use the sheet in 
the construction. Sheets of plastic, burlap, hemp, cloth, woven fiberglass, 
are relatively inexpensive.  Why not just mix up the substance, tamp and 
compress, roll this up in the plastic, tie off, and viola…you have an earth 
or artificial log.  The size of the log could be determined by the size of 
the workforce.  The log could be laid like earth bags to build the wall.


I have done a lot of thinking on this design.   It has the benefits of earth 
bags and the ease of cob.  He jelly of the log could be very diverse as the 
sheet depending upon the location and application of the log in the 
structure.  For example, the foundation, or base structures of the wall could 
be built with a plastic sheet and a concrete, earth, or earthcrete "jelly".  

As the wall was built up, the material could change.  For example, the upper 
course could be of a more breathable sheet and lighter jelly.  Perhaps, even 
a papercrete jelly could be used with plastic and earth jelly with a burlap 
[or hemp] sheet.

Another key design idea could be what the center of the jellyroll was made 
of.  This center of course would be long and could be made of steel, plastic, 
or wood as need.  For example, a lintel may be made of a fiberglass sheet, a 
concrete jelly, and a rebar "rolling pin".  An upper course, or ring of a 
dome roof could be made by a sheet of 6 mil plastic, with a 1 inch PVC pipe 
rolling pin, and a jelly of papercrete.    PVC tube rolling pins could also 
be used in mid wall courses to serve as conduits for plumbing and electrical 
wires.

Most of my design ideas have been centered around building a beehive or domed 
structure.   The jellyroll logs would be laid in rings of decreasing sizes 
until the dome is formed.

Some of my other ideas are to do experiments with the wrapping sheets and 
filler substance. Some possible filling substances: waste paper, wood chips, 
gravel, sand, sawdust, etc.  A chipper could be used to re-cycle a variety of 
substances.

Another idea would be to experiment with the need for mortar.  The mortar 
between the log courses could be as simple as the use of barbwire as in earth 
bag construction.  The mortar could be cob or some other experimental 
substance.

The covering of the external structure could be with adobe, stucco, or earth 
plaster. The interior, windows, doors, and furnishing could be made by using 
"conventional" alternative building designs.

Finally, I have toyed with the idea of using a design of tension cables, 
suspension, and chain link fence to build an earthen yurt.

These ideas are perhaps the meandering thoughts of a loon, but I would 
appreciate any considered feedback.  

Thank you for your time in reading this.

Bob Cardwell   
 robertccardwell at aol.com