Cob Yoda's cob house

[Will Firstbrook WCB of BC]

Hi Mike,

Thanks for your reply lots of food for thought!

>-----Original Message-----
>From:	cobcrew at sprynet.com [SMTP:cobcrew at sprynet.com]
>Sent:	Wednesday, December 03, 1997 4:30 PM
>To:	coblist at deatech.com
>Subject:	Re: Cob Yoda's cob house
>[Will Firstbrook  WCB of BC]  snip 
> 
>[SNIP]Any Ideas on how this could be done?
>Cob roofing is our favorite topic.  We are planning both a 11' hallway with a
>cob 
>barrel vault and a 15.5' cob dome.  For our larger dome, we are thinking of
>using 
>cut Hebel aerated concrete block (very light weight, good insulator, about
>3-4x 
>stronger than the best cob mix we have made.) 
>[Will Firstbrook  WCB of BC]  
>I have never heard of this stuff, is it widely available and how much does it
>cost? Would you use it as tiles?
>
>  Note: we have not found any round windows that are screened and open.
>Anyone have any ideas
>about round windows where you need ventilation and have lots of mosquitoes?
>
>[Will Firstbrook  WCB of BC]  Initially I was thinking of imbedding the glass
>into the cob wall. Cheap and easy, but ventilation and fire escape now has me
>thinking... One possibility could be to use plywood to frame the window glass
>sandwich style,  and attach the window with hinges to a plywood not sure of
>the right word (frame/sill) that is embedded into the cob wall. A Jigsaw can
>shape your desired shape. 
>
>>Three possible techniques come to mind:
>>[SNIP]
>>3. Maybe the wattle and daub technique of getting lots of sticks tied
>>together in the shape of the structure then using them as a form to
>>massage the cob into.
>This is the one we're going to do.  We have a ton of bamboo cut and ready for
>use.  Might not be available in BC.  Hope to use a mesh system, with large
>pieces 
>interspersed with smaller ones.  About 4" square, tied with "black wire".  
>Thinking about 6-8" total thickness.  Shape is key - catenary or egg shaped
>helps 
>distribute lateral forces and will help with the snow load.
>>[SNIP]
>>Yet cob does not make a good roofing material even with a lime finishing 
>plaster.
>Well, what is the difference between all those cob ovens and a small dome?
>There are many adobe brick domes world-wide; cob offers some advantages over
>adobe brick, I think, in terms of the extra straw component adding to the 
>tensile strength and fewer cold joints.  Carol Crews (sp?) in New Mexico has
>a 
>hybrid cob/adobe structure with an adobe dome roof (not catenary).  She has 
>suggested a special sealant (silica-based) that waterproofs but still allows 
>water vapor to enter/exit the material.  
>[Will Firstbrook  WCB of BC]  
>I would like to know more about this "Gore-Tex" like sealant. But this part
>of the world is a lot wetter than New Mexico. So I do want a very water proof
>roof over the cob.
>
>
>If we run into difficulty, we have
>considered covering the cob with:
>1)  A silo top ($1,500 new from Minnesota).
>2)  Ceramic tile or synthetic tile or tiles made from recycled tires.
>
>[Will Firstbrook  WCB of BC]  Very interesting idea about car tires as
>roofing tiles.
>
>3)  A tin roof (best option for rainwater collection)
>
>[Will Firstbrook  WCB of BC]  
>I am thinking of using roof water for drinking and washing from the main
>structure so this seems to be a good option for that part of the roof.  
>4)  Some form of thatching.
>
>[Will Firstbrook  WCB of BC]  Seems too expensive at this time. I do want a
>creative house but one of our goals is to avoid or minimize any
>mortgage/debt. My goal is to simplify life and start doing things that are
>important to me rather than to work for a large organization to pay most of
>my income to mortgage interests and taxes.
>  >
>Best of luck with your project.  We have been getting some of our design
>ideas from an adobe book, "Adobe and Rammed Earth Buildings" by Paul McHenry,
>Jr.  There are several pages on adobe domes and barrel vaults.  And hey, if
>we have to make some bricks, we'll do it!
>
>Our details are at http://home.sprynet.com/sprynet/cobcrew
>Mike.
>
>[Will Firstbrook  WCB of BC]  
>
>Regards,
>Will