Cob Re: you cob dome to be used for a sweat

[Vernon B. Johnston]

-----Original Message-----
From: patrick newberry <goshawk at gnat.net>
To: vajohnston at nas.com <vajohnston at nas.com>
Date: Wednesday, October 01, 1997 1:47 PM
Subject: you cob dome to be used for a sweat



>I saw you post on my guest book and was interested in you sweat
>is it straight cob?
>covered?
>other details ?
>Thanks

A while back, Pat asked me for some details on a cob sweat that I am
building.  I felt it also may be of interest to other cobbers so I am
responding to Pat and the Cob Site.

    I am currently building three cob structures on my property.  A home, a
cistern for rain water harvesting, and a cob sweat.  I have finished the
foundation for the home and was hoping to start cobbing.  But...with the
colder weather starting to set in, I decided to postpone the house cobbing
until next spring.  In the meantime, I will gather more building materials,
and prepare the floors for applying the cob/adobe floors.  That is for the
house aspect.
    Smaller cob projects seemed within my range for this year, so I built a
foundation for a cistern and for a sweat.  I hope to have both of them
completed by the end of November.  If there is interest, I will send more
info on the cistern at a later date.
    The cob sweat, which I prefer to call a Cob Swauna in honor of the
Native American Sweat and the European Sauna, is 9 and 1/2 feet inside
diameter.   I dug a one foot (+ or -) trench and filled it with drain rock.
I then mortared in a 6 to 10 inch rock wall.  Considering the location and
size of the Swauna I did not feel that the rock foundation needed to be as
high as my house foundation.  I also wanted to go lower to have less rock to
cover on the inside of the swauna.  The purpose of covering the rock with
cob is to insulate them from the heat generated during a sweat.  Those rocks
would get very hot and would hurt if you leaned your back against them.  As
it is, I designed the periphery with high rock on the outside, low on the
inside.  Therefore, I had very minimal covering to do.
     After the short wall was up I filled my circle with about 2 inches or
so with drain rock (just enough to bring it above the ground level).  I
leveled the floor the best I could, then added an inch and a half of wetter
than usual cob for the floor.  I left a gap of an inch or so between the
floor and the wall.  My thinking is to provide drainage for the steam that
will roll down the walls during sweat ceremonies.
    Before I started cobbing, I put in place 2 entry ways.  I suppose one
could cob the entry ways in, but I chose to use the downed trees from my
property to frame in the entries.  Some people may have only 1 entry, but I
prefer 2, with one being smaller than the main entrance.  My main entrance
faces south as per a dream that a Crow Native American Indian had about my
positioning of my sweat.  I felt honored to follow his dream for me.
    Now I am cobbing in the walls.  I am up about two feet.  I am using the
corbelling method described in the "Cobber's Companion" and which I learned
at a workshop about two years ago.   So far, I am discovering that I need a
cob mixture richer in clay, because I am adding more straw.   I add more
straw not only for the corbelling requirement, but for the "knitting"
together effect.  I do not want this cob dome falling down.
    Speaking of falling down.  I need to talk about protection from rain.
The last thing I need is for the roof to fall in.  Presently, I have a
"temporary" shelter built over the Swauna.  4 poles, some stringers and a
blue tarp keep the rain off and allow me to build.   Do I want to keep this
"temporary" roof up or do something different?  I have thought about a
clay/flour/sand  plaster mix for a roof, but question it's durability in the
rainy Pacific Northwest.  What I think may work is torch down roofing
material.  I talked to a roofer who said that it would be no problem to
apply.  Maybe, maybe not!   I need to, and plan on experimenting with both
of these mediums.
    Anyway, that is my Cob Swauna to date.  Any questions or helpful hints
or feedback is welcome.    Need to go now and put on another 6 inches of cob
before I go to work.   Vernon   vajohnston at nas.com