[Cob] cob greenhouse and Washington, DC

[raduazo at aol.com]

  Thanks to Shanon and everyone else that replied. I should clarify a 
few points about the details of construction. The "rubble" that we are 
planning to use is a manufactured product which we can obtain very 
cheaply here and there are three choices. The first is called crusher 
run from a blue stone plant ant consists of crushed bluestone exactly 
as it comes out of the crusher. It is a mixture of all different sizes 
stone from golf ball size to powder. Light tamping and wetting from a 
hose will compact the stone to a point where further settling is 
unlikely but it still permits relatively free drainage. The second 
material is called rock dust. That is the fines which are left over 
when crusher run is screened to produce the different grades of gravel. 
I use this material for setting stone walkways I also used it to make 
an earth floor. Small amounts of clay slip and shredded straw mixed 
into stone dust with a rototiller will produce a one or two layer floor 
which does not crack and is relatively dust free.
  The third material is nearly identical to rock dust only it is made 
 from broken up cement pavement from which the steel has been removed. 
It is the cheapest stuff you can get. It makes great cob or earth floor 
material, but there are not as many locations where it is available.
  The plane is to dig a trench, place drainage pipes and possibly a 
geofabric liner and fill it with the crusher run to the surface. We 
will then cut the tops off a series of tires placed on the crusher run 
and fill them with rock dust or crusher run. A second and perhaps a 
third course of tires will be cut to form an open top and placed 
directly on top of the first course. Note we are not staggering the 
courses into a running bond because we want strong support columns 
10-16 inches high supporting the bale/cob wall. By filling or partially 
filling the lower or middle tire I think we can thus adjust the height 
of the knee wall so that the bale wall can be constructed with out 
cutting bales.
  Chicken wire will be strung between the tire columns attached to the 
treads with drywall screws and washers and the space between the tire 
columns will be filled with fist sized rocks gathered from a neighbor's 
field, then the rocks, tires and chicken wire will be covered with a 
thin layer of cement or lime putty.
 We will provide a roof and construction can begin.
  Bales will be placed on the outside edge of the tire columns and 
buttered with cob mortar. Split bamboo will be stuck into the mortar 
and successive bales will be placed directly on top of the lower bales. 
Again we are not staggering the bales to avoid cutting. We believe the 
split bamboo will strengthen and stabilize the courses of bale better 
than using a running bond.
  Nylon ties will be attached to some of the split bamboo strips and 
will project to the inside of the wall. Cob will be made from rock dust 
and local clay using a rototiller and/or a back hoe. (We want to 
compare the relative speed and quality of the mixes).
  In the previous bale/cob hybrid wall the cob tended to slump away from 
the bale when we built too fast and too wet. To prevent that we will 
attach the nylon ties to dead-man anchors in the cob wall.
  I think it should work. All I need is for Chris to get his act 
together for phase one.
 Thanks again for the input and other helpful comments.
 Ed


 -----Original Message-----
 From: dealy at deatech.com
 To: raduazo at aol.com
 Cc: coblist at deatech.com
 Sent: Mon, 5 Mar 2007 19:16:28 -0800 (PST)
 Subject: Re: [Cob] cob greenhouse and Washington, DC

 On Sun, 4 Mar 2007 raduazo at aol.com wrote:

 [snip]
  > I picked up a copy of “The Tire House Book” by Ed Paschich and 
Paula
  > Hendricks and note that the Earthship structures are made with 
concrete
  > foundations. This seems crazy to me since cob and adobe structures 
are
  > often built on rubble trench foundations. This would negate our 
reason
 > for using tires.
 [snip]

  I don't believe this is how earthships are normally done, check 
Michaels
  Reynold's books, he is the architect who originally created the 
earthship
 / tire house concept. I would check, but my copy is about 8,000 miles
 away and my arms won't reach that far :-)

 Shannon C. Dealy | DeaTech Research Inc.
 dealy at deatech.com | - Custom Software Development -
 | Embedded Systems, Real-time, Device Drivers
  Phone: (800) 467-5820 | Networking, Scientific & Engineering 
Applications
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