Cob: RE: RE: Posts embedded in cob

[jamie.ayres at m2.com]

Hiya,

I just want to clarify this for myself...

What you are saying is that cob walls needs no damp proof course as long 
as the base of the walls are made of some form of cement/stone. This 
should be high enough to prevent the splashback from ground level reaching 
the cob level. The base should not be completely even and smooth on top 
but should be rough and uneven to allow the cob to bind well with it. 
Should the internal floor also be up to the level of the cob? Being in the 
UK means that the house will have to withstand pretty continuous rain at 
some times so how high would anyone sugest the floro should be to avoid 
dampness creeping in?

The earthern floor can have some kind of damp course and perhaps an 
insulation layer as well? Has anyone added underfloor heating to a cob 
house?

Am I also correct in saying that the walls, in theory at least, need no 
additional insulation and that they are strong enough to support a two 
story building and roof with no further timber framing (given that the 
size of the rooms will be sensible... less than 12 feet across).

Is this correct :o)

Sorry for all the questions!

Jay






"Firstbrook, Will" <wfirstb1 at wcb.bc.ca>
Sent by: owner-coblist at deatech.com
11/02/00 09:01 PM
Please respond to "Firstbrook, Will"

 
        To:     "'Shawn Honeychurch'" <ironfire at cyberlink.bc.ca>, coblist at deatech.com
        cc: 
        Subject:        Cob: RE: RE: Posts embedded in cob

Regarding your design, my understanding is the cob should start approx. 2' 
above ground at least on the exterior so no water can be wicked up into 
the cob. Also the foundation that cob sits on should ideally be rough so 
the the cob is keyed into the foundation and somewhat breathable. Stone & 
cement foundations work well. You can when making the foundation insert 
large galvanized nails into the corners (embedded in cement) wherever you 
want to place the posts. Then drill a hole into the bottom of the posts so 
it is well fastened to its location. 
 
I'm not sure of using the plastic under the cob, tar paper maybe. 
Personally I wouldn't use it. I have never seen it used. Perhaps under the 
foundation over the floor area. When I built my earthen floor I put 6 mil 
vapor barrier down then 5" of 1" river rock, straw, then placed the 
earthen floor on top of that.
 
Regards,
Will