Cob Re: Work in Georgia last weekend

[Patrick Newberry]

 My understanding is the completed top
> section of the dome would consist of the following materials in order
> from top to bottom:
> 
> cement

add another layer of carpet here. 

> tar paper
> straw clay (liechtlehmbau)
> cement
> carpet
> oak saplings
> lime earth plaster
> 
> Your method & materials sounds quite reasonable. I wonder if
> condensation is a potential problem due to the widely differing rates of
> breathability of your materials. Like the adobe buildings that were
> plastered with cement that created a vapor barrier that caused the adobe
> walls to deteriorate. I have no idea if this is a problem in this case,
> that is why I'm asking. If there is a potential problem do you have any
> ideas to deal with the problem? I wonder if there is a cheap Gore-Tex
> type cement that allows vapor to pass but not water. Perhaps air vents
> in the cement that go upward from outside to inside so no rain can enter
> but allow trapped moisture to escape.

All good questions and one reason I am building the proto-type around 
the well pump prior to building the big dome. I still think it will 
work because the cement carpet walls do have some breathability. If I 
watter proof anything it will be the outer layer of carpet. The inner 
layer will not be waterproofed.  I am  expecting the slope of this 
thing to beable to carry most of the water off, but even so 
I will have some vents in this because it's a high ceiling 
and will trap a lot of hot air so I need to have some type of 
venting in the ceiling. Remember this is really only the "roof" 
section of the dome and not the whole dome. The water running off the 
"roof" section of the dome will hit another roof from an outer wall 
and run off past an over hang. There is no such thing as cheap 
Gore-tex as far as I know. 


>  
> I am also interested in a much smaller scaled dome so I am very
> interested in your ideas and experiences. 
 

When I get the proto type done, I'll take photos and post them on the 
web. I have a small foundation about halfway done for this 
proto-type.


Pat